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  • Springer  (259,191)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • 2010-2014  (265,551)
  • 1995-1999
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  • 1935-1939
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  • 1995-1999
  • 1990-1994
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  • 1
    Publication Date: 2020-11-16
    Description: Active volcanoes characterized by open conduit conditions generate sonic and infrasonic signals, whose investigation provides useful information for both monitoring purposes and studying the dynamics of explosive processes. In this work, we discuss the automatic procedures implemented for a real-time application to the data acquired by a permanent network of five infrasound stations running at Mt. Etna volcano. The infrasound signals at Mt. Etna consist in amplitude transients, called infrasound events. The adopted procedure uses a multi-algorithm approach for event detection, counting, characterization and location. It is designed for an efficient and accurate processing of infrasound records provided by single-site and array stations. Moreover, the source mechanism of these events can be investigated off-line or in near real-time by using three different models: i) Strombolian bubble; ii) resonating conduit and iii) Helmholtz resonator. The infrasound waveforms allow us to choose the most suitable model, to get quantitative information about the source and to follow the time evolution of the source parameters.
    Description: Published
    Description: 1215–1231
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: JCR Journal
    Description: open
    Keywords: infrasound ; monitoring system ; Mt. Etna ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-06-25
    Description: A multi-model set of atmospheric simulations forced by historical sea surface temperature (SST) or SSTs plus Greenhouse gases and aerosol forcing agents for the period of 1950–1999 is studied to identify and understand which components of the Asian–Australian monsoon (A–AM) variability are forced and reproducible. The analysis focuses on the summertime monsoon circulations, comparing model results against the observations. The priority of different components of the A–AM circulations in terms of reproducibility is evaluated. Among the subsystems of the wide A–AM, the South Asian monsoon and the Australian monsoon circulations are better reproduced than the others, indicating they are forced and well modeled. The primary driving mechanism comes from the tropical Pacific. The western North Pacific monsoon circulation is also forced and well modeled except with a slightly lower reproducibility due to its delayed response to the eastern tropical Pacific forcing. The simultaneous driving comes from the western Pacific surrounding the maritime continent region. The Indian monsoon circulation has a moderate reproducibility, partly due to its weakened connection to June–July–August SSTs in the equatorial eastern Pacific in recent decades. Among the A–AM subsystems, the East Asian summer monsoon has the lowest reproducibility and is poorly modeled. This is mainly due to the failure of specifying historical SST in capturing the zonal land-sea thermal contrast change across the East Asia. The prescribed tropical Indian Ocean SST changes partly reproduce the meridional wind change over East Asia in several models. For all the A–AM subsystem circulation indices, generally the MME is always the best except for the Indian monsoon and East Asian monsoon circulation indices.
    Description: Published
    Description: 1051-1068
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: open
    Keywords: CLIVAR C20C ; Asian-Australian monsoon circulation ; AGCM ; Reproducibility ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2020-11-16
    Description: The presence of quarry and mine blasts in seismic catalogues is detected using the Wiemer and Baer (Bull Seism Soc Am 90(2):525–530, 2000) algorithm. The procedure is based on the observation that quarry blasts generally take place during daytime hours: the areas with a high ratio of daytime and night-time events are likely to be regions with quarry activity. In the first part of this work we have tested the method, using both a synthetic and a regional catalogue; in the second part the procedure has been applied to some of the European regional catalogues available on line. The comparison between the results obtained and the location of known quarries and mines for the analysed catalogues confirms the reliability of the methodology in identifying mining areas.
    Description: This research was partially supported by the transnational access activity of the European Union project NERIES (contract number 026130)
    Description: Published
    Description: 229–249
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: open
    Keywords: quarry blast; mine blast; seismic catalogue ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2020-10-26
    Description: One of the main objectives of the ITACA (ITalian ACcelerometric Archive) strong motion database, promoted by the Italian Department of Civil Protection, was to improve the characterization of the recording sites from a geological and geophysical point of view and to provide their seismic classification according to the seismic norms pertinent to Italy, namely the Eurocode 8 and the National Technical Norms for Constructions. A standard format to summarize the available information for the recording stations was first produced, in terms of a technical report dynamically linked to the database, i.e., some of the relevant information is automatically updated when the corresponding fields of the database are modified. Then, an important activity of collection, qualification and synthesis of available data was carried out, especially for stations that recorded the strongest earthquakes in Italy in the last 40 years, and for which a relevant number of studies have been published. In spite of this activity, among the more than 700 strong motion stations present in the ITACA database, only a limited number of them could be characterized by quantitative information on subsurface soil properties. For this reason, a dual seismic site classification criterion was implemented, either based on the standard Vs,30 scheme, or, in the absence of such information, based on an expert opinion supported by shallow geology maps, mostly at 1:100,000 scale, and when available on the H/V ratios calculated on recordings. Owing to the relevance in the Italian geographic and morphological context, a special care was also given to the topographic classification of stations, based on suitable criteria developed within a GIS environment.
    Description: Published
    Description: 1779-1796
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: ITACA database ; Strong motion station ; General characterization ; Site classification ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2020-11-16
    Description: Earthquake catalogues for Romania supply for 11th–15th century earthquakes located in the region of Vrancea records that consist of a complete set of parameters, including magnitude and depth. Scope of this paper is to verify the reliability and consistency of these parameters with the informative background as explicitly referenced by the catalogues. After retrieving the original sources they mention, the set of data appeared to be related almost exclusively to the Russian plain and too poor to be at the very origin of the parameter assessment. Data for 19th–20th century earthquakes, such as instrumental locations and CMT solutions, added to the understanding of the macroseismic response of the Russian plain to Vrancea earthquakes. On the one hand, the investigation and analysis of historical earthquake records for the fourteen events listed by the catalogues in the 11th–15th centuries has shown that for three earthquakes (1022, 1038, 1258) no primary sources could be traced, and three more earthquakes (1091, 1170 and 1328) are attested only by scarcely reliable records and had to be classified as doubtful, and one (1473) is simply a duplication of the 1471 event. On the other hand, the availability of data on recent earthquakes that may be compared to historical ones in terms of macroseismic effects allowed the authors to agree with the previous catalogue compilers’ solution with regard to both magnitude and depth of the past earthquakes for which do exist reliable primary historical records.
    Description: Published
    Description: 575–604
    Description: 4IT. Banche dati
    Description: JCR Journal
    Description: open
    Keywords: Vrancea earthquakes ; 11th-15th earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Springer
    In:  EPIC3Earth System Science: Bridging the Gaps between Disciplines Perspectives from a Multi-disciplinary Helmholtz Research School, SpringerBriefs in Earth System Science, Heidelberg, Springer, 138 p., pp. 42-45, ISBN: ISBN 978-3-642-32234
    Publication Date: 2019-08-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 7
    Publication Date: 2017-01-16
    Description: Early life stages of marine crustaceans respond sensitively to elevated seawater PCO2. However, the underlying physiological mechanisms have not been studied well. We therefore investigated the effects of elevated seawater PCO2 on oxygen consumption, dry weight, elemental composition, median developmental time (MDT) and mortality in zoea I larvae of the spider crab Hyas araneus (Svalbard 79°N/11°E; collection, May 2009; hatch, December 2009). At the time of moulting, oxygen consumption rate had reached a steady state level under control conditions. In contrast, elevated seawater PCO2 caused the metabolic rate to rise continuously leading to a maximum 1.5-fold increase beyond control level a few days before moulting into the second stage (zoea II), followed by a pronounced decrease. Dry weight of larvae reared under high CO2 conditions was lower than in control larvae at the beginning of the moult cycle, yet this difference had disappeared at the time of moulting. MDT of zoea I varied between 45 ± 1 days under control conditions and 42 ± 2 days under the highest seawater CO2 concentration. The present study indicates that larval development under elevated seawater PCO2 levels results in higher metabolic costs during premoulting events in zoea I. However, H. araneus zoea I larvae seem to be able to compensate for higher metabolic costs as larval MDT and survival was not affected by elevated PCO2 levels.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
    Publication Date: 2017-04-04
    Description: A new method of macroseismic surveys, based on voluntary collaboration through the Internet, has been running at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) since July 2007. The macroseismic questionnaire is addressed to a single non-specialist; reported effects are statistically analysed to extrapolate a probabilistic estimate of Mercalli Cancani Sieberg and European Macroseismic Scale intensities for that observer. Maps of macroseismic intensity are displayed online in almost real time and are continuously updated when new data are made available. For densely inhabited zones, we have received reports of felt effects for even very small events (M=2). Six earthquakes are presented here, showing the ability of the method to give fast and interesting results. The effects reported in questionnaires coming from three towns are carefully analysed and assigned intensities are compared with those derived from traditional macroseismic surveys, showing the reliability of our web-based method.
    Description: Published
    Description: 1.11. TTC - Osservazioni e monitoraggio macrosismico del territorio nazionale
    Description: JCR Journal
    Description: open
    Keywords: Earthquakes ; Macroseismic intensity ; Questionnaire ; Macroseismic effects ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-03
    Description: The development of the INGV (Istituto Nazionale di Geofisica e Vulcanologia)-CMCC (Centro Euro-Mediterraneo per i Cambiamenti Climatici) Seasonal Prediction System (SPS) is documented. In this SPS the ocean initial conditions estimation includes a Reduced Order Optimal Interpolation procedure for the assimilation of temperature and salinity profiles at the global scale. Nine member ensemble forecasts have been produced for the period 1991-2003 for two starting dates per year in order to assess the impact of the subsurface assimilation in the ocean for initialization. Comparing the results with control simulations (i.e.: without assimilation of subsurface profiles during ocean initialization), we showed that the improved ocean initialization increases the skill in the prediction of tropical Pacific SSTs in our system for boreal winter forecasts. Considering the forecast of the El Ni˜no 1997-1998, the data assimilation in the ocean initial conditions leads to a considerable improvement in the representation of its onset and development. Our results indicate a better prediction of global scale surface climate anomalies for the forecasts started in November, probably due to the improvement in the tropical Pacific. For boreal winter, in both tropics and extra tropics, we show significant increases in the capability of the system to discriminate above normal and below normal temperature anomalies.
    Description: Published
    Description: 2930-2952
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: open
    Keywords: ocean modelling ; global climate models ; seasonal forecast ; coupled models ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2017-04-04
    Description: We investigate the dynamics of turbulent pyroclastic density currents (PDCs) by adopting a 3D, Eulerian-Eulerian multiphase flow model, in which solid particles are treated as a continuum and the grain-size distribution is simplified by assuming two particulate phases. The turbulent sub-grid stress of the gas phase is modelled within the framework of Large-Eddy Simulation (LES) by means of a eddy-viscosity model together with a wall closure. Despite the significant numerical diffusion associated to the upwind method adopted for the Finite-Volume discretization, numerical simulations demonstrate the need of adopting a Sub-Grid Scale (SGS) model, while revealing the complex interplay between the grid and the SGS filter sizes. We also analyse the relationship between the averaged flow dynamic pressure and the action exerted by the PDC on a cubic obstacle, to evaluate the impact of a PDC on a building. Numerical results suggest that the average flow dynamic pressure can be used as a proxy for the force per unit surface acting on the building envelope (Fig. 5), even for such steeply stratified flows. However, it is not possible to express such roportionality as a constant coefficient such as the drag coefficient in a steady-state current. The present results indeed indicate that the large epistemic and aleatory uncertainty on initial and boundary conditions has an impact on the numerical redictions which is comparable to that of grid resolution.
    Description: Unpublished
    Description: (10)
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: open
    Keywords: Large-Eddy Simulation ; pyroclastic density currents ; numerical simulation ; multiphase flows ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 11
    Publication Date: 2017-04-04
    Description: Increased atmospheric carbon dioxide concentration provided warmer atmospheric temperature and higher atmospheric water vapor content, but not necessarily more precipitation. A set of experiments performed with a state-of-the-art coupled general circulation model forced with increased atmospheric CO2 concentration (2, 4 and 16 times the present-day mean value) were analyzed and compared with a control experiment to evaluate the effect of increased CO2 levels on monsoons. Generally, the monsoon precipitation responses to CO2 forcing are largest if extreme concentrations of carbon dioxide are used, but they are not necessarly proportional to the forcing applied. In fact, despite a common response in terms of an atmospheric water vapor increase to the atmospheric warming, two out of the six monsoons studied simulate less or equal summer mean precipitation in the 16xCO2 experiment compared to the intermediate sensitivity experiments. The precipitation differences between CO2 sensitivity experiments and CTRL have been investigated specifying the contribution of thermodynamic and purely dynamic processes. As a general rule, the differences depending on the atmospheric moisture content changes (thermodynamic component) are large and positive, and they tend to be damped by the dynamic component associated with the changes in the vertical velocity. However, differences are observed among monsoons in terms of the role played by other terms (like moisture advection and evaporation) in shaping the precipitation changes in warmer climates. The precipitation increase, even if weak, occurs despite a weakening of the mean circulation in the monsoon regions(‘‘precipitation-wind paradox’’). In particular, the tropical east-west Walker circulation is reduced, as found from velocity potential analysis. The meridional component of the monsoon circulation is changed as well, with larger (smaller) meridional (vertical) scales.
    Description: In press
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: open
    Keywords: carbon dioxide forcing ; monsoon precipitation ; coupled model experiments ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models ; 03. Hydrosphere::03.03. Physical::03.03.02. General circulation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 12
    Publication Date: 2017-04-04
    Description: In this chapter, a review is given of progress to date on an intercomparison project designed to compare and evaluate the ability of climate models to generate tropical cyclones, the Tropical Cyclone climate Model Intercomparison Project(TC-MIP). Like other intercomparison projects, this project aims to evaluate climate models using common metrics in order to make suggestions regarding future development of such models.
    Description: Published
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: restricted
    Keywords: Tropical Cyclones ; general circulation models ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 13
    Publication Date: 2017-04-04
    Description: In this paper, a Bayesian procedure is implemented for the Probability Tsunami Hazard Assessment (PTHA). The approach is general and modular incorporating all significant information relevant for the hazard assessment, such as theoretical and empirical background, analytical or numerical models, instrumental and historical data. The procedure provides the posterior probability distribution that integrates the prior probability distribution based on the physical knowledge of the process and the likelihood based on the historical data. Also, the method deals with aleatory and epistemic uncertainties incorporating in a formal way all sources of relevant uncertainty, from the tsunami generation process to the wave propagation and impact on the coasts. The modular structure of the procedure is flexible and easy to modify and/or update as long as new models and/or information are available. Finally, the procedure is applied to an hypothetical region, Neverland, to clarify the PTHA evaluation in a realistic case.
