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  • Springer  (948,991)
  • Wiley  (348,630)
  • Copernicus  (119,713)
  • 2015-2019  (738,002)
  • 2010-2014  (661,708)
  • 1945-1949  (17,624)
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  • 1
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    Landforms and landscapes of Mount Etna (Sicily): relationships between a volcano, its environment and human activity (2018)
    Springer | Springer
    Details
    Publication Date: 2020-10-13
    Description: Mount Etna is the highest relief in Sicily and represents a unique environment because of its long established and almost continuous eruptive activity, that has moulded its landforms and which has produced distinctive landscapes. Over the past 60 ka both destructive and constructive geological processes have produced the principal morphological features of the volcano such as the wide Valle del Bove depression, monogenic scoria cones and extensive lava flow fields. Relationships between Etna, its environment and human activity began in the Neolithic Period within the mountain foot region and have developed over millennia. Even though there has been a rapid rate of resurfacing by lava during historic times, the impact on human activity has been short-lived, recovery has been rapid and society has adjusted to the ever present hazard in distinctive ways.
    Description: Published
    Description: 467-478
    Description: 1V. Storia eruttiva
    Description: N/A or not JCR
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 2
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    Towards an automatic monitoring system of infrasonic events at Mt. Etna: strategies for source location and modelling (2010)
    Springer
    Details
    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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  • 3
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    Supporting the Development of Procedures for Communications During Volcanic Emergencies: Lessons Learnt from the Canary Islands (Spain) and Etna and Stromboli (Italy) (2017)
    Springer
    Details
    Publication Date: 2020-11-18
    Description: Volcanic crises are complex and especially challenging to manage. Volcanic unrest is characterised by uncertainty about whether an eruption will or will not take place, as well as its possible location, size and evolution. Planning is further complicated by the range of potential hazards and the variety of disciplines involved in forecasting and responding to volcanic emergencies. Effective management is favoured at frequently active volcanoes, owing to the experience gained through the repeated ‘testing’ of systems of communication. Even when plans have not been officially put in place, the groups involved tend to have an understanding of their roles and responsibilities and those of others. Such experience is rarely available at volcanoes that have been quiescent for several generations. Emergency responses are less effective, not only because of uncertainties about the volcanic system itself, but also because scientists, crisis directors, managers and the public are inexperienced in volcanic unrest. In such situations, tensions and misunderstandings result in poor communication and have the potential to affect decision making and delay vital operations. Here we compare experiences on communi- cating information during crises on volcanoes reawakening after long repose (El Hierro in the Canary Islands) and in frequent eruption (Etna and Stromboli in Sicily). The results provide a basis for enhancing commu- nication protocols during volcanic emergencies.
    Description: Published
    Description: 1-17
    Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Description: N/A or not JCR
    Keywords: Etna volcano ; Stromboli volcano ; Canary Islands ; volcanic emergencies ; communication ; volcanic crisis ; Procedures for Communications During Volcanic Emergencies ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 4
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    On the Propagation Path of Magma‐Filled Dikes and Hydrofractures: The Competition Between External Stress, Internal Pressure, and Crack Length (2019)
    Wiley
    Details
    Publication Date: 2021-03-09
    Description: Mixed‐mode fluid‐filled cracks represent a common means of fluid transport within the Earth's crust. They often show complex propagation paths which may be due to interaction with crustal heterogeneities or heterogeneous crustal stress. Previous experimental and numerical studies focus on the interplay between fluid over-pressure and external stress but neglect the effect of other crack parameters. In this study, we address the role of crack length on the propagation paths in the presence of an external heterogeneous stress field. We make use of numerical simulations of magmatic dike and hydrofracture propagation, carried out using a two‐dimensional boundary element model, and analogue experiments of air‐filled crack propagation into a transparent gelatin block. We use a 3‐D finite element model to compute the stress field acting within the gelatin block and perform a quantitative comparison between 2‐D numerical simulations and experiments. We show that, given the same ratio between external stress and fluid pressure, longer fluid‐filled cracks are less sensitive to the background stress, and we quantify this effect on fluid‐filled crack paths. Combining the magnitude of the external stress, the fluid pressure, and the crack length, we define a new parameter, which characterizes two end member scenarios for the propagation path of a fluid‐filled fracture. Our results have important implications for volcanological studies which aim to address the problem of complex trajectories of magmatic dikes (i.e., to forecast scenarios of new vents opening at volcanoes) but also have implications for studies that address the growth and propagation of natural and induced hydrofractures.