    Description: In press
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: Bayesian method ; Probability Tsunami Hazard Assessment ; Run-up ; Modular structure ; Seismic sources ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2017-04-04
    Description: This study investigates the possible changes that the greenhouse global warming might generate in the characteristics of the tropical cyclones (TCs). The analysis has been performed using scenario climate simulations carried out with a fully coupled high-resolution global general circulation model. The capability of the model to reproduce a reasonably realistic TC climatology has been assessed by comparing the model results from a simulation of the 20th Century with observations. The model appears to be able to simulate tropical cyclone-like vortices with many features similar to the observed TCs. The simulated TC activity exhibits realistic geographical distribution, seasonal modulation and interannual variability, suggesting that the model is able to reproduce the major basic mechanisms that link the TC occurrence with the large scale circulation. The results from the climate scenarios reveal a substantial general reduction of the TC frequency when the atmospheric CO2 concentration is doubled and quadrupled. The reduction appears particularly evident for the tropical North West Pacific (NWP) and North Atlantic (ATL). In the NWP the weaker TC activity seems to be associated with a reduced amount of convective instabilities. In the ATL region the weaker TC activity seems to be due to both the increased stability of the atmosphere and a stronger vertical wind shear. Despite the generally reduced TC activity, there is evidence of increased rainfall associated with the simulated cyclones. Despite the overall warming of the tropical upper ocean and the expansion of warm SSTs to the subtropics and mid-latitudes, the action of the TCs remains well confined to the tropical region and the peak of TC number remains equatorward of 20° latitude in both Hemispheres. An extended version of this work is in available on Journal of Climate (Gualdi et al.,2008 - DOI:10.1175/2008JCLI1921.1)
    Description: Published
    Description: 287-321
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: open
    Keywords: climate ; tropical cyclones ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 15
    Publication Date: 2017-04-04
    Description: We describe the mineralogy, geochemistry, and mesomicrostructure of fresh subvolcanic blocks erupted during the 5 April 2003 paroxysm of Stromboli (Aeolian Islands, Italy). These blocks represent ∼50 vol.% of the total erupted ejecta and consist of fine- to medium-grained basaltic lithotypes ranging from relatively homogeneous dolerites to strongly or poorly welded magmatic breccias. The breccia components are represented by angular fragments of dolerites entrapped in a matrix of vesiculated (lava-like to scoriae) crystal-rich (CR) basalt. All of the studied blocks are cognates with the CR basalt of the normal Strombolian activity or lavas and they are often coated by a few-centimeter thick layer of crystal-poor (CP) basaltic pumice erupted during the paroxysm. We suggest that they result from the rapid increase of pressure and related subvolcanic rock failure that occurred shortly before the 5 April 2003 explosion, when the uppermost portion of the edifice inflated and suffered brecciation as the result of the sudden rise of the gas-rich CP basalt that triggered the eruption. Dolerites and magmatic matrix of the breccias show major and trace element compositions that match those of the CR basalts erupted during normal Strombolian activity and effusive events at Stromboli volcano. Dolerites consist of (a) phenocrysts normally found in the CR basalts and (b) late-stage magmatic minerals such as sanidine, An60-28 plagioclase, Fe–Mn-rich olivines (Fo68-48), phlogopite, apatite, and opaque mineral pairs (magnetite and ilmenite), most of which are never found both in lava flows and scoriae erupted during the persistent explosive activity that characterizes typical Strombolian behavior. Subvolcanic crystallization of the Stromboli CR magma, leading to slowly cooled equivalents of basalts, could result from transient drainage of the magma from the summit craters to lower levels. Fingering and engulfing of the material that collapsed from the summit crater floor into the shallow basaltic system during the late evening of 28 December 2002 coupled with the short break in the summit persistent explosions between December 2002 and March 2003 permitted the CR magma pockets to solidify as dolerites, which were confined to the uppermost portion of the system and thus not involved in the ongoing flank effusive activity. Crystal size distribution of the basaltic blocks and crystallization of the finer-grained (〈0.1 mm) mafic minerals of the dolerites over a time interval of ∼100 days closely agrees with the above interpretation. Vesicle filling (miarolitic cavities) locally found in some dolerites, with minerals deposited as vapor-phase crystallization is a result of continuous gas percolation through the rocks of the uppermost portion of the volcanic system. Poorly welded magmatic breccias formed during syn-eruptive processes of 5 April 2003, when the paroxysm strongly shattered the shallow subvolcanic system and many dolerite fragments were entrapped in the CR magma. In contrast, the high degree of welding between the dolerite clasts and the CR basaltic matrix in the strongly welded magmatic breccias provides a snapshot of subvolcanic intrusions of the CR basalt into the dolerite when, after a 2-month break in activity, CR magmas started to rise again to the summit craters. Blocks similar to these subvolcanic ejecta of 5 April 2003 were also erupted during previous paroxysms (e.g., 1930) suggesting that changes in the usual Strombolian activity (e.g., short breaks in the persistent mild explosions and/or flank effusive activity) lead to transient crystallization of dolerites in the shallow plumbing system.
    Description: Published
    Description: 795-813
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Basalt ; Subvolcanic crystallization ; Dolerite ; Magmatic breccia ; Stromboli ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
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  • 16
    Publication Date: 2017-04-04
    Description: Natural precipitation and water samples from passive devices were collected at Mt. Vesuvius and Vulcano Island, Italy, during the period 2004–2006, in order to investigate its possible interactions with fumarolic gases. Evidence of chemical reactions between fumarolic fluids and rain samples before and after its deposition into the sampling devices was found at Vulcano Island. Very low pH values (down to 2.5) and significant amounts of chlorine and sulfate (up to 22 mEq/l) were measured at sampling points located close to the fumarolic field. In contrast, anthropogenic contributions and/or dissolution of aerosols (both maritime and continental) influence the chemistry of rainwaters at Mt. Vesuvius, which show inter-annual variations that are highly consistent with those recorded at the coastal site at Vulcano Island. Chemistry of waters directly exposed to fumarolic fluids may then give useful information about its temporal evolution, holding the signal of the ‘‘maximum’’ chemical event occurred in the meanwhile. In addition, the observation of the health status of vegetation colonizing the immediate surroundings of the fumarolic fields, due to its strong dependence on the interactions with these fluids, may work as a possible biomarker of volcanic activity
    Description: In press
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: N/A or not JCR
    Description: reserved
    Keywords: Geochemistry ; Precipitation ; Fumarole ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
    Publication Date: 2017-04-04
    Description: In the last years, unmanned aerial vehicle (UAV) systems have become very attractive for various commercial, industrial, public, scientific, and military operations. Potential tasks include pipeline inspection, dam surveillance, photogrammetric survey, infrastructure maintenance, inspection of flooded areas, fire fighting, terrain monitoring, volcano observations, and any utilization which requires land recognition with cameras or other sensors. The flying capabilities provided by UAVs require a welltrained pilot to be fully and effectively exploited; moreover the flight range of the piloted helicopter is limited to the line-of-sight or the skill of the pilot to detect and follow the orientation of the helicopter. Such issues are even more important considering that the vehicle will carry and operate automatically a camera used for a photogrammetric survey. All this has motivated research and design for autonomous guidance of the vehicle which could both stabilize and guide the helicopter precisely along a reference path. The constant growth of research programs and the technological progress in the field of navigation systems, as denoted by the production of more and more performing global positioning systems integrated with inertial navigation sensors, allowed a strong cost reduction and payload miniaturization, making the design of low-cost UAV platforms more feasible and attractive. In this paper, we present the results of a flight simulation system developed for the setup of the vehicle’s servos, which our autonomous guidance system, as well as the module for camera photogrammetric image acquisition and synchronization, will be based on. Building a simulated environment allows to evaluate in advance what the main issues of a complex control system are to avoid damage of fragile and expensive instruments as the ones mounted on a model helicopter and to test methods for synchronization of the camera with flight parameters.
    Description: Published
    Description: 85-95
    Description: 1.10. TTC - Telerilevamento
    Description: N/A or not JCR
    Description: reserved
    Keywords: UAV ; Model helicopter ; Kalman filter ; MEMS ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Publication Date: 2017-04-04
    Description: Panarea volcano (Aeolian Islands, Italy) was considered extinct until November 3, 2002, when a submarine gas eruption began in the area of the islets of Lisca Bianca, Bottaro, Lisca Nera, Dattilo, and Panarelli, about 2.5 km east of Panarea Island. The gas eruption decreased to a state of low degassing by July 2003. Before 2002, the activity of Panarea volcano was characterized by mild degassing of hydrothermal fluid. The compositions of the 2002 gases and their isotopic signatures suggested that the emissions originated from a hydrothermal/geothermal reservoir fed by magmatic fluids. We investigate crustal deformation of Panarea volcano using the global positioning system (GPS) velocity field obtained by the combination of continuous and episodic site observations of the Panarea GPS network in the time span 1995–2007. We present a combined model of Okada sources, which explains the GPS results acquired in the area from December 2002. The kinematics of Panarea volcano show two distinct active crustal domains characterized by different styles of horizontal deformation, supported also by volcanological and structural evidence. Subsidence on order of several millimeters/year is affecting the entire Panarea volcano, and a shortening of 10−6 year−1 has been estimated in the Islets area. Our model reveals that the degassing intensity and distribution are strongly influenced by geophysical-geochemical changes within the hydrothermal/geothermal system. These variations may be triggered by changes in the regional stress field as suggested by the geophysical and volcanological events which occurred in 2002 in the Southern Tyrrhenian area.
    Description: Published
    Description: 609-621
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: GPS monitoring ; Model ; Gas eruption ; Active volcanism ; Aeolian arc ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 19
    Publication Date: 2017-04-04
    Description: The Irpinia Seismic Network (ISNet) is deployed in Southern Apennines along the active fault system responsible for the 1980, November 23, MS 6.9 Campania-Lucania earthquake. It is comprised of 28 stations and covers an area of about 100x70 km2. Each site is equipped with a 1-g full-scale accelerometer and a short-period velocimeter. Thanks to its design characteristics, i.e. the wide dynamic recording range and the high density of stations, the ISNet network is mainly devoted to estimating in real-time the earthquake location and magnitude from low- to high- magnitude events, and to providing ground-motion parameters to get some insights about the ground shaking expected. Moreover, the availability of high-quality data allows studying the source processes related to the seismogenetic structures in the area. The network layout, the data communication system and protocols and the main instrumental features are described in the paper. Most of the data analysis is performed through the Earthworm software package, that also provides the automatic earthquake locations, while custom software has been developed for real-time computation of the source parameters and shaking maps. Technical details about these procedures are given in the article. The data collected at the ISNet stations are available upon request.
    Description: Published
    Description: 1105-1129
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: early warning ; real time seismology ; Irpinia region ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 20
    Publication Date: 2017-04-04
    Description: In the present work we analyse one of the active normal faults affecting the central Apennines, i.e. the Mt. Morrone normal fault system. This tectonic structure, which comprises two parallel, NW-SE trending fault segments, is considered as potentially responsible for earthquakes of magnitude C 6.5 and its last activation probably occurred during the second century AD. Structural observations performed along the fault planes have allowed to define the mainly normal kinematics of the tectonic structure, fitting an approximately N 20 trending extensional deformation. Geological and geomorphological investigations performed along the whole Mt. Morrone south-western slopes permitted us to identify the displacement of alluvial fans, attributed to Middle and Late Pleistocene by means of tephro-stratigraphic analyses and geomorphological correlations with dated lacustrine sequences, along the western fault branch. This allowed to evaluate in 0.4 ± 0.07 mm/year the slip rate of this segment. On the other hand, the lack of synchronous landforms and/or deposits that can be correlated across the eastern fault segment prevented the definition of the slip rate related to this fault branch. Nevertheless, basing on a critical review of the available literature dealing with normal fault systems evolution, we hypothesised a total slip rate of the fault system in the range of 0.4 ± 0.07 to 0.8 ± 0.09 mm/year. Moreover, basing on the length at surface of the Mt. Morrone fault system (i.e. 22–23 km) we estimated the maximum expected magnitude of an earthquake that might originate along this tectonic structure in the order of 6.6–6.7.
    Description: Dipartimento della Protezione Civile Nazionale
    Description: In press
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: Active fault ; Slip rate ; Maximum expected magnitude ; Continental stratigraphy ; Sulmona basin ; Central Apennines ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 21
    Publication Date: 2017-04-04
    Description: The South Atlantic magnetic Anomaly (SAA) is an important feature of the present geomagnetic field. In this paper we model the space-time evolution of this anomaly for the last 400 years in terms of the resultant between a decrease of a global axial dipole and an increase of a virtual local monopole source. Some characteristics of this evolution are investigated and some considerations are made on the light of a possible special state of the global geomagnetic field dynamical regime. Among the possible speculations, one is made regarding the topography of the core-mantle boundary (CMB) and its possible aspect underneath the SAA region in terms of simple sinusoidal undulations met by the monopole source during its centennial motion.
    Description: In press
    Description: 1.6. Osservazioni di geomagnetismo
    Description: 3.4. Geomagnetismo
    Description: JCR Journal
    Description: open
    Keywords: South Atlantic Anomaly ; equivalent monopole source ; Earth core topography ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.04. Magnetic anomalies
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 22
    Publication Date: 2017-04-04
    Description: Moderate-magnitude shallow earthquakes in the Atlantic Ocean, hundreds of kilometres southwest of Lisbon, can generate efficient suboceanic Rayleigh waves (SRW) that are well recorded in Portugal. Here we compare moderate-size earthquakes recorded by seismic stations in Portugal with the Tyrrhenian Sea earthquakes recorded in peninsular Italy where SRW were recently observed. In spite of a different behaviour of high frequencies due to the different tectonic setting of the two areas, similar results are found in the intermediate-period range, suggesting that this effect, if extrapolated to a magnitude larger than 8, could be devastating at regional distance in terms of ground motion amplitude and duration. Through 1D models, we explore the hypothesis that the high level of destruction and the long duration of shaking felt during the Great 1755 Lisbon earthquake were caused by SRW. In this preliminary study, we check the role of critical model parameters. We find that duration and amplitude are largest when the average thickness of the water layer is 2 km and shear-wave velocity of the ocean floor is close to the speed of sound in the water. Both conditions are realistic for a source in the Atlantic Ocean, few hundreds of kilometres southwest of Lisbon. Moreover, the propagation of SRW at regional distances accounts for durations of more than ten minutes as the effect of a single large earthquake.
    Description: Published
    Description: 283-295
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: open
    Keywords: ground motion ; surface waves ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 23
    Publication Date: 2017-04-04
    Description: On 30 December 2002, a 25-30 × 106 m3 landslide on the NW flank of Stromboli volcano produced a tsunami that caused relevant damage to the Stromboli village and to the neighboring islands of the Aeolian archipelago. The NW flank of Stromboli has been the site of several, cubic kilometer-scale, landslides during the past 13 ka. In this paper we present sedimentological and compositional data of deep-sea cores recovered from a site located about 24 km north of the island. Our preliminary results indicate that: (i) turbidity currents were effectively generated by the large-scale failures and (ii) volcanogenic turbidity current deposits retain clues of the landslide source and slope failure dynamics. By analogy with Hawaii and the Canary islands we confirm that deep-sea sediments can be effectively used to assess the age and scale of past landslide events giving an important contribution to the tsunami hazard assessment of this region.
    Description: Unpublished
    Description: -
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: reserved
    Keywords: Landslide ; turbidite ; tsunami ; Stromboli ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 24
    Publication Date: 2017-04-04
    Description: Previous works based mainly on strong-motion recordings of large Japanese earthquakes showed that site amplification and soil fundamental frequency could vary over long and short time scales. These phenomena were attributed to non-linear soil behaviour: the starting fundamental frequency and amplification were both instantaneously decreasing and then recovering for a time varying from few seconds to several months. The recent April 6, 2009 earthquake (M W 6.3), occurred in the L’Aquila district (central Italy), gave us the possibility to test hypotheses on time variation of amplification function and soil fundamental frequency, thanks to the recordings provided by a pre-existing strong-motion array and by a large number of temporary stations. We investigated the intra- and inter-event soil frequency variations through different spectral analyses, including time-frequency spectral ratios and S-Transform (Stockwell et al. in IEEE Trans Signal Process 44:998–1001, 1996). Finally, analyses on noise recordings were performed, in order to study the soil behaviour in linear conditions. The results provided puzzling evidences. Concerning the long time scale, little variation was observed at the permanent stations of the Aterno Valley array. As for the short time-scale variation, the evidence was often contrasting, with some station showing a time-varying behavior, while others did not change their frequency with respect to the one evaluated from noise measurements. Even when a time-varying fundamental frequency was observed, it was difficult to attribute it to a classical, softening non-linear behaviour. Even for the strongest recorded shocks, with peak ground acceleration reaching 0.7 g, variations in frequency and amplitude seems not relevant from building design standpoint. The only exception seems to be the site named AQV, where the analyses evidence a fundamental frequency of the soil shifting from 3 Hz to about 1.5 Hz during the mainshock.
    Description: Published
    Description: 869-892
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: Strong motion ; Subsoil non-linearity ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 25
    Publication Date: 2017-04-04
    Description: A temporary seismic network composed of 11 stations was installed in the city of Potenza (Southern Italy) to record local and regional seismicity within the context of a national project funded by the Italian Department of Civil Protection (DPC). Some stations were moved after a certain time in order to increase the number of measurement points, leading to a total of 14 sites within the city by the end of the experiment. Recordings from 26 local earthquakes (Ml 2.2−3.8 ) were analyzed to compute the site responses at the 14 sites by applying both reference and non-reference site techniques. Furthermore, the Spectral Intensity (SI) for each local earthquake, as well as their ratios with respect to the values obtained at a reference site, were also calculated. In addition, a field survey of 233 single station noise measurements within the city was carried out to increase the information available at localities different from the 14 monitoring sites. By using the results of the correlation analysis between the horizontal-to-vertical spectral ratios computed from noise recordings (NHV) at the 14 selected sites and those derived by the single station noise measurements within the town as a proxy, the spectral intensity correction factors for site amplification obtained from earthquake analysis were extended to the entire city area. This procedure allowed us to provide a microzonation map of the urban area that can be directly used when calculating risk scenarios for civil defence purposes. The amplification factors estimated following this approach show values increasing along the main valley toward east where the detrital and alluvial complexes reach their maximum thickness.
    Description: Published
    Description: 493-516
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: restricted
    Keywords: site effect ; seismic noise ; spectral intensity ; correlation ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 26
    Publication Date: 2017-04-04
    Description: We present results of a multi-temporal analysis of airborne LiDAR data collected between 2006 and 2010 on the 3 km long active Montaguto landslide (Italy). Digital Terrain Models are constructed from data acquired on May 2006, July 2009, April 2010 and June 2010. The spatial distribution of selected morphometric parameters and the statistical analysis of the temporal variations of such parameters allow us to reconstruct the evolution of the landslide. We recognize zones of uplift and subsidence, estimate the volumes of removed or accumulated material, and determine the average rate of vertical and horizontal displacement. We also map the deformations structures and provide new insights on the sliding mechanisms. Zones in which the topographic features change due to handling/removal work are also analyzed. The approach proposed here provides new insight on the use of airborne LiDAR in the surveillance strategies of landslides and other gravity-controlled processes.
    Description: Published
    Description: 147-151
    Description: 1.10. TTC - Telerilevamento
    Description: 5.5. TTC - Sistema Informativo Territoriale
    Description: restricted
    Keywords: LiDAR ; Multi-temporal analysis ; Gravity processes ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 27
    Publication Date: 2017-04-04
    Description: Active volcanoes characterized by open conduit conditions generate sonic and infrasonic signals, whose investigation provides useful information for both monitoring purposes and studying the dynamics of explosive processes. In this work, we discuss the automatic procedures implemented for a real-time application to the data acquired by a permanent network of five infrasound stations running at Mt. Etna volcano. The infrasound signals at Mt. Etna consist in amplitude transients, called infrasound events. The adopted procedure uses a multi-algorithm approach for event detection, counting, characterization and location. It is designed for an efficient and accurate processing of infrasound records provided by single-site and array stations. Moreover, the source mechanism of these events can be investigated off-line or in near real-time by using three different models: (1) Strombolian bubble; (2) resonating conduit and (3) Helmholtz resonator. The infrasound waveforms allow us to choose the most suitable model, to get quantitative information about the source and to follow the time evolution of the source parameters.
    Description: Published
    Description: 1215–1231
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Infrasound ; monitoring system ; Mt. Etna volcano ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
    Publication Date: 2017-04-04
    Description: We exploit S-wave spectral amplitudes from 112 aftershocks (3.0 ≤ ML ≤ 5.3) of the L’Aquila 2009 seismic sequence recorded at 23 temporary stations in the epicentral area to estimate the source parameters of these events, the seismic attenuation characteristics and the site amplification effects at the recording sites. The spectral attenuation curves exhibit a very fast decay in the first few kilometers that could be attributed to the large attenuation of waves traveling trough the highly heterogeneous and fractured crust in the fault zone of the L’Aquila mainshock. The S-waves total attenuation in the first 30 km can be parameterized by a quality factor QS(f) = 23f^0.58 obtained by fixing the geometrical spreading to 1/R. The source spectra can be satisfactorily modeled using the omega-square model that provides stress drops between 0.3 and 60 MPa with a mean value of 3.3±2.8 MPa. The site responses show a large variability over the study area and significant amplification peaks are visible in the frequency range from 1 to more than 10 Hz. Finally, the vertical component of the motion is amplified at a number of sites where, as a consequence, the horizontal-to-vertical spectral ratios (HVSR) method fails in detecting the amplitude levels and in few cases the resonance frequencies.
    Description: Published
    Description: 717-739
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: Generalized Inversion Technique ; 2009 L'Aquila earthquake ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 29
    facet.materialart.
    Unknown
    Springer
    Publication Date: 2017-04-04
    Description: Previous research works proved the existence of a synchronization between speech and holds in adults and in 9 year old children with a rich linguistic vocabulary and advanced language skills. When and how does this synchrony develop during child language acquisition? Could it be observed also in children younger than 9? The present work aims to answer the above questions reporting on the analysis of narrations produced by three different age groups of Italian children (9, 5 and 3 year olds). Measurements are provided on the amount of synchronization between speech pauses and holds in the three different groups, as a function of the duration of the narrations. The results show that, as far as the reported data concerns, in children, as in adults, holds and speech pauses are to a certain extent synchronized and play similar functions, suggesting that they may be considered as a multi-determined phenomenon exploited by the speaker under the guidance of a unified planning process to satisfy a communicative intention. In addition, considering the role that speech pauses play in communication, we speculate on the possibility that holds may serve to similar purposes supporting the hypothesis that gestures as speech are an expressive resource that can take on different functions depending on the communicative demand. While speech pauses are likely to play the role of signalling mental activation processes aimed at replacing the “old spoken content” of the communicative plan with a new one, holds may signal mental activation processes aimed at replacing the “old visible bodily action” with new ones reflecting the representational and/or propositional contribution of gestures to the new communicative plan.
    Description: Published
    Description: 252-272
    Description: 5.9. Formazione e informazione
    Description: restricted
    Keywords: Speech pauses, holds, synchrony, child narrations ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 30
    Publication Date: 2017-04-04
    Description: The selection of specific elastic response spectra according to soil categories is the easiest way to account for site effects in engineering projects and general-purpose hazard maps. Most of the international seismic codes make use of the average shear wave velocity of the upper 30 m (Vs,30) to discriminate soil categories, although some doubts arose about the capability of Vs,30 to predict actual soil amplification. In this work we propose two soil classifications in which the soil fundamental frequency (f0) becomes either an alternative or a complement to Vs,30. The performance of the derived categorizations is achieved through the estimation of the standard deviation associated to ground motion prediction equations of acceleration response spectra, considering recordings extracted from the Italian strong motion data base. The results indicate that there is a significant reduction of the standard deviation when the classification is based on the couple of variables Vs,30–f0, although a classification based of the single f0 also leads to satisfactory results, comparable with those obtained assuming a classification scheme based on Vs,30.
    Description: Published
    Description: 1877-1898
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: site effects ; soil classification ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 31
    Publication Date: 2017-04-03
    Description: A global ocean three-dimensional variational data assimilation system was developed with the aim of assimilating along-track sea level anomaly observations, along with in situ observations from bathythermographs and conventional sea stations. All the available altimetric data within the period October 1992–January 2006 were used in this study. The sea level corrections were covariated with vertical profiles of temperature and salinity according to the bivariate definition of the background-error vertical covariances. Sea level anomaly observational error variance was carefully defined as a sum of instrumental, representativeness, observation operator, and mean dynamic topography error variances. The mean dynamic topography was computed from the model long-term mean sea surface height and adjusted through an optimal interpolation scheme to account for observation minus first-guess biases. Results show that the assimilation of sea level anomaly observations improves the model sea surface height skill scores as well as the subsurface temperature and salinity fields. Furthermore, the estimate of the tropical and subtropical surface circulation is clearly improved after assimilating altimetric data. Nonnegligible impacts of the mean dynamic topography used have also been found: compared to a gravimeter-based mean dynamic topography the use of the mean dynamic topography discussed in this paper improves both the consistency with sea level anomaly observations and the verification skill scores of temperature and salinity in the tropical regions. Furthermore, the use of a mean dynamic topography computed from the model long-term sea surface height mean without observation adjustments results in worsened verification skill scores and highlights the benefits of the current approach for deriving the mean dynamic topography.
    Description: European Commission WP4 Fondazione Cassa di Risparmio di Bologna Cnes
    Description: Published
    Description: 738-754
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: 4.6. Oceanografia operativa per la valutazione dei rischi in aree marine
    Description: 5.4. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: JCR Journal
    Description: partially_open
    Keywords: Data assimilation ; Satellite observations ; Ocean models ; Sea level ; In situ observations ; Variational analysis ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models ; 03. Hydrosphere::03.01. General::03.01.04. Ocean data assimilation and reanalysis
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  • 32
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    Springer
    Publication Date: 2017-04-04
    Description: n/a
    Description: Published
    Description: 125-127
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: restricted
    Keywords: Core-mantle boundary topography ; Seismology ; 04. Solid Earth::04.01. Earth Interior::04.01.03. Mantle and Core dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 33
    Publication Date: 2017-04-04
    Description: Global-scale variations in the climate system over the last half of the twentieth century. including long-term increases in global-mean near-surface temperatures. are consistent with concurrent human-induced emissions of radiatively active gases and aerosols. However, such consistency does not preclude the possible influence of other forcing agents, including internal modes of climate variability or unaccounted for aerosol effects. To test whether other unknown forcing agents may have contributed to multidecadal increases in global-mean near-surface temperatures from 1950 to 2000. data pertaining to observed changes in global-scale sea surface temperatures and observed changes in radiatively active atmospheric constituents are incorporated into numerical global climate models. Results indicate that the radiative forcing needed to produce the observed long-term trends in sea surface temperatures-and global-mean near-surface temperatures-is provided predominantly by known changes in greenhouse gases and aerosols. Further, results indicate that less than 10% of the long-term historical increase in global-mean near-surface temperatures over the last half of the twentieth century could have been the result of internal climate variability. In addition. they indicate that less than 25% of the total radiative forcing needed to produce the observed long-term trend in global-mean near-surface temperatures could have been provided by changes in net radiative forcing from unknown sources (either positive or negative). These results, which are derived from simple energy balance requirements. emphasize the important role humans have played in modifying the global climate over the last half of the twentieth century.
    Description: Published
    Description: 7163-7172
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: restricted
    Keywords: climate forcing ; temperature increase ; AGCM ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
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  • 34
    facet.materialart.
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    American Meteorological Society
    Publication Date: 2020-02-24
    Description: An aquaplanet model is used to study the nature of the highly persistent low-frequency waves that have been observed in models forced by zonally symmetric boundary conditions. Using the Hayashi spectral analysis of the extratropical waves, the authors find that a quasi-stationary wave 5 belongs to a wave packet obeying a well-defined dispersion relation with eastward group velocity. The components of the dispersion relation with k ≥ 5 baroclinically convert eddy available potential energy into eddy kinetic energy, whereas those with k 〈 5 are baroclinically neutral. In agreement with Green’s model of baroclinic instability, wave 5 is weakly unstable, and the inverse energy cascade, which had been previously proposed as a main forcing for this type of wave, only acts as a positive feedback on its predominantly baroclinic energetics. The quasi-stationary wave is reinforced by a phase lock to an analogous pattern in the tropical convection, which provides further amplification to the wave. It is also found that the Pedlosky bounds on the phase speed of unstable waves provide guidance in explaining the latitudinal structure of the energy conversion, which is shown to be more enhanced where the zonal westerly surface wind is weaker. The wave’s energy is then trapped in the waveguide created by the upper tropospheric jet stream. In agreement with Green’s theory, as the equator-to-pole SST difference is reduced, the stationary marginally stable component shifts toward higher wavenumbers, while wave 5 becomes neutral and westward propagating. Some properties of the aquaplanet quasi-stationary waves are found to be in interesting agreement with a low frequency wave observed by Salby during December–February in the Southern Hemisphere so that this perspective on low frequency variability, apart from its value in terms of basic geophysical fluid dynamics, might be of specific interest for studying the earth’s atmosphere.
    Description: Published
    Description: 1023–1040.
    Description: JCR Journal
    Description: restricted
    Keywords: Boundary conditions ; 03. Hydrosphere::03.02. Hydrology::03.02.99. General or miscellaneous
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  • 35
    Publication Date: 2020-02-24
    Description: The S1 pecial Issue of the Bulletin of Earthquake Engineering devoted to the new 2 Italian strong motion database ITACA (ITalian ACelerometric Archive) is introduced in this 3 foreword. An overview of the papers published in this issue is presented, providing an idea of 4 the number of problems encountered in the compilation of a database as rich of information 5 as ITACA, of the solutions adopted and of the possible research and practical applications. 6 Most of the contents, though specifically addressed to ITACA and to its accelerograms, can 7 be usefully thought of as an exemplification of approaches and methods that can be used for, 8 and extended to, similar databases in other countries
    Description: Published
    Description: 1717-1721
    Description: 5.2. TTC - Banche dati di sismologia strumentale
    Description: JCR Journal
    Description: reserved
    Keywords: Strong motion database ; ITACA ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
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  • 36
    Publication Date: 2017-04-04
    Description: Direct measurements of the geomagnetic field have been made for more than 400 years, beginning with individual determinations of the angle between geographic and magnetic North. This was followed by the start of continuous time series of full vector measurements at geomagnetic observatories and the beginning of geomagnetic repeat stations surveys in the 19th century. In the second half of the 20th century, true global coverage with geomagnetic field measurements was accomplished by magnetometer payloads on low-Earth-orbiting satellites. This article describes the procedures and instruments for magnetic field measurements on ground and in space and covers geomagnetic observatories, repeat stations, automatic observatories, satellites and historic observations. Special emphasis is laid on the global network of geomagnetic observatories.
    Description: Published
    Description: 1.6. Osservazioni di geomagnetismo
    Description: JCR Journal
    Description: reserved
    Keywords: Geomagnetic field ; Observations ; Geomagnetic observatories ; Magnetic satellite missions ; 04. Solid Earth::04.05. Geomagnetism::04.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 37
    Publication Date: 2017-04-04
    Description: The 2001 and 2002–2003 flank eruptions on Mount Etna (Italy) were characterized by intense explosive activity which led to the formation of two large monogenetic scoria cones (one from each eruption) on the upper southern flank of the volcano. Continuous monitoring of Etna, especially during flank eruptions, has provided detailed information on the growth of these cones. They differ in genesis, shape, and size. A set of high resolution (1 m) digital elevation models (DEMs) derived from light detection and ranging (LIDAR) data collected during four different surveys (2004, 2005, 2006, and 2007) has been used to map morphology and to extract the morphometric parameters of the scoria cones. By comparing LIDAR-derived DEMs with a pre-eruption (1998) 10 m DEM, the volume of the two scoria cones was calculated for the first time. Comparison of the LIDAR-derived DEMs revealed in unprecedented detail morphological changes during scoria cone degradation. In particular, the morphologically more exposed and structurally weaker 2002–2003 cone was eroded rapidly during the first few years after its emplacement mainly due to gravitational instability of slopes and wind erosion.