    Description: Published
    Description: 2064–2081
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: Magmatic dykes ; hydrofractures ; Numerical symulations ; Analogue experiments ; 04.08. Volcanology ; 05.05. Mathematical geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Geochemistry of volcanic fluids : A special issue of the Bulletin of Volcanology in honour of Yuri A. Taran (2011)
    Springer
    Details
    Publication Date: 2021-05-17
    Description: This special issue is dedicated to Yuri Taran's outstanding contributions to gas geochemistry that began in the early 1980s with his work on deuterium and 18O compositions of geothermal waters in the Mutnovsky (Kamchatka) region and continues to this day with work on the Kamchatka volcanic volatile budget, carbon isotopes of hydrocarbons, and new insights into the geochemistry of El Chichón volcano, Chiapas. Yuri has contributed greatly to the field of volcanic gas geochemistry and was the first to recognize the distinct deuterium and oxygen isotopic composition of fumarole condensates from volcanoes in Kamchatka (Taran et al. 1987a). The shift in δD and δ18O to significantly heavier values compared to local meteoric water led Yuri to introduce the term “andesitic water” (Taran et al. 1989a, b) which has since been recognized at subduction zone volcanoes globally. This distinct isotopic composition is evidence that volcanoes release water that ultimately originates as subducted seawater and is recycled through the mantle wedge back to the earth's surface. Yuri's early work on the gas emissions from Kamchatka and Kurile Islands volcanoes also included the development and testing of gas geothermometers (Taran 1986) and investigating hydrothermal alteration using isotopic data (Taran et al. 1987b). His curiosity remained focused on the isotope systematics of volcanic gases discharging from Kamchatka and the Kuriles through the late 1980s and 1990s with publications on the gas compositions of Klyuchevskoi (Taran et al. 1991), Mutnovsky (Taran et al. 1992), Avachinsky and Koryaksky (Taran et al. 1997). Yuri was involved in the discovery of a pure and unique rhenium mineral on Kudryavy volcano (Korzhinsky et al. 1994) and provided one of the most detailed chemical studies of high temperature (up to 950°C) fumaroles to date of any volcano (Taran et al. 1995). His 1995 paper on Kudryavy remains highly cited and provides the highest quality volcanic gas data which also include trace elements from a subduction zone. Such data are crucial when we attempt to interpret lower temperature volcanic gas compositions or calculate rare metal fluxes from volcanoes worldwide. His most recent publication on Kamchatka-Kurile volcanic emissions provides a detailed analysis of the total gas flux from these volcanoes (Taran 2009).
    Description: Published
    Description: 369-371
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: Fluids Geochemistry ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
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    Early-middle Holocene land snail shell stable isotope record from Grotta di Latronico 3 (southern Italy) (2011)
    Wiley
    Details
    Publication Date: 2021-04-07
    Description: This paper compares stable isotope (δ18O and δ13C) records of early–middle Holocene land snail shells from the archaeological deposits of Grotta di Latronico 3 (LTR3; southern Italy) with modern shell isotopic data. No substantial interspecific variability was observed in shell δ18O (δ18Os) of modern specimens (Pomatias elegans, Cornu aspersum, Eobania vermiculata, Helix ligata and Marmorana fuscolabiata). In contrast, interspecific shell δ13C (δ13Cs) variability was significant, probably due to different feeding behaviour among species. The δ18Os values of living land snails suggest that species hibernate for a long period during colder months, so that the signal of 18O-depleted winter rainfall in their δ18Os is lost. This suggests that δ18Os and δ13Cs values of Pomatias elegans from this archaeological succession provide valuable clues for seasonal (spring–autumn) climatic conditions during the early–middle Holocene. The δ18Os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records, suggesting a substantial increase of precipitation and/or persistent changes in air mass source trajectories over this region between ca. 8.8 cal ka BP and 6.2–6.7 ka ago. The δ13Cs trend suggests a transition from a slightly 13C-enriched to a 13C-depleted diet between early and middle Holocene compared to present conditions. We postulate that this δ13Cs trend might reflect changes in the C3 vegetation community, potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric CO2 concentration. Copyright © 2010 John Wiley & Sons, Ltd.