    Description: Published
    Description: 1209–1222
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna ; Scoria cone evolution ; Erosion ; LIDAR ; DEM ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 38
    Publication Date: 2017-04-04
    Description: We have studied two velocity-depth models with the aim of outlining the behavior of a velocity reversal in the top layer, which is associated with the stiff Brecce de L’Aquila unit (BrA). In this setting, the SMTH model is topped by a layer with about 2:1 impedance contrast with the underlying layer while the NORV model has no velocity reversal. We have simulated the propagation of SH and P-SV wavefields in the range 0–10 Hz for incidence 0◦ –90◦ . Earthquake spectral ratios of the horizontal and vertical components at six sites in L’Aquila downtown are compared to corresponding syn- thetics spectral ratios. The vertical component of P-SV synthetics enables us to investigate a remarkable amplification effect seen in the vertical component of the recorded strong motion. Sites AQ04 and AQ05 are best matched by synthetics from the NORV model while FAQ5 and AQ06 have a better match with synthetics spectral ratios from the SMTH model. All simulations show this behavior systematically, with horizontal and near-horizontal incident waves predicting the overall pattern of matches more clearly than vertical and near-vertical incidence. The model inferences are in agreement with new geological data reporting lateral passages in the top layer from the stiff BrA to softer sediments. Matches are good in terms of frequency of the first amplification peak and of spectral amplitude: the horizontal compo-nents have spectral ratio peaks predominantly at 0.5 Hz in the simulations and at 0.7 Hz in the data, both with amplitudes of 4, while the vertical component spectral ratios reach values of 6 at frequencies of about 1 Hz in both data and simulations. The vertical component spectral ratios are very well matched using Rayleigh waves with incidence at 90◦ . The NORV model without the velocity reversal predicts spectral ratio peaks for the horizontal components at frequencies up to 6 Hz. The reversal of velocity acts as a low-pass frequency filter on the horizontal components reducing the amplification effect of the sediment filled valley.
    Description: Published
    Description: 761-781
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: site effect, 2D synthetic seismograms, spectral ratios, reversal of velocity, L'Aquila ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 39
    Publication Date: 2017-04-04
    Description: In this work, we investigate the site amplification effects observed in the Norcia plain, Central Italy. Data from 30 selected local earthquakes (2 ≤ Ml ≤ 4.1) recorded by a temporary seismic network composed by 15 stations, are analyzed to determine the spa- tial variability of site effects. Both the Horizontal-to-Vertical spectral ratio and the Standard Spectral Ratio techniques are applied to estimate the site amplification effects. The results show that most of the sites in the valley are affected by strong amplifications (up to a factor of 20) in the frequency range 0.5–5 Hz. The value of the fundamental frequency of resonance is strictly dependent on the location within the basin and on the sediment thickness. Strong amplifications also affect the vertical components. The time-frequency analysis performed on a station located inside the basin shows the presence of a large spectral amplitudes after the S-wave phase, not observed on a station located on the bedrock, suggesting the pres- ence of locally generated wave trains. Then, in agreement with earlier observations for other alluvial basins in Central Italy, 2D–3D effects play an important role in determining the site amplification effects in Norcia.
    Description: Published
    Description: 1941-1959
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: reserved
    Keywords: site effects ; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 40
    Publication Date: 2017-04-04
    Description: In this work the authors investigate possible changes in the distribution of heavy precipitation events under a warmer climate, using the results of a set of 20 climate models taking part in the Coupled Model Intercomparison Project phase 5 effort (CMIP5). Future changes are evaluated as the difference between the last four decades of the 21st and the 20th Century assuming the Representative Concentration Pathway RCP8.5 scenario. As a measure of the width of the right tail of the precipitation distribution, we use the difference between the 99th and the 90th percentiles. Despite a slight tendency to underestimate the observed heavy precipitation, the considered CMIP5 models well represent the observed patterns in terms of the ensemble average, during both summer and winter seasons for the 1997-2005 period. Future changes in average precipitation are consistentwith previous findings based on CMIP3 models. CMIP5 models show a projected increase for the end of the twenty-first century of the width of the right tail of the precipitation distribution, particularly pronounced over India, South East Asia, Indonesia and Central Africa during borealsummer, as well as over South America and southern Africa during boreal winter.
    Description: Published
    Description: 7902–7911
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: open
    Keywords: precipitation ; extreme events ; climate change ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 41
    Publication Date: 2017-04-04
    Description: We performed geodetic strain rate analyses in southern Italy, using new GPS velocities. Two-dimensional strain and rotation rate fields were estimated and results show that most of the shortening is distributed in the northern Sicily offshore. Extension becomes more evident and comparable with shortening on the eastern side of the same margin, and greater in the eastern Sicily offshore. Principal shortening and extension rate axes are consistent with longterm geological features: seismic reflection profiles show both active compressive and extensional faults affecting Pleistocene strata. We show evidence for contemporaneous extension and transtension in the Cefalu` Basin. Combining geodetic data and geological features point to the coexistence of independent geodynamic processes, i.e., the active E–W backarc spreading in the hangingwall of the Apennines subduction zone and shortening along the southern margin of the Tyrrhenian backarc basin operated by the NNW-motion of Africa relative to Eurasia.
    Description: Published
    Description: 1915-1924
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: restricted
    Keywords: Southern Tyrrhenian Sea ; GPS-derived strain rate ; Seismic reflection profiles ; Coexisting tectonics ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 42
    Publication Date: 2017-04-04
    Description: The Italian Strong Motion Database, ITACA, was developed within projects 2 S6 and S4, funded in the framework of the agreements between the Italian Department of 3 Civil Protection (Dipartimento della Protezione Civile, DPC) and the Istituto Nazionale di 4 Geofisica e Vulcanologia (INGV), starting from 2005. The alpha version of the database 5 was released in 2007 and subsequently upgraded to version 1.0 after: (i) including the most 6 recent strongmotion data (from2005 to 2007) recorded in Italy, in addition to the 2008 Parma 7 earthquake, M 5.4, and the M 4.0, 2009 Abruzzo seismic events; (ii) processing the raw 8 strong motion data using an updated procedure; (iii) increasing the number of stations with a 9 measured shear wave velocity profile; (iv) improving the utilities to retrieve time series and 10 ground motion parameters; (v) implementing a tool for selecting time series in agreement 11 with design-response spectra; (vi) compiling detailed station reports containing miscella12 neous information such as photo, maps and site parameters; (vii) developing procedures for 13 the automatic generation of station reports and for the updating of the header files. After such 14 improvements, ITACA 1.0 was published at the web site http://itaca.mi.ingv.it, in 2010. It 15 presently contains 3,955 three-component waveforms, comprising the most complete cata16 logue of the Italian accelerometric records in the period 1972–2007 (3,562 records) and the 17 strongest events in the period 2008–2009. Records were mainly acquired by DPC through its 18 Accelerometric National Network (RAN) and, in few cases, by local networks and temporary 19 stations or networks. This paper introduces the published version of the Italian StrongMotion 20 database (ITACA version 1.0) together with main improvements and new functionalities.
    Description: Published
    Description: 1723-1739
    Description: 5.2. TTC - Banche dati di sismologia strumentale
    Description: JCR Journal
    Description: open
    Keywords: italian strong motion data ; web-portal ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 43
    Publication Date: 2017-04-04
    Description: Using a lava flow emplacement model and a satellite-based land cover classification, we produce a map to allow assessment of the type and quantity of natural, agricultural and urban land cover at risk from lava flow invasion. The first step is to produce lava effusion rate contours, i.e., lines linking distances down a volcano’s flank that a lava flow will likely extend if fed at a given effusion rate from a predetermined vent zone. This involves first identifying a vent mask and then running a downhill flow path model from the edge of every pixel around the vent mask perimeter to the edge of the DEM. To do this, we run a stochastic model whereby the flow path is projected 1,000 times from every pixel around the vent mask perimeter with random noise being added to the DEM with each run so that a slightly different flow path is generated with each run. The FLOWGO lava flow model is then run down each path, at a series of effusion rates, to determine likely run-out distance for channel-fed flow extending down each path. These results are used to plot effusion rate contours. Finally, effusion rate contours are projected onto a land classification map (produced from an ASTER image of Etna) to assess the type and amount of each land cover class falling within each contour. The resulting maps are designed to provide a quick look-up capability to assess the type of land at risk from lava extending from any location at a range of likely effusion rates. For our first (2,000 m) vent zone case used for Etna, we find a total of area of ~680 km2 is at risk from flows fed at 40 m3 s−1, of which ~6 km2 is urban, ~150 km2 is agriculture and ~270 km2 is grass/woodland. The model can also be run for specific cases, where we find that Etna’s 1669 vent location, if active today, would likely inundate almost 11 km2 of urban land, as well as 15.6 km2 of agricultural land, including 9.5 km2 of olive groves and 5.2 km2 of vineyards and fruit/nut orchards.
    Description: Published
    Description: 1001-1027
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: reserved
    Keywords: Lava flow ; Risk ; FLOWGO ; ASTER image ; Land classification ; Mt. Etna ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 44
    Publication Date: 2017-04-04
    Description: This paper describes the analyses of the single-station ambient-vibration measurements performed on the Italian accelerometric network to detect site resonance phenomena potentially affecting earthquake recordings. The use of low cost, high quality microtremor measurement can be helpful to discriminate among soil classes, since several classification schemes based on resonance frequencies were proposed in the last decades. Operatively, in the framework of the Italian Strong Motion Database project (DPC-INGV 2007–2009 S4; http://esse4.mi.ingv.it), soil resonance frequencies have been evaluated from more than 200 ambient vibration measurements in correspondence of accelerometric stations included in ITACA (http://itaca.mi.ingv.it/ItacaNet/). The noise recordings have been analyzed using the same numerical protocol in order to standardize the results. Particular attention has been paid to evaluate the quality of measurements and to develop an on-purpose mathematical tool to automatically estimate the peaks in the horizontal-to-vertical spectral ratio (HVSR) curve. The reliability of the resonance frequencies from HVSR has been tested by comparing estimates provided by independent methods (modeling or earthquake recordings). The test confirmed the reliability of the microtremor HVSR for assessing the resonance frequencies of the examined sites.
    Description: Published
    Description: 1821-1838
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: Ambient vibration measurements ; Strong motion database ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 45
    Publication Date: 2017-04-03
    Description: Among the eruptive styles, the Strombolian activity is one of the more easy to study because of its repetitive behavior. For this reason large amount of data can be comfortably collected. Strombolian volcanoes are like natural laborato- ries repeating the same experiment (individual explosions) many times each day. The development of quantitative models of eruptive dynamics is driven by the comparison of experimental ob- servations and synthetic data obtained through mathemat- ical, numerical or analogue modeling. Since Strombolian activity offers a profuse amount of interesting seismic signals, during the last decades there has been growing attention on seismological techniques aimed at retrieving the conduit geometry and the eruption dynamics from the seismological recordings. One of these techniques, the source function inversion, is able to re- trieve a summary of the forces acting on the volcanic con- duit during the VLP event generation [5]. The comparison of observed source functions with synthetic ones, obtained through numerical modeling, allow us to put constraints on the proposed models. Quantitative models, able to fit seismological observa- tions, are a powerful tool for interpreting seismic record- ings and therefor the seismological monitoring of active volcanoes.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: restricted
    Keywords: Strombolian activity ; Slug flow ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 46
    Publication Date: 2017-04-04
    Description: Seismic activity, ground deformation, and soil and fumarole temperatures acquired during 2004–2007 at Vulcano (Aeolian Islands) are analysed and the time relations among the different time series are discussed. Changes in temperature of fumarolic gases took place during four ‘‘anomalous’’ periods (November 2004–March 2005; October 2005–February 2006; August–October 2006; July–December 2007) at the same time as an increasing number of volcano-seismic events. In particular, the temperatures at high temperature vents and at steam heated soil ranged in time from 180 to 440 C and from 20 to 90 C, respectively. The maximum daily number of volcano-seismic events was 57, reached during the second anomalous period. This seismicity, characterised by focal depth generally lower than 1 km below sea level (b.s.l.) and composed of different kinds of events associated to both resonance and shear failure processes, is related to the shallow dynamics of the hydrothermal system. During the analysed period, very few volcano-tectonic earthquakes took place and tilt recordings showed no sharp or important changes. In light of such observations, the increases in both temperature and volcano-seismic events number were associated to increases in the release of gas from a deep and stable magma body, without magma intrusions within the shallow hydrothermal system. Indeed, a greater release of gas from depth leads to increased fluid circulation, that can promote increases in volcano-seismic events number by both fracturing processes and resonance and vibration in cracks and conduits. The different trends observed in the measured geochemical and geophysical series during the anomalous periods can be due to either time changes in the medium permeability or a changing speed of gas release from a deep magma body. Finally, all the observed variations, together with the changing temporal distribution of the different seismic event kinds, suggest that the hydrothermal system at Vulcano can be considered unsteady and dynamic.
    Description: Published
    Description: 167–182
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismolog ; soil and fumarole temperatures ; tilt data ; hydrothermal system ; Vulcano Island ; volcanic unrest ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 47
    Publication Date: 2017-04-03
    Description: The Salina, Lipari, and Vulcano volcanic ridge and the surrounding sea sectors (Aeolian Archipelago, Southern Tyrrhenian Sea, Italy) are characterized by vents responsible for a recent (〈40 ka—1889/1890 AD) effusive and explosive subareal activity and repeated, 56 to 7 ka in age, submarine explosive eruptions from source areas located between Lipari and Vulcano. A spectral depth estimation of the magnetic bottom using a fractal method on aeromagnetic data from Vulcano, Lipari, and Salina volcanic ridge allows us to constrain the Curie isotherm depth. The elevated portion of the isotherm is between 2 and 3 km below Salina and Vulcano and about 1 km below Lipari. The Curie depth results in the context of other geological and geophysical evidence suggest that the rise of the Curie isotherm is mainly due to the occurrence of shallow heat sources such as magma ponds and associated hydrothermal systems. The short-wavelength magnetic anomaly field reflects magnetic contrasts from highly magnetized volcanic bodies, low-magnetization sediments, and hydrothermally altered rocks. Borehole temperature data verify the Curie temperature derived from the magnetic methods on the island of Vulcano.We conclude that the whole Vulcano, Lipari, and Salina volcanic ridge is active and should be monitored.
    Description: INGV
    Description: Published
    Description: article 710
    Description: 1.10. TTC - Telerilevamento
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 3.4. Geomagnetismo
    Description: 3.6. Fisica del vulcanismo
    Description: 5.4. Banche dati di geomagnetismo, aeronomia, clima e ambiente
    Description: JCR Journal
    Description: restricted
    Keywords: Magnetic spectral depths ; Curie temperature ; volcanism ; Aeolian Islands ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.03. Heat generation and transport ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
    Publication Date: 2018-03-21
    Description: Among surface waters, lakes in volcanic areas display the greatest range in pH values (from negative values up to about 12). The present chapter will be a short review of the main features of alkaline lakes, which belong to the high-pH part of this range. They are characterised by saline or hypersaline waters, pH values higher than 9 and high Na+, HCO3- and CO32- and low Ca2+ concentrations. Alkaline lakes are found in quiescent or recently extinct volcanic areas where neither water vapour nor acidic magmatic gases can reach surface waters. Their occurrence depends on peculiar climatic and geologic conditions that allow evaporative concentration of the water (potentially, evaporation much higher than water inputs and endorheic basins) and on geochemical factors that favour a chemical evolution towards an alkaline environment (composition of the dilute input waters characterised by a ratio between total dissolved inorganic carbon and earth-alkaline elements much higher than 1). Such initial composition, due to evaporative concentration, after the deposition of earth-alkaline carbonate minerals, will lead to the above-mentioned typical composition. Alkaline lakes also host microbial communities sometimes characterised by extremely high productivity. These microbial communities are scientifically remarkable because they comprise some interesting extremophiles, which can grow not only at very high pH and salinity conditions but also in the presence of elevated concentrations of toxic elements (e.g. As, Se, Te).