    Description: Published
    Description: 1347-1359
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: central Mediterranean ; archaeological succession ; land snail shells ; stable isotopes ; palaeoclimate ; 03. Hydrosphere::03.01. General::03.01.03. Global climate models
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    Improvement of microseismic monitoring at the gas storage concession “Minerbio Stoccaggio” (Bologna, Northern Italy) (2019)
    Springer
    Details
    Publication Date: 2020-10-22
    Description: The storage concession "Minerbio Stoccaggio" (Bologna, Northern Italy) covers a 69 km 2 area, 65% of hich is located in the Minerbio municipality. Since 1979, a microseismic network for the monitoring of seismicity, eventually induced by gas storage activities, has been installed in this area. The network was operated by Stogit S.p.A, a subsidiary company of Snam, which is the largest storage operator in Italy. In 2016, the microseismic network, consisting of three surface stations and one 100-m-deep borehole sensor with minimum interstation distances of about 3.0 km, was integrated with 12 regional stations installed in an 80 × 80 km 2 area centered on the surface projection of the reservoir. In 2018, the microseismic network was enhanced by adding one surface and three 150-m-deep borehole stations. In this work, we evaluate the detection improvement of the microseismic network, integrated with the regional stations. We define two crustal volumes for earthquake detection: the inner domain of detection, IDD (10 × 10 × 5) km 3 , within which we should ensure the highest network performance, and the extended domain of detection, EDD (22 × 22 × 11) km 3 . By comparing the simulated power spectral density of hypothetical seismic sources located in EDD with the average power spectra of ambient seismic noise observed at each station site, we calculate detection and localization thresholds for the two above-mentioned networks. Under unfavourable noise conditions, we find that the present operative seismic network allows locating earthquakes with M L ≥ 0.8 occurring at the depth of the reservoir and with M L ≥ 1.0 if located within IDD.
    Description: Funding information This study received financial support from BComune di Minerbio^ under the grant BSperimentazione ILG Minerbio^ (grant number 0913.010)
    Description: Published
    Description: 967–977
    Description: 3SR TERREMOTI - Attività dei Centri
    Description: JCR Journal
    Keywords: Induced seismicity ; Earthquake detection ; Ambient seismic noise ; Microseismic monitoring ; MiSE ; oilfield monitoring guidelines
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Long-Term Disaster-Prevention Strategies Based on Education (2015)
    Springer
    Details
    Publication Date: 2020-12-23
    Description: Although human behavior is the crucial factor in the degree of vulnerability and the likelihood of disasters taking place, preparedness and prevention programs are not mandatory in all countries around the world. Within the framework of UPStrat-MAFA (Urban disaster Prevention Strategies using MAcroseismic FAults), we have defined the disaster prevention strategies based on education management information and actions taken in Iceland, Portugal, Spain, and Italy. A detailed comparative study shows that compulsory school in these four participating countries is greatly unprepared with regard to hazard education, and these results are in line with worldwide studies. Moreover, when hazards are addressed, this is not done at an early age, which results in a missed chance to intervene in the noncognitive side of awareness, which decreases at later ages. To comply with the urge to take actions towards training and education at an early age, we used hands-on tools and learn-by-playing approaches in an informal learning environment. To reach the older population, the audio- visual media appears to be the best and lowest cost alternative to promote risk perception, awareness and education.
    Description: Published
    Description: 77-80
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: restricted
    Keywords: Disaster prevention ; Education ; Seismic hazard ; Information strategies ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 9
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    The CLIVAR C20C Project: Which components of the Asian-Australian monsoon circulation variations are forced and reproducible? (2010)
    Springer
    Details
    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)
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  • 10
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    Historical faulting as the possible cause of earthquake damages in the ancient Roman port city of Ostia (2019)
    Springer
    Details
    Publication Date: 2020-09-07
    Description: This paper presents an original multidisciplinary (geological-structural-geomorphological and seismological) study aimed at investigating the origin of diffused seismic damages affecting several ancient buildings in the Roman port city of Ostia. We also evaluate the possibility to relate these damages to a previously hypothesized ENE-WSW trending fault, bordering the morphological height upon which the Ostia town was founded. Aimed at this scope, we performed seismic noise measures (by using 14 seismic stations) that show no significantly different response and lack of significant ground motion differential amplifications. The coexistence of (i) no local geological heterogeneities and (ii) low amplification of spectral ratios in the recorded seismic signals seems to exclude that the observed seismic damage may be the consequence of significant site effects. When also the large distance from the strongest Apennine’s seismogenic source areas is considered, the possibility that the observed damage may be the consequence of local events should be considered. We discuss the potentiality of the ENE-WSW trending fault as the source of the observed seismic damages, highlighting the supporting evidence as well as the uncertainties of such interpretation.