    Description: Submitted
    Description: 4.4. Scenari e mitigazione del rischio ambientale
    Description: reserved
    Keywords: volcanic lake, soda lake, alkaline lake ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 49
    Publication Date: 2019-12-09
    Description: . In this work we analysed the time series of daily solutions of 4 Italian GPS permanent stations with the aim of investigating the presence of temporal correlations and their impact on the estimation of weekly solution and velocity field precisions. We found that precisions are remarkably lower when temporal correlations are considered; in particular, the mean horizontal precisions of weekly solutions are up to 5 times lower and the horizontal velocity precisions are about 1.5-2 times lower. This topic has 2 relevant applications: the assessment of the quality of a reference system maintenance by GPS permanent stations and the coordinate differences significance test for geodynamical applications.
    Description: Published
    Description: 1.9. Rete GPS nazionale
    Description: N/A or not JCR
    Description: restricted
    Keywords: GPS permanent network,temporal correlations, autocovariance functions ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.08. Theory and Models
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  • 50
    Publication Date: 2020-02-24
    Description: A multidisciplinary geological and compositional investigation allowed us to reconstruct the occurrence of flank eruptions on the lower NE flank of Stromboli volcano since 15 ka. The oldest flank eruption recognised is Roisa, which occurred at ~15 ka during the Vancori period, and has transitional compositional characteristics between the Vancori and Neostromboli phases. Roisa was followed by the San Vincenzo eruption that took place at ~12 ka during the early stage of Neostromboli period. The eruptive fissure of San Vincenzo gave rise to a large scoria cone located below the village of Stromboli, and generated a lava flow, most of which lies below sea level. Most of the flank eruptions outside the barren Sciara del Fuoco occurred in a short time, between ~9 and 7 ka during the Neostromboli period, when six eruptive events produced scoria cones, spatter ramparts and lava flows. The Neostromboli products belong to a potassic series (KS), and cluster in two differently evolved groups. After an eruptive pause of ~5,000 years, the most recent flank eruption involving the NE sector of the island occurred during the Recent Stromboli period with the formation of the large, highly K calc-alkaline lava flow field, named San Bartolo. The trend of eruptive fissures since 15 ka ranges from N30°E to N55°E, and corresponds to the magma intrusions radiating from the main feeding system of the volcano.
    Description: The mapping of Stromboli was supported by a grant to S. Calvari (Project V2/01, 2005–2007, funded by the Istituto Nazionale di Geofisica e Vulcanologia and by the Italian Civil Protection). This work was partly supported by INGV through a research grant financed by MIUR-FIRB to G. Norini. We wish to thank the former Director of INGV-Sezione di Catania, A. Bonaccorso, for making additional funds available for field trip and datings.
    Description: In press
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: restricted
    Keywords: Stromboli ; flank fissures ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 51
    Publication Date: 2020-02-24
    Description: A simulation and two reanalyses from 1985 to 2007 have been produced for the Mediterranean Sea using different assimilation schemes: a reduced-order optimal interpolation [System for Ocean Forecast and Analysis (SOFA)] and a three-dimensional variational scheme (OceanVar). The observational dataset consists of vertical temperature and salinity in situ profiles and along-track satellite sea level anomalies; daily mean fields of satellite sea surface temperature are used for correcting the air–sea fluxes. This paper assesses the quality of the reanalyses with respect to observations and the simulation. Both the SOFA and OceanVar schemes give very similar root-mean-square errors and biases for temperature and salinity fields compared with the assimilated observations. The largest errors are at the thermocline level and in regions of large eddy field variability. However, OceanVar gives 20% better results for sea level anomaly root-mean-square error.
    Description: Published
    Description: 569-59
    Description: JCR Journal
    Description: open
    Keywords: Mediterranean Sea ; 03. Hydrosphere::03.01. General::03.01.05. Operational oceanography
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  • 52
    Publication Date: 2020-02-24
    Description: We investigated the relationship between volcano-seismic events, recorded at La Fossa crater of Vulcano (Aeolian Islands, Italy) during 2004-2006, and the dynamics of the hydrothermal system. During the period of study, three episodes of increasing numbers of volcano-seismic events took place at the same time as geothermal and geochemical anomalies were observed. These geothermal and geochemical anomalies have been interpreted as resulting from an increasing deep magmatic component of the hydrothermal fluids. Three classes of seismic events (long period, high frequency and monochromatic events), characterised by different spectral content and various similarity of the waveforms, have been recognised. These events, clustered mainly below La Fossa crater area at depths of 0.5–1.1 km b.s.l., were space-distributed according to the classes. Based on their features, we can infer that such events at Vulcano are related to two different source mechanisms: (1) fracturing processes of rocks and (2) resonance of cracks (or conduits) filled with hydrothermal fluid. In the light of these source mechanisms, the increase in the number of events, at the same time as geochemical and geothermal anomalies were observed, was interpreted as the result of an increasing magmatic component of the hydrothermal fluids, implying an increase of their flux. Indeed, such variation caused an increase of both the pore pressure within the rocks of the volcanic system and the amount of ascending fluids. Increased pore pressures gave rise to fracturing processes, while the increased fluid flux favoured resonance and vibration processes in cracks and conduits. Finally, a gradual temporal variation of the waveform of the hybrid events (one of the subclasses of long period events) was observed, likely caused by heating and drying of the hydrothermal system.
    Description: Published
    Description: 803-816
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismology ; Vulcano Island ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
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  • 53
    Publication Date: 2020-02-24
    Description: In this paper we present a model for the growth of a maar-diatreme complex in a shallow marine environment. The Miocene-age Costa Giardini diatreme near Sortino, in the region of the Iblei Mountains of southern Sicily, has an outer tuff ring formed by the accumulation of debris flows and surge deposits during hydromagmatic eruptions. Vesicular lava clasts, accretionary lapilli and bombs in the older ejecta indicate that initial eruptions were of gas-rich magma. Abundant xenoliths in the upper, late-deposited beds of the ring suggest rapid magma ascent, and deepening of the eruptive vent is shown by the change in slope of the country rock. The interior of the diatreme contains nonbedded breccia composed of both volcanic and country rock clasts of variable size and amount. The occurrence of bedded hyaloclastite breccia in an isolated outcrop in the middle-lower part of the diatreme suggests subaqueous effusion at a low rate following the end of explosive activity. Intrusions of nonvesicular magma, forming plugs and dikes, occur on the western side of the diatreme, and at the margins, close to the contact between breccia deposits and country rock; they indicate involvement of volatile-poor magma, possibly during late stages of activity. We propose that initial hydromagmatic explosive activity occurred in a shallow marine environment and the ejecta created a rampart that isolated for a short time the inner crater from the surrounding marine environment. This allowed explosive activity to draw down the water table in the vicinity of the vent and caused deepening of the explosive center. A subsequent decrease in the effusion rate and cessation of explosive eruptions allowed the crater to refill with water, at which time the hyaloclastite was deposited. Emplacement of dikes and plugs occurred nonexplosively while the breccia sediment was mostly still soft and unconsolidated, locally forming peperites. The sheltered, low-energy lagoon filled with marine limestones mixed with volcaniclastic material eroded from the surrounding ramparts. Ultimately, lagoonal sediments accumulated in the crater until subsidence or erosion of the tuff ring caused a return to normal shallow marine conditions.
    Description: In press
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: open
    Keywords: maar ; diatreme ; volcaniclastic ; hyaloclastite ; Iblean plateau ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 54
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    In:  EPIC3Monthly Weather Review., American Meteorological Society, 140(5), pp. 1589-1602
    Publication Date: 2014-04-17
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  • 55
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
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  • 56
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    In:  EPIC3Polar Biology, Springer, 35(7), pp. 1003-1012, ISSN: 0722-4060
    Publication Date: 2019-07-16
    Description: The Antarctic krill, Euphausia superba, and the Northern krill, Meganyctiphanes norvegica, are closely related species but occupy significantly different trophic and climatic environments. E. superba holds a key position as a phytoplankton grazer in the Southern Ocean. The omnivorous M. norvegica is an important member of plankton communities in the Northeast Atlantic. Both species expressed high proteolytic activities which were dominated by serine proteinases. In the stomachs of Antarctic krill, activities of total proteinase, trypsin, and chymotrypsin were significantly higher than in Northern krill. In the midgut glands, however, total proteinase and trypsin activities were similar in both species, but chymotrypsin activity was significantly higher in Antarctic krill. Moreover, Antarctic krill expressed four trypsin isoforms while only one isoform appeared in Northern krill. Chymotrypsin was present in either species as one single isoform. Antarctic krill adapted to the low and patchy distribution of food by elevated enzyme activities and the expression of trypsin isoforms with slightly different catalytic properties. Presumably, these enzymes facilitate in concerted action the efficient utilization of proteins from phytoplankton, the major food. Northern krill, in contrast, seems not to be equipped to face food limitation. It expresses a “simple” or “basic” set of digestive enzymes for utilizing abundant and easily digestible prey.
    Repository Name: EPIC Alfred Wegener Institut
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  • 57
    Publication Date: 2019-07-17
    Description: The atmospheric general circulation model EC-EARTH-IFS has been applied to investigate the influence of both a reduced and a removed Arctic sea ice cover on the Arctic energy budget and on the climate of the Northern mid-latitudes. Three 40-year simulations driven by original and modified ERA-40 sea surface temperatures and sea ice concentrations have been performed at T255L62 resolution, corresponding to 79 km horizontal resolution. Simulated changes between sensitivity and reference experiments are most pronounced over the Arctic itself where the reduced or removed sea ice leads to strongly increased upward heat and longwave radiation fluxes and precipitation in winter. In summer, the most pronounced change is the stronger absorption of shortwave radiation which is enhanced by optically thinner clouds. Averaged over the year and over the area north of 70° N, the negative energy imbalance at the top of the atmosphere decreases by about 10 W/m2 in both sensitivity experiments. The energy transport across 70° N is reduced. Changes are not restricted to the Arctic. Less extreme cold events and less precipitation are simulated in sub-Arctic and Northern mid-latitude regions in winter.
    Repository Name: EPIC Alfred Wegener Institut
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  • 58
    Publication Date: 2020-02-10
    Description: Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19–45 Pg C by 2040, 162–288 Pg C by 2100, and 381–616 Pg C by 2300 in CO2 equivalent using 100-year CH4 global warming potential (GWP). These values become 50 % larger using 20-year CH4 GWP, with a third to a half of expected climate forcing coming from CH4 even though CH4 was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing.
    Repository Name: EPIC Alfred Wegener Institut
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  • 59
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
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  • 60
    Publication Date: 2019-07-16
    Description: Copepods can be associated with different kinds and different numbers of bacteria. This was already shown in the past with culture-dependent microbial methods or microscopy and more recently by using molecular tools. In our present study, we investigated the bacterial community of four frequently occurring copepod species, Acartia sp., Temora longicornis, Centropages sp. and Calanus helgolandicus from Helgoland Roads (North Sea) over a period of two years using DGGE (denaturing gradient gel electrophoresis) and subsequent sequencing of 16S-rDNA fragments. To complement the PCR-DGGE analyses, clone libraries of copepod samples from June 2007 and 208 were generated. Based on the DGGE banding patterns of the two years survey, we found no significant differences between the communities of distinct copepod species, nor did we find any seasonality. Overall, we identified 67 phylotypes (〉 97% similarity) falling into the bacterial phyla of Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. The most abundant phylotypes were affiliated to the Alphaproteobacteria. In comparison of PCR-DGGE and clone libraries, phylotypes of the Gammaproteobacteria dominated the clone libraries, whereas Alphaproteobacteria were most abundant in the PCR-DGGE analyses
    Repository Name: EPIC Alfred Wegener Institut
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  • 61
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    In:  EPIC3Biodiversität und Klimawandel: Auswirkungen und Handlungsoptionen für den Naturschutz in Mitteleuropa, Springer, pp. 217-222, ISSN: ISBN 978-3-642-29691-8
    Publication Date: 2018-02-16
    Repository Name: EPIC Alfred Wegener Institut
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  • 62
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    In:  EPIC3Geo-Marine Letters, Springer, 33(5), pp. 381-390, ISSN: 1432-1157
    Publication Date: 2019-07-16
    Description: Sediment thickness was evaluated on the western flank of the East Pacific Rise (EPR) at 45°S, based on high-resolution seismic data gathered during cruise 213/2 of R/V Sonne in 2011. Two zones with distinctly different sediment thickness were identified, separated by a transitional zone bordering a pseudo-fault. Sediment in the more distal zone 2 is almost twice as thick (~120 m) as in zone 1 close to the EPR. This is in contrast to the expected sedimentary column thickening with seafloor age and distance from the spreading axis. The younger of two seismic units detected within the sedimentary column (EPR-2) occurs mainly in the distal zone on crust older than 9 Ma, whereas on younger crust it is present only in small isolated bodies. Both sedimentary units drape the basement. The drape is interpreted to represent particle settling from suspension and a generally low regional primary productivity. The spatial variation in sediment thickness cannot be explained by existing models, and other processes considered in the present case are (1) higher productivity in the western sector of the survey area, where thicker sediments were observed (zone 2), (2) the formation of sediment drifts near basement highs (‘seamount effect’), due to flow of Lower Circumpolar Deep Water affecting sediment deposition, and (3) erosion and/or non-deposition of the younger EPR-2 unit, due to elevated bed shear stresses associated with eddies transferring kinetic energy to the seafloor
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  • 63
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    In:  EPIC3Earth System Science: Bridging the Gaps between Disciplines Perspectives from a Multi-disciplinary Helmholtz Research School, Heidelbert, Springer, 138 p., pp. 57-64, ISBN: ISBN 978-3-642-32234
    Publication Date: 2019-08-16
    Repository Name: EPIC Alfred Wegener Institut
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  • 64
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    In:  EPIC3Earth System Science: Bridging the Gaps between Disciplines Perspectives from a Multi-disciplinary Helmholtz Research School, Heidelberg, Springer, 138 p., pp. 64-69, ISBN: ISBN 978-3-642-32234
    Publication Date: 2014-04-15
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  • 65
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    In:  EPIC3Earth System Science: Bridging the Gaps between Disciplines Perspectives from a Multi-disciplinary Helmholtz Research School, Heidelberg, Springer, 138 p., pp. 74-79, ISBN: ISBN 978-3-642-32234
    Publication Date: 2014-04-15
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  • 66
    Publication Date: 2021-07-19
    Description: The summer water balance of a typical Siberian polygonal tundra catchment is investigated in order to identify the spatial and temporal dynamics of its main hydrological processes. The results show that, besides precipitation and evapotranspiration, lateral flow considerably influences the site-specific hydrological conditions. The prominent microtopography of the polygonal tundra strongly controls lateral flow and storage behaviour of the investigated catchment. Intact rims of low-centred polygons build hydrological barriers, which release storage water later in summer than polygons with degraded rims and troughs above degraded ice wedges. The barrier function of rims is strongly controlled by soil thaw, which opens new subsurface flow paths and increases subsurface hydrological connectivity. Therefore, soil thaw dynamics determine the magnitude and timing of subsurface outflow and the redistribution of storage within the catchment. Hydraulic conductivities in the elevated polygonal rims sharply decrease with the transition from organic to mineral layers. This interface causes a rapid shallow subsurface drainage of rainwater towards the depressed polygon centres and troughs. The re-release of storage water from the centres through deeper and less conductive layers helps maintain a high water table in the surface drainage network of troughs throughout the summer.
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  • 67
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    In:  EPIC3The Mediterranean Sea: Its history and present challenges, The Mediterranean Sea: Its hisory and present challenges, Springer, pp. 499-504
    Publication Date: 2016-02-13
    Repository Name: EPIC Alfred Wegener Institut
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  • 68
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    In:  EPIC3Journal of Geodesy, Springer, ISSN: 0949-7714
    Publication Date: 2021-07-19
    Description: Our study analyses satellite and land-based observations of the Yakutsk region centred at the Lena watershed, an area characterised mainly by continuous permafrost. Using monthly solutions of the Gravity Recovery And Climate Experiment satellite mission, we detect amass increase over central Siberia from 2002 to 2007 which reverses into a mass decrease between 2007 and 2011. No significant mass trend is visible for the whole observation period. To further quantify this behaviour, different mass signal components are studied in detail: (1) inter-annual variation in the atmospheric mass, (2) a possible effect of glacial isostatic adjustment (GIA), and (3) hydrological mass variations. In standard processing the atmospheric mass signal is reduced based on the data from numerical weather prediction models. We use surface pressure observations in order to validate this atmospheric reduction. On inter-annual time scale the difference between the atmospheric mass signal from model prediction and from surface pressure observation is 〈4mm in equivalentwater height. The effect of GIA on the mass signal over Siberia is calculated using a global ice model and a spherically symmetric, compressible, Maxwell-viscoelastic earth model. The calculation shows that for the investigated area any effect of GIA can be ruled out. Hence, the main part of the signal can be attributed to hydrological mass varia-tions. We briefly discuss potential hydrological effects such as changes in precipitation, river discharge, surface and subsurface water storage.
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  • 69
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    In:  EPIC3Modelling and Management of Engineering Processes, Modelling and Management of Engineering Processes, London, Springer, pp. 53-64, ISBN: 978-1-84996-198-1
    Publication Date: 2014-04-15
    Description: What is the impact of new design methodologies and methods on the industrial product development process and its productivity? This is one of the key questions for today's industrial engineering companies when they decide on the introduction of new methods or tools, as well as for researchers and tool providers when they assess their ideas and work. A quantitative (at best monetary) assessment of a new design method's value and impact will increase a manager's decision basis significantly and will lead to well directed investments in process optimisations. It is not sufficient to analyse the impact of a new design method just for the specific process step it is applied to. Implications on following steps, sometimes on the whole engineering process must be considered as well. Furthermore, decisions on the use of new design methods must be made on a multi-criteria basis through the well-known cost/time/quality triangle (e.g. Burghardt, 2006).
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  • 70
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    In:  EPIC3Coastal and Marine Geospatial Technologies, Coastal Systems and Continental Margins, Springer, 451 p., pp. 187-196
    Publication Date: 2016-07-11
    Repository Name: EPIC Alfred Wegener Institut
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  • 71
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    In:  EPIC3Earth System Science: Bridging the Gaps between Disciplines Perspectives from a Multi-disciplinary Helmholtz Research School, Heidelberg, Springer, 138 p., pp. 70-74, ISBN: ISBN 978-3-642-32234
    Publication Date: 2014-04-15
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  • 72
    Publication Date: 2019-07-16
    Description: In contemporary ocean science, modeling systems that integrate understanding of complex multiscale phenomena and utilize efficient numerics are paramount. Many of today's fundamental ocean science questions involve multiple scales and multiple dynamics. A new generation of modeling systems would allow to study such questions quantitatively by being less restrictive dynamically and more efficient numerically than more traditional systems.
    Repository Name: EPIC Alfred Wegener Institut
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  • 73
    Publication Date: 2019-07-17
    Description: Der Klimawandel, die Globalisierung der Märkte, der demografische Wandel, die rasanten technologischen Entwicklungen sowie die Veränderungen der Landnutzung sind verschiedene Facetten des sogenannten Globalen Wandels. Welchen Einfluss der Globale Wandel auf die verfügbaren Wasserressourcen hat, ist von Region zu Region unterschiedlich. In jedem Fall steigt der Nutzungsdruck auf die Georessource Wasser weiter an; bereits jetzt zeichnen sich regionale Konkurrenzen und Konflikte bei der Nutzung ab. So wird sich beispielsweise der Bewässerungsbedarf der Landwirtschaft durch die steigende globale Nachfrage nach Nahrungsmitteln und Rohstoffen weiter erhöhen. Infolge des Globalen Wandels und der Veränderungen der Flusslandschaften ist auch vermehrt mit Hochwasserereignissen zu rechnen. Ausreichende Wasserressourcen in hinreichender Qualität zu sichern, sowie der Gewässerschutz und die Hochwasservorsorge sind daher zentrale Anliegen unserer Gesellschaft. Innovative Anpassungsstrategien und neue Technologien können hierbei nicht nur zu einer nachhaltigen Wasser- und Bodenbewirtschaftung führen, sondern gleichzeitig auch wirtschaftliche Chancen auf dem Weltmarkt eröffnen. Gerade durch die Entwicklung und den Export von Technologien und Verfahrensweisen kann Deutschland einen Beitrag zur Lösung globaler Wasserprobleme leisten.
    Repository Name: EPIC Alfred Wegener Institut
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  • 74
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
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  • 75
    Publication Date: 2019-07-16
    Description: In this experimental study, we compared the embryonic respiration rate in air and water of six East African sesarmid species with intertidal, supratidal and arboreal habits, to highlight possible adaptations in embryonic metabolism to their different lifestyles. The embryos of all analysed crabs showed bimodal respiration, but we did not find a trend towards an enhanced embryonic oxygen uptake in air from the intertidal to the arboreal and supratidal species. However, the late-stage embryos of the most land-adapted species, Chiromantes spp., showed an enhanced metabolism when immersed in sea water that we interpreted as an adaptive recovery mechanism to cope with the storage of by-products due to marine-based metabolic pathways during long emersion periods. Thus, we showed that the embryos of land-adapted species, although still strongly water dependent, are well adapted to semi-terrestrial habitats and represent a minor limiting factor for females, which are not restricted in their emersion period by the oxygen requirements of their embryos.
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  • 76
    Publication Date: 2017-06-05
    Description: The endemic Antarctic brown macroalga Desmarestia anceps colonizes the subtidal between 5 and 30 m in Potter Cove on King George Island (South Shetland Islands, Antarctica). Experiments were conducted to study photosynthetic activities, antioxidative enzymes and UV tolerance of field-grown individuals with respect to the light histories along different subtidal positions. Individuals collected from the upper (5.5 m) and mid-subtidal (9.0 m) are characterized by high maximum electron transport rates (ETRmax) measured by PAM-fluorometry and high activities of superoxide dismutase (SOD) supported by considerable activities of glutathione reductase. Individuals of this species from the upper subtidal are able to tolerate high irradiances of UV-B radiation because its photosynthetic apparatus is putatively well protected by phlorotannins. In contrast, individuals from lower subtidal positions (13.5 and 15.5 m) showed an opposite trend: lower ETRmax and SOD activities as well as a lower UV tolerance of photosynthesis. Moreover, a non-denaturing polyacrylamide gel electrophoresis (native PAGE) of a partially purified crude extract reveals that D. anceps has probably six isoforms of SOD. These intra-specific patterns imply a high phenotypical plasticity of D. anceps with respect to its photosynthesis and photoprotective mechanisms. Overall, photosynthesis, UV tolerance and antioxidative potential are highly regulated in D. anceps corresponding to the respective light regimes along its natural growth sites.
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  • 77
    Publication Date: 2022-05-25
    Description: © The Authors, 2009. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License. The definitive version was published in Estuaries and Coasts 33 (2010): 15-29, doi:10.1007/s12237-009-9244-y.
    Description: Future estuarine geomorphic change, in response to climate change, sea-level rise, and watershed sediment supply, may govern ecological function, navigation, and water quality. We estimated geomorphic changes in Suisun Bay, CA, under four scenarios using a tidal-timescale hydrodynamic/sediment transport model. Computational expense and data needs were reduced using the morphological hydrograph concept and the morphological acceleration factor. The four scenarios included (1) present-day conditions; (2) sea-level rise and freshwater flow changes of 2030; (3) sea-level rise and decreased watershed sediment supply of 2030; and (4) sea-level rise, freshwater flow changes, and decreased watershed sediment supply of 2030. Sea-level rise increased water levels thereby reducing wave-induced bottom shear stress and sediment redistribution during the wind-wave season. Decreased watershed sediment supply reduced net deposition within the estuary, while minor changes in freshwater flow timing and magnitude induced the smallest overall effect. In all future scenarios, net deposition in the entire estuary and in the shallowest areas did not keep pace with sea-level rise, suggesting that intertidal and wetland areas may struggle to maintain elevation. Tidal-timescale simulations using future conditions were also used to infer changes in optical depth: though sea-level rise acts to decrease mean light irradiance, decreased suspended-sediment concentrations increase irradiance, yielding small changes in optical depth. The modeling results also assisted with the development of a dimensionless estuarine geomorphic number representing the ratio of potential sediment import forces to sediment export forces; we found the number to be linearly related to relative geomorphic change in Suisun Bay. The methods implemented here are widely applicable to evaluating future scenarios of estuarine change over decadal timescales.
    Description: This study was supported by the US Geological Survey’s Priority Ecosystems Science program, CALFED Bay/ Delta Program, and the University of California Center for Water Resources.
    Keywords: Numerical modeling ; Geomorphology ; Scenarios ; Sediment transport
    Repository Name: Woods Hole Open Access Server
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  • 78
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 40 (2010): 789-801, doi:10.1175/2009JPO4039.1.
    Description: The issue of internal wave–mesoscale eddy interactions is revisited. Previous observational work identified the mesoscale eddy field as a possible source of internal wave energy. Characterization of the coupling as a viscous process provides a smaller horizontal transfer coefficient than previously obtained, with vh 50 m2 s−1 in contrast to νh 200–400 m2 s−1, and a vertical transfer coefficient bounded away from zero, with νυ + (f2/N2)Kh 2.5 ± 0.3 × 10−3 m2 s−1 in contrast to νυ + (f2/N2)Kh = 0 ± 2 × 10−2 m2 s−1. Current meter data from the Local Dynamics Experiment of the PolyMode field program indicate mesoscale eddy–internal wave coupling through horizontal interactions (i) is a significant sink of eddy energy and (ii) plays an O(1) role in the energy budget of the internal wave field.
    Keywords: Eddies ; Internal waves ; Mesoscale processes
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  • 79
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 40 (2010): 934-948, doi:10.1175/2009JPO4214.1.
    Description: The mean heat and salt balances over the Middle Atlantic Bight continental shelf are investigated by testing the hypothesis that surface fluxes of heat or freshwater are balanced by along-isobath fluxes resulting from the mean, depth-averaged, along-isobath flow acting on the mean, depth-averaged, along-isobath temperature or salinity gradient. This hypothesized balance is equivalent in a Lagrangian frame to a column of water, for example, warming because of surface heating as it is advected southward along isobath by the mean flow. Mean depth-averaged temperatures increase from north to south along isobath at a rate of 2°C (1000 km)−1 at midshelf, which is consistent with the hypothesized balance and mean surface heat flux estimates from the 50-yr NCEP Reanalysis. However, mean surface heat flux estimates from the higher-resolution 20-yr Objectively Analyzed Air–Sea Fluxes (OAFlux) reanalysis are too small to balance the along-isobath heat flux divergence implying a cross-shelf heat flux convergence. It is unclear which surface heat flux estimate, NCEP or OAFlux, is more accurate. The cross-shelf heat flux convergence resulting from the mean cross-shelf circulation is too small to balance the along-isobath heat flux divergence. Mean depth-averaged salinities increase from north to south along isobath at a rate of 1 (psu) (1000 km)−1 at midshelf. Mean precipitation and evaporation rates nearly balance so that the net freshwater flux is too small by more than an order of magnitude to account for the observed along-isobath increase in salinity. The cross-shelf salt flux divergence resulting from the mean cross-shelf circulation has the wrong sign to balance the divergence in the along-isobath salt flux. These results imply there must be an onshore “eddy” salt flux resulting from the time-dependent current and salinity variability. The along-isobath temperature and salinity gradients compensate for each other so that the mean, depth-averaged, along-isobath density gradient is approximately zero. This suggests that there may be a feedback between the along-isobath density gradient and the onshore salt and heat fluxes that maintains the density gradient near zero.
    Description: This work was funded by the National Science Foundation under Grants OCE-0220773, OCE-0241292, andOCE-0548961.
    Keywords: Continental shelf/slope ; Atlantic Ocean ; Fluxes
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  • 80
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2010. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 40 (2010): 1075-1086, doi:10.1175/2009JPO4375.1.
    Description: A quasigeostrophic, two-layer model is used to study the baroclinic circulation around a thin, meridionally elongated island. The flow is driven by either buoyancy forcing or wind stress, each of whose structure would produce an antisymmetric double-gyre flow. The ocean bottom is flat. When the island partially straddles the intergyre boundary, fluid from one gyre is forced to flow into the other. The amount of the intergyre flow depends on the island constant, that is, the value of the geostrophic streamfunction on the island in each layer. That constant is calculated in a manner similar to earlier studies and is determined by the average, along the meridional length of the island, of the interior Sverdrup solution just to the east of the island. Explicit solutions are given for both buoyancy and wind-driven flows. The presence of an island of nonzero width requires the determination of the baroclinic streamfunction on the basin’s eastern boundary. The value of the boundary term is proportional to the island’s area. This adds a generally small additional baroclinic intergyre flow. In all cases, the intergyre flow produced by the island is not related to topographic steering of the flow but rather the pressure anomaly on the island as manifested by the barotropic and baroclinic island constants. The vertical structure of the flow around the island is a function of the parameterization of the vertical mixing in the problem and, in particular, the degree to which long baroclinic Rossby waves can traverse the basin before becoming thermally damped.
    Description: This research was supported in part by NSF Grant OCE 0451086.
    Keywords: Gyres ; Baroclinic flows ; Topographic effects ; Streamfunction ; Orographic effects
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  • 81
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    Unknown
    American Meteorological Society
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 2910-2925, doi:10.1175/2009JPO4139.1.
    Description: The propagation of Rossby waves on a midlatitude β plane is investigated in the presence of density diffusion with the aid of linear hydrostatic theory. The search for wave solutions in a vertically bounded medium subject to horizontal (vertical) diffusion leads to an eigenvalue problem of second (fourth) order. Exact solutions of the problem are obtained for uniform background stratification (N), and approximate solutions are constructed for variable N using the Wentzel–Kramers–Brillouin method. Roots of the eigenvalue relations for free waves are found and discussed. The barotropic wave of adiabatic theory is also a solution of the eigenvalue problem as this is augmented with density diffusion in the horizontal or vertical direction. The barotropic wave is undamped as fluid parcels in the wave move only horizontally and are therefore insensitive to the vortex stretching induced by mixing. On the other hand, density diffusion modifies the properties of baroclinic waves of adiabatic theory. In the presence of horizontal diffusion the baroclinic modes are damped but their vertical structure remains unaltered. The ability of horizontal diffusion to damp baroclinic waves stems from its tendency to counteract the deformation of isopycnal surfaces caused by the passage of these waves. The damping rate increases (i) linearly with horizontal diffusivity and (ii) nonlinearly with horizontal wavenumber and mode number. In the presence of vertical diffusion the baroclinic waves suffer both damping and a change in vertical structure. In the long-wave limit the damping is critical (wave decay rate numerically equal to wave frequency) and increases as the square roots of vertical diffusivity and zonal wavenumber. Density diffusion in the horizontal or vertical direction reduces the amplitude of the phase speed of westward-propagating waves. Observational estimates of eddy diffusivities suggest that horizontal and vertical mixing strongly attenuates baroclinic waves in the ocean but that vertical mixing is too weak to notably modify the vertical structure of the gravest modes.
    Description: This work was supported by the U.S. National Science Foundation.
    Keywords: Rossby waves ; Extratropics ; Buoyancy ; Mixing
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  • 82
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 1541-1550, doi:10.1175/2008JPO3999.1.
    Description: The response of a zonal channel to a uniform, switched-on but subsequently steady poleward outflow is presented. An eastward coastal current with a Kelvin wave’s cross-shore structure is found to be generated instantly upon initiation of the outflow. The current is essentially in geostrophic balance everywhere except for the vicinity of the outflow channel mouth, where the streamlines must cross planetary vorticity contours to feed the current. The adjustment of this region generates a plume that propagates westward at Rossby wave speeds. The cross-shore structure of the plume varies with longitude, and at any given longitude it evolves with time. The authors show that the plume evolution can be understood both conceptually and quantitatively as the westward propagation of the Kelvin current’s meridional spectrum, with each spectral element propagating at its own Rossby wave group velocity.
    Description: This work was completed at Woods Hole Oceanographic Institution while T.S. Durland was supported by the Ocean and Climate Change Institute. M.A. Spall was supported by NSF Grant OCE-0423975, and J. Pedlosky by NSF Grant OCE-0451086. T.S. Durland acknowledges additional report preparation support from NASA Grant NNG05GN98G.
    Keywords: Coastal flows ; Estuaries ; Currents ; Vorticity ; Plumes
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  • 83
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Atmospheric and Oceanic Technology 25 (2008): 2091-2105, doi:10.1175/2008JTECHO587.1.
    Description: An automated, easily deployed Ice-Tethered Profiler (ITP) instrument system, developed for deployment on perennial sea ice in the polar oceans to measure changes in upper ocean water properties in all seasons, is described, and representative data from prototype instruments are presented. The ITP instrument consists of three components: a surface subsystem that sits atop an ice floe; a weighted, plastic-jacketed wire-rope tether of arbitrary length (up to 800 m) suspended from the surface element; and an instrumented underwater unit that employs a traction drive to profile up and down the wire tether. ITPs profile the water column at a programmed sampling interval; after each profile, the underwater unit transfers two files holding oceanographic and engineering data to the surface unit using an inductive modem and from the surface instrument to a shore-based data server using an Iridium transmitter. The surface instrument also accumulates battery voltage readings, buoy temperature data, and locations from a GPS receiver at a specified interval (usually every hour) and transmits those data daily. Oceanographic and engineering data are processed, displayed, and made available in near–real time (available online at http://www.whoi.edu/itp). Six ITPs were deployed in the Arctic Ocean between 2004 and 2006 in the Beaufort gyre with various programmed sampling schedules of two to six one-way traverses per day between 10- and 750–760-m depth, providing more than 5300 profiles in all seasons (as of July 2007). The acquired CTD profile data document interesting spatial variations in the major water masses of the Canada Basin, show the double-diffusive thermohaline staircase that lies above the warm, salty Atlantic layer, measure seasonal surface mixed layer deepening, and document several mesoscale eddies. Augmenting the systems already deployed and to replace expiring systems, an international array of more than one dozen ITPs will be deployed as part of the Arctic Observing Network during the International Polar Year (IPY) period (2007–08) holding promise for more valuable real-time upper ocean observations for operational needs, to support studies of ocean processes, and to facilitate numerical model initialization and validation.
    Description: Initial development of the ITP concept was supported by the Cecil H. and Ida M. Green Technology Innovation Program. Funding for construction and deployment of the prototype ITPs was provided by the National Science Foundation Oceanographic Technology and Interdisciplinary Coordination (OTIC) Program and Office of Polar Programs (OPP) under Grant OCE-0324233. Continued support has been provided by the OPP Arctic Sciences Section under Awards ARC-0519899 and ARC-0631951, and internal WHOI funding.
    Keywords: Profilers ; Sea ice ; Instrumentation/sensors ; Arctic
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  • 84
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1486–1500, doi:10.1175/2007JPO3767.1.
    Description: Fits of an annual harmonic to depth-average along-shelf current time series longer than 200 days from 27 sites over the Middle Atlantic Bight (MAB) continental shelf have amplitudes of a few centimeters per second. These seasonal variations are forced by seasonal variations in the wind stress and the cross-shelf density gradient. The component of wind stress that drives the along-shelf flow over most of the MAB mid- and outer shelf is oriented northeast–southwest, perpendicular to the major axis of the seasonal variation in the wind stress. Consequently, there is not a significant seasonal variation in the wind-driven along-shelf flow, except over the southern MAB shelf and the inner shelf of New England where the wind stress components forcing the along-shelf flow are north–south and east–west, respectively. The seasonal variation in the residual along-shelf flow, after removing the wind-driven component, has an amplitude of a few centimeters per second with maximum southwestward flow in spring onshore of the 60-m isobath and autumn offshore of the 60-m isobath. The spring maximum onshore of the 60-m isobath is consistent with the maximum river discharges in spring enhancing cross-shelf salinity gradients. The autumn maximum offshore of the 60-m isobath and a steady phase increase with water depth offshore of Cape Cod are both consistent with the seasonal variation in the cross-shelf temperature gradient associated with the development and destruction of a near-bottom pool of cold water over the mid and outer shelf (“cold pool”) due to seasonal variations in surface heat flux and wind stress.
    Description: This research was funded by the Ocean Sciences Division of the National Science Foundation under Grants OCE-820773, OCE-841292, and OCE- 848961.
    Keywords: Seasonal variability ; Ocean circulation ; Continental shelf ; Wind stress ; Density currents
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  • 85
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of The UK–SOLAS projects were funded by the Natural Environment Research Council Grants NE/C001826/1 (HiWASE), NE/C001842/1 (SEASAW), NE/C001702/1 (DOGEE), and NE/E011489/1 (DMS Fluxes); and by NSF Grants ATM05-26341 (Hawaii), OCE-0623450 (Miami), and NSF-OCE 0549887/0834340/0550000 (APL-UW). for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 90 (2009): 629-644, doi:10.1175/2008BAMS2578.1.
    Description: As part of the U.K. contribution to the international Surface Ocean–Lower Atmosphere Study, a series of three related projects—DOGEE, SEASAW, and HiWASE—undertook experimental studies of the processes controlling the physical exchange of gases and sea spray aerosol at the sea surface. The studies share a common goal: to reduce the high degree of uncertainty in current parameterization schemes. The wide variety of measurements made during the studies, which incorporated tracer and surfactant release experiments, included direct eddy correlation fluxes, detailed wave spectra, wind history, photographic retrievals of whitecap fraction, aerosol-size spectra and composition, surfactant concentration, and bubble populations in the ocean mixed layer. Measurements were made during three cruises in the northeast Atlantic on the RRS Discovery during 2006 and 2007; a fourth campaign has been making continuous measurements on the Norwegian weather ship Polarfront since September 2006. This paper provides an overview of the three projects and some of the highlights of the measurement campaigns.
    Description: As part of the U.K. contribution to the international Surface Ocean–Lower Atmosphere Study, a series of three related projects—DOGEE, SEASAW, and HiWASE—undertook experimental studies of the processes controlling the physical exchange of gases and sea spray aerosol at the sea surface. The studies share a common goal: to reduce the high degree of uncertainty in current parameterization schemes. The wide variety of measurements made during the studies, which incorporated tracer and surfactant release experiments, included direct eddy correlation fluxes, detailed wave spectra, wind history, photographic retrievals of whitecap fraction, aerosol-size spectra and composition, surfactant concentration, and bubble populations in the ocean mixed layer. Measurements were made during three cruises in the northeast Atlantic on the RRS Discovery during 2006 and 2007; a fourth campaign has been making continuous measurements on the Norwegian weather ship Polarfront since September 2006. This paper provides an overview of the three projects and some of the highlights of the measurement campaigns.
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  • 86
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    Unknown
    American Meteorological Society
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1091-1106, doi:10.1175/2007JPO3805.1.
    Description: A model of deep ocean circulation driven by turbulent mixing is produced in a long, rectangular laboratory tank. The salinity difference is substituted for the thermal difference between tropical and polar regions. Freshwater gently flows in at the top of one end, dense water enters at the same rate at the top of the other end, and an overflow in the middle removes the same amount of surface water as is pumped in. Mixing is provided by a rod extending from top to bottom of the tank and traveling back and forth at constant speed with Reynolds numbers 〉500. A stratified upper layer (“thermocline”) deepens from the mixing and spreads across the entire tank. Simultaneously, a turbulent plume (“deep ocean overflow”) from a dense-water source descends through the layer and supplies bottom water, which spreads over the entire tank floor and rises into the upper layer to arrest the upper-layer deepening. Data are taken over a wide range of parameters and compared to scaling theory, energetic considerations, and simple models of turbulently mixed fluid. There is approximate agreement with a simple theory for Reynolds number 〉1000 in experiments with a tank depth less than the thermocline depth. A simple argument shows that mixing and plume potential energy flux rates are equal in magnitude, and it is suggested that the same is approximately true for the ocean.
    Description: The research was supported by the Ocean Climate Change Institute of Woods Hole Oceanographic Institution.
    Keywords: Ocean circulation ; Mixing ; In situ observations ; Vertical motion
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  • 87
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1669-1689, doi:10.1175/2007JPO3890.1.
    Description: Spectral techniques applied to altimetry data are used to examine the dispersion relation and meridional sea level structure of wavelike variability with periods of about 20 to 200 days in the equatorial Pacific Ocean. Zonal wavenumber–frequency power spectra of sea surface height, when averaged over about 7°S–7°N, exhibit spectral peaks near the theoretical dispersion curves of first baroclinic-mode equatorial Kelvin and Rossby waves. There are distinct, statistically significant ridges of power near the first and second meridional-mode Rossby wave dispersion curves. Sea level variability near the theoretical Kelvin wave and first meridional-mode Rossby wave dispersion curves is dominantly (but not perfectly) symmetric about the equator, while variability near the theoretical second meridional-mode Rossby wave dispersion curve is dominantly antisymmetric. These results are qualitatively consistent with expectations from classical or shear-modified theories of equatorial waves. The meridional structures of these modes resemble the meridional modes of equatorial wave theory, but there are some robust features of the meridional profiles that were not anticipated. The meridional sea level structure in the intraseasonal Kelvin wave band closely resembles the theoretically expected Gaussian profile, but sea level variability coherent with that at the equator is detected as far away as 11.75°S, possibly as a result of the forced nature of these Kelvin waves. Both first and second meridional-mode Rossby waves have larger amplitude in the Northern Hemisphere. The meridional sea level structure of tropical instability waves closely resembles that predicted by Lyman et al. using a model linearized about a realistic equatorial zonal current system.
    Description: This work was supported in part by the NOAA Climate Prediction Program for the Americas (Grant NA17RJ1223).
    Keywords: Spectral analysis ; Sea level ; Dispersion ; Kelvin waves ; Rossby waves
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  • 88
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 2556-2574, doi:10.1175/2008JPO3666.1.
    Description: Vertical profiles of horizontal velocity obtained during the Mid-Ocean Dynamics Experiment (MODE) provided the first published estimates of the high vertical wavenumber structure of horizontal velocity. The data were interpreted as being representative of the background internal wave field, and thus, despite some evidence of excess downward energy propagation associated with coherent near-inertial features that was interpreted in terms of atmospheric generation, these data provided the basis for a revision to the Garrett and Munk spectral model. These data are reinterpreted through the lens of 30 years of research. Rather than representing the background wave field, atmospheric generation, or even near-inertial wave trapping, the coherent high wavenumber features are characteristic of internal wave capture in a mesoscale strain field. Wave capture represents a generalization of critical layer events for flows lacking the spatial symmetry inherent in a parallel shear flow or isolated vortex.
    Description: Salary support for this analysis was provided by Woods Hole Oceanographic Institution bridge support funds.
    Keywords: Eddies ; Ocean dynamics ; Internal waves ; Ocean variability
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  • 89
    facet.materialart.
    Unknown
    American Meteorological Society
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 1267-1277, doi:10.1175/2007JPO3906.1.
    Description: A two-layer quasigeostrophic model in a channel is used to study the influence of lateral displacements of regions of different sign mean potential vorticity gradient (Πy) on the growth rate and structure of linearly unstable waves. The mean state is very idealized, with a region of positive Πy in the upper layer and a region of negative Πy in the lower layer; elsewhere Πy is zero. The growth rate and structure of the model’s unstable waves are quite sensitive to the amount of overlap between the two regions. For large amounts of overlap (more than several internal deformation radii), the channel modes described by Phillips’ model are recovered. The growth rate decreases abruptly as the amount of overlap decreases below the internal deformation radius. However, unstable modes are also found for cases in which the two nonzero Πy regions are separated far apart. In these cases, the wavenumber of the unstable waves decreases such that the aspect ratio of the wave remains O(1). The waves are characterized by a large-scale barotropic component that has maximum amplitude near one boundary but extends all the way across the channel to the opposite boundary. Near the boundaries, the wave is of mixed barotropic–baroclinic structure with cross-front scales on the order of the internal deformation radius. The perturbation heat flux is concentrated near the nonzero Πy regions, but the perturbation momentum flux extends all the way across the channel. The perturbation fluxes act to reduce the isopycnal slopes near the channel boundaries and to transmit zonal momentum from the region of Πy 〉 0 to the region on the opposite side of the channel where Πy 〈 0. These nonzero perturbation momentum fluxes are found even for a mean state that has no lateral shear in the velocity field.
    Description: This work was supported by NSF Grants OPP-0421904, OCE-0423975 (MAS), and OCE- 85108600 (JP).
    Keywords: Baroclinic flows ; Barotropic flows
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  • 90
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 90 (2009): 1337-1350, doi:10.1175/2009BAMS2706.1.
    Description: A major oceanographic field experiment is described, which is designed to observe, quantify, and understand the creation and dispersal of weakly stratified fluid known as “mode water” in the region of the Gulf Stream. Formed in the wintertime by convection driven by the most intense air–sea fluxes observed anywhere over the globe, the role of mode waters in the general circulation of the subtropical gyre and its biogeo-chemical cycles is also addressed. The experiment is known as the CLIVAR Mode Water Dynamic Experiment (CLIMODE). Here we review the scientific objectives of the experiment and present some preliminary results.
    Description: Physical Oceanography program of NSF
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  • 91
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 541-565, doi:10.1175/2007JPO3678.1.
    Description: The impact of the Greenland tip jet on the wintertime mixed layer of the southwest Irminger Sea is investigated using in situ moored profiler data and a variety of atmospheric datasets. The mixed layer was observed to reach 400 m in the spring of 2003 and 300 m in the spring of 2004. Both of these winters were mild and characterized by a low North Atlantic Oscillation (NAO) index. A typical tip jet event is associated with a low pressure system that is advected by upper-level steering currents into the region east of Cape Farewell and interacts with the high topography of southern Greenland. Heat flux time series for the mooring site were constructed that include the enhancing influence of the tip jet events. This was used to force a one-dimensional mixed layer model, which was able to reproduce the observed envelope of mixed layer deepening in both winters. The deeper mixed layer of the first winter was largely due to a higher number of robust tip jet events, which in turn was caused by the steering currents focusing more storms adjacent to southern Greenland. Application of the mixed layer model to the winter of 1994–95, a period characterized by a high-NAO index, resulted in convection exceeding 1700 m. This prediction is consistent with hydrographic data collected in summer 1995, supporting the notion that deep convection can occur in the Irminger Sea during strong winters.
    Description: KV and RP were supported by National Science Foundation Grant OCE-0450658. GWKM was supported by the Canadian Foundation for Climate and Atmospheric Sciences. MHR was supported by the Nordic Council of Ministers (West-Nordic Ocean Climate).
    Keywords: Mixed layer ; Europe ; Wind effects ; In situ observations ; North Atlantic Oscillation
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  • 92
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 20 (2007): 5376–5390, doi:10.1175/2007JCLI1714.1.
    Description: Global estimates of oceanic evaporation (Evp) from 1958 to 2005 have been recently developed by the Objectively Analyzed Air–Sea Fluxes (OAFlux) project at the Woods Hole Oceanographic Institution (WHOI). The nearly 50-yr time series shows that the decadal change of the global oceanic evaporation (Evp) is marked by a distinct transition from a downward trend to an upward trend around 1977–78. Since the transition, the global oceanic Evp has been up about 11 cm yr−1 (10%), from a low at 103 cm yr−1 in 1977 to a peak at 114 cm yr−1 in 2003. The increase in Evp was most dramatic during the 1990s. The uncertainty of the estimates is about ±2.74 cm yr−1. By utilizing the newly developed datasets of Evp and related air–sea variables, the study investigated the cause of the decadal change in oceanic Evp. The decadal differences between the 1990s and the 1970s indicates that the increase of Evp in the 1990s occurred over a global scale and had spatially coherent structures. Larger Evp is most pronounced in two key regions—one is the paths of the global western boundary currents and their extensions, and the other is the tropical Indo-Pacific warm water pools. It is also found that Evp was enlarged primarily during the hemispheric wintertime (defined as the mean of December–February for the northern oceans and June–August for the southern oceans). Despite the dominant upward tendency over the global basins, a slight reduction in Evp appeared in such regions as the subtropical centers of the Evp maxima as well as the eastern equatorial Pacific and Atlantic cold tongues. An empirical orthogonal function (EOF) analysis was performed for the yearly winter-mean time series of Evp and the related air–sea variables [i.e., wind speed (U) and air–sea humidity differences (dq)]. The analysis suggested a dominant role of the wind forcing in the decadal change of both Evp and dq. It is hypothesized that wind impacts Evp in two ways. The first way is direct: the greater wind speed induces more evaporation by carrying water vapor away from the evaporating surface to allow the air–sea humidity gradients to be reestablished at a faster pace. The second way is indirect: the enhanced surface wind strengthens the wind-driven subtropical gyre, which in turn drives a greater heat transport by the western boundary currents, warms up SST along the paths of the currents and extensions, and causes more evaporation by enlarging the air–sea humidity gradients. The EOF analysis performed for the time series of the global annual-mean Evp fields showed that the first three EOF modes account for nearly 50% of the total variance. The mode 1 variability represents the upward trend in Evp after 1978 and is attributable to the increased U, and the mode 2 variability explains much of the downward trend in Evp before 1978 and is correlated to the global dq variability. The EOF mode 3 of Evp captures the interannual variability of Evp on time scales of the El Niño–Southern Oscillation, with the center of action over the eastern equatorial Pacific.
    Description: The author acknowledges the supporting grants from the NOAA Office of Climate Observations (OCO) and Climate Change Data and Detection (CCDD) and from the NASA Ocean Vector Wind Science Team.
    Keywords: Evaporation ; Winds ; Climatology ; Air-sea interaction ; Decadal variability
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  • 93
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 20 (2007): 2416-2433, doi:10.1175/JCLI4103.1.
    Description: North Pacific decadal oceanic and atmospheric variability is examined from a 650-yr control integration of the Community Climate System Model version 2. The dominant pattern of winter sea surface temperature (SST) variability is similar to the observed “Pacific decadal oscillation,” with maximum amplitude along the Kuroshio Extension. SST anomalies in this region exhibit significant spectral peaks at approximately 16 and 40 yr. Lateral geostrophic heat flux divergence, caused by a meridional shift of the Kuroshio Extension forced by basin-scale wind stress curl anomalies 3–5 yr earlier, is responsible for the decadal SST variability; local surface heat flux and Ekman heat flux divergence act as a damping and positive feedback, respectively. A simple linear Rossby wave model is invoked to explicitly demonstrate the link between the wind stress curl forcing and decadal variability in the Kuroshio Extension. The Rossby wave model not only successfully reproduces the two decadal spectral peaks, but also illustrates that only the low-frequency (〉10-yr period) portion of the approximately white noise wind stress curl forcing is relevant. This model also demonstrates that the weak and insignificant decadal spectral peaks in the wind stress curl forcing are necessary for producing the corresponding strong and significant oceanic peaks in the Kuroshio Extension. The wind stress curl response to decadal SST anomalies in the Kuroshio Extension is similar in structure but opposite in sign and somewhat weaker than the wind stress curl forcing pattern. These results suggest that the simulated North Pacific decadal variability owes its existence to two-way ocean–atmosphere coupling.
    Description: The first author gratefully acknowledges financial support from NOAA’s Office of Global Programs (grant to C. Deser) and the CCSM Project Office.
    Keywords: Decadal variability ; Fluxes ; Rossby waves ; Wind stress ; Coupled models
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  • 94
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 88 (2007): 527-539, doi:10.1175/bams-88-4-527.
    Description: A 25-yr (1981–2005) time series of daily latent and sensible heat fluxes over the global ice-free oceans has been produced by synthesizing surface meteorology obtained from satellite remote sensing and atmospheric model reanalyses outputs. The project, named Objectively Analyzed Air–Sea Fluxes (OAFlux), was developed from an initial study of the Atlantic Ocean that demonstrated that such data synthesis improves daily flux estimates over the basin scale. This paper introduces the 25-yr heat flux analysis and documents variability of the global ocean heat flux fields on seasonal, interannual, decadal, and longer time scales suggested by the new dataset. The study showed that, among all the climate signals investigated, the most striking is a long-term increase in latent heat flux that dominates the data record. The globally averaged latent heat flux increased by roughly 9 W m−2 between the low in 1981 and the peak in 2002, which amounted to about a 10% increase in the mean value over the 25-yr period. Positive linear trends appeared on a global scale, and were most significant over the tropical Indian and western Pacific warm pool and the boundary current regions. The increase in latent heat flux was in concert with the rise of sea surface temperature, suggesting a response of the atmosphere to oceanic forcing.
    Description: The authors gratefully acknowledge support from NOAA through the Cooperative Institute for Climate and Oceanic Research (CICOR) at the Woods Hole Oceanographic Institution (WHOI). Supporting NOAA grants are from the Office of Climate Observations (OCO) and Climate Change Data and Detection (CCDD).
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  • 95
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 20 (2007): 2760-2768, doi:10.1175/JCLI4138a.1
    Description: The correlation between parameters characterizing observed westerly wind bursts (WWBs) in the equatorial Pacific and the large-scale SST is analyzed using singular value decomposition. The WWB parameters include the amplitude, location, scale, and probability of occurrence for a given SST distribution rather than the wind stress itself. This approach therefore allows for a nonlinear relationship between the SST and the wind signal of the WWBs. It is found that about half of the variance of the WWB parameters is explained by only two large-scale SST modes. The first mode represents a developed El Niño event, while the second mode represents the seasonal cycle. More specifically, the central longitude of WWBs, their longitudinal extent, and their probability seem to be determined to a significant degree by the ENSO-driven signal. The amplitude of the WWBs is found to be strongly influenced by the phase of the seasonal cycle. It is concluded that the WWBs, while partially stochastic, seem an inherent part of the large-scale deterministic ENSO dynamics. Implications for ENSO predictability and prediction are discussed.
    Description: Eli Tziperman is supported by the U.S. National Science Foundation Climate Dynamics Program Grant ATM- 0351123 and by the McDonnell Foundation. Lisan Yu is supported by the NASA Ocean Vector Wind Science Team under JPL Contract 1216955 and NSF Climate Dynamics Grant ATM-0350266.
    Keywords: Sea surface temperature ; Wind bursts ; Tropics ; Pacific Ocean
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  • 96
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 20 (2007): 3785–3801, doi:10.1175/JCLI4234.1
    Description: The influences of strong gradients in sea surface temperature on near-surface cross-front winds are explored in a series of idealized numerical modeling experiments. The atmospheric model is the Naval Research Laboratory Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) model, which is fully coupled to the Regional Ocean Modeling System (ROMS) ocean model. A series of idealized, two-dimensional model calculations is carried out in which the wind blows from the warm-to-cold side or the cold-to-warm side of an initially prescribed ocean front. The evolution of the near-surface winds, boundary layer, and thermal structure is described, and the balances in the momentum equation are diagnosed. The changes in surface winds across the front are consistent with previous models and observations, showing a strong positive correlation with the sea surface temperature and boundary layer thickness. The coupling arises mainly as a result of changes in the flux Richardson number across the front, and the strength of the coupling coefficient grows quadratically with the strength of the cross-front geostrophic wind. The acceleration of the winds over warm water results primarily from the rapid change in turbulent mixing and the resulting unbalanced Coriolis force in the vicinity of the front. Much of the loss/gain of momentum perpendicular to the front in the upper and lower boundary layer results from acceleration/deceleration of the flow parallel to the front via the Coriolis term. This mechanism is different from the previously suggested processes of downward mixing of momentum and adjustment to the horizontal pressure gradient, and is active for flows off the equator with sufficiently strong winds. Although the main focus of this work is on the midlatitude, strong wind regime, calculations at low latitudes and with weak winds show that the pressure gradient and turbulent mixing terms dominate the cross-front momentum budget, consistent with previous work.
    Description: This work was supported by the Office of Naval Research Grant N00014-05-1-0300.
    Keywords: Fronts ; Sea surface temperature ; Wind stress ; Coupled models ; Boundary layer
    Repository Name: Woods Hole Open Access Server
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  • 97
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    American Meteorological Society
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 148–161, doi:10.1175/JPO3003.1.
    Description: As part of a program aimed at developing a long-duration, subsurface mooring, known as Ultramoor, several modern acoustic current meters were tested. The instruments with which the authors have the most experience are the Aanderaa RCM11 and the Nortek Aquadopp, which measure currents using the Doppler shift of backscattered acoustic signals, and the Falmouth Scientific ACM, which measures changes in travel time of acoustic signals between pairs of transducers. Some results from the Doppler-based Sontek Argonaut and the travel-time-based Nobska MAVS are also reported. This paper concentrates on the fidelity of the speed measurement but also presents some results related to the accuracy of the direction measurement. Two procedures were used to compare the instruments. In one, different instruments were placed close to one another on three different deep-ocean moorings. These tests showed that the RCM11 measures consistently lower speeds than either a vector averaging current meter or a vector measuring current meter, both more traditional instruments with mechanical velocity sensors. The Aquadopp in use at the time, but since updated to address accuracy problems in low scattering environments, was biased high. A second means of testing involved comparing the appropriate velocity component of each instrument with the rate of change of pressure when they were lowered from a ship. Results from this procedure revealed no depth dependence or measurable bias in the RCM11 data, but did show biases in both the Aquadopp and Argonaut Doppler-based instruments that resulted from low signal-to-noise ratios in the clear, low scattering conditions beneath the thermocline. Improvements in the design of the latest Aquadopp have reduced this bias to a level that is not significant.
    Description: This material is based upon work supported by the National Science Foundation under Grant 9810641.
    Keywords: Currents ; Acoustic measurements ; In situ sensors
    Repository Name: Woods Hole Open Access Server
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  • 98
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 1066–1076, doi:10.1175/JPO3032.1.
    Description: A 50-day time series of high-resolution temperature in the deepest layers of the Canada Basin in the Arctic Ocean indicates that the deep Canada Basin is a dynamically active environment, not the quiet, stable basin often assumed. Vertical motions at the near-inertial (tidal) frequency have amplitudes of 10– 20 m. These vertical displacements are surprisingly large considering the downward near-inertial internal wave energy flux typically observed in the Canada Basin. In addition to motion in the internal-wave frequency band, the measurements indicate distinctive subinertial temperature fluctuations, possibly due to intrusions of new water masses.
    Keywords: Arctic ; Ocean dynamics ; Ship observations
    Repository Name: Woods Hole Open Access Server
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  • 99
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 394-407, doi:10.1175/jpo3018.1.
    Description: The ability of paleoceanographic tracers to constrain rates of transport is examined using an inverse method to combine idealized observations with a geostrophic model. Considered are the spatial distribution, accuracy, and types of tracers required to constrain changes in meridional transport within an idealized single-hemisphere basin. Measurements of density and radioactive tracers each act to constrain rates of transport. Conservative tracers, while not of themselves able to inform regarding rates of transport, improve constraints when coupled with density or radioactive observations. It is found that the tracer data would require an accuracy one order of magnitude better than is presently available for paleo-observations to conclusively rule out factor-of-2 changes in meridional transport, even when assumed available over the entire model domain. When data are available only at the margins and bottom of the model, radiocarbon is unable to constrain transport while density remains effective only when a reference velocity level is assumed. The difficulty in constraining the circulation in this idealized model indicates that placing firm bounds on past meridional transport rates will prove challenging.
    Description: The first author is supported by the NOAA Postdoctoral Program in Climate and Global Change and GG by the National Ocean Partnership Program (ECCO). Author OM acknowledges support from the National Science Foundation.
    Keywords: Tracers ; Transport ; Paleoclimatology ; Ocean models
    Repository Name: Woods Hole Open Access Server
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  • 100
    Publication Date: 2022-05-25
    Description: Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 1918-1938, doi:10.1175/jpo3089.1.
    Description: The interannual variability in upper-ocean (0–400 m) temperature and governing mechanisms for the period 1968–97 are quantified from a global ocean hindcast simulation driven by atmospheric reanalysis and satellite data products. The unconstrained simulation exhibits considerable skill in replicating the observed interannual variability in vertically integrated heat content estimated from hydrographic data and monthly satellite sea surface temperature and sea surface height data. Globally, the most significant interannual variability modes arise from El Niño–Southern Oscillation and the Indian Ocean zonal mode, with substantial extension beyond the Tropics into the midlatitudes. In the well-stratified Tropics and subtropics, net annual heat storage variability is driven predominately by the convergence of the advective heat transport, mostly reflecting velocity anomalies times the mean temperature field. Vertical velocity variability is caused by remote wind forcing, and subsurface temperature anomalies are governed mostly by isopycnal displacements (heave). The dynamics at mid- to high latitudes are qualitatively different and vary regionally. Interannual temperature variability is more coherent with depth because of deep winter mixing and variations in western boundary currents and the Antarctic Circumpolar Current that span the upper thermocline. Net annual heat storage variability is forced by a mixture of local air–sea heat fluxes and the convergence of the advective heat transport, the latter resulting from both velocity and temperature anomalies. Also, density-compensated temperature changes on isopycnal surfaces (spice) are quantitatively significant.
    Description: This work was supported in part from NOAA Office of Global Programs ACCP Grant NA86GP0290, NSF Grant OCE96-33681, and the WHOI Ocean and Climate Change Institute.
    Keywords: Temperature ; Interannual variability ; Advection ; Heating ; Air–sea interaction
    Repository Name: Woods Hole Open Access Server
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