    Description: Published
    Description: 833–851
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
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  • 11
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    2016–2017 Central Italy seismic sequence: strong-motion data analysis and design earthquake selection for seismic microzonation purposes (2019)
    Springer
    Details
    Publication Date: 2020-09-07
    Description: This work describes the analysis of the strong-motion data from the Engineering Strong Motion database (ESM, http://esm.mi.ingv.it), aimed at: (1) extract a dataset of accelero- metric waveforms recorded during the 2016–2017 Central Italy seismic sequence; (2) iden- tify the recording stations to be used as reference sites for further seismological analysis; (3) select the records to be used as input for seismic microzonation of higher level at 137 municipalities. Firstly, a residual analysis is carried out on the extracted dataset to perform: (1) the quality check of the waveforms recorded by temporary networks installed soon after the occurrence of the rst main shock (M 6.0, 24 August 2016); (2) the estimation of the site-to-site residual term for each recording station with the aim of recognising potential reference rock sites. Finally, the software REXELite, integrated within the ESM website, is adopted to select suites of spectrum-compatible accelerograms, that will be used as input for calculating site ampli cations through 1D and 2D simulations at sites which suf- fered the greatest damage. The results of this work demonstrate the success of the synergy among Italian institutions. The setup of key infrastructures, such as emergency networks and data repositories, together with the knowledge developed during national projects, turned out to be successful in terms of timely intervention during the emergency phase and the planning of the post-emergency.
    Description: Published
    Description: 5533–5551
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Communicating Information on Eruptions and Their Impacts from the Earliest Times Until the Late Twentieth Century (2018)
    Springer
    Details
    Publication Date: 2020-10-13
    Description: Volcanoes hold a fascination for human beings and, before they were recorded by literate observers, eruptions were portrayed in art, were recalled in legend and became incorporated into religious practices: being viewed as agents of punishment, bounty or intimidation depending upon their state of activity and the culture involved. In the Middle East the earliest record dates from the third millennium BCE and knowledge of volcanoes increased progressively over time. In the first century CE written records noted nine volcanoes in the Mediterranean region plus Mount Cameroon in West Africa, yet by 1380 AD the record only totalled 48, with volcanoes in Japan, Indonesia and Iceland being added. After this the list of continued to increase, but important regions such as New Zealand and Hawaii were only added during the last 200 years. Only from 1900 did the rate of growth decline significantly, but it is sobering to recall that in the twentieth century major eruptions have occurred from volcanoes that were considered inactive or extinct, examples including: Mount Lamington—Papua New Guinea, 1951; Mount Arenal—Costa Rica, 1968 and Nyos—Cameroon, 1986. Although there were instances where the human impact of historical eruptions were studied in detail, with examples including the 1883 eruption of Krakatau and 1943–1952 eruption of Parícutin, these were exceptions and before 1980 there was a significant knowledge gap about both the short and long-term effects of major eruptions on societies. Following a global review, this chapter provides a discussion of the ways in which information has been collected, compiled and disseminated from the earliest times until the 1980s in two case study areas: the Azores Islands (Portugal) and southern Italy. In Italy information on eruptions stretches back to prehistoric times and has become progressively better known over more than 2,000 years, yet even here there remain significant gaps in the record even for events that took place between 1900 and 1990. In contrast, located in the middle of the Atlantic, the Azores have been isolated for much of their history and illustrate the difficulties involved in using indigenous sources to compile, not only assessments of impact, but also at a more basic level a complete list of historical events with accurate dates.
    Description: Published
    Description: 1-25
    Description: 1V. Storia eruttiva
    Description: N/A or not JCR
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 13
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    Detection of quarry and mine blast contamination in European regional catalogues (2010)
    Springer
    Details
    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
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  • 14
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    The European experience of educational seismology (2015)
    Springer
    Details
    Publication Date: 2020-11-25
    Description: This chapter provides an overview of last two decades, European experiences in educational seismology and describes the different contexts in which they have been developed. The basic idea of these educational projects is that Seismology may represent an efficient communication vehicle for teaching a wide range of basic Earth sci-ence topics through laboratory practices and educational activities. Moreover it is also an effective tool to raise in the young citizens the awareness on the earthquake risk and possible mitigation actions. In this frame several seismic stations with different technologies were installed in schools across Europe. The scientific support of re-searchers and the need to establish strong links between teachers and researchers attribute to the school an active role in the knowledge process using the scientific laboratory practice by adopting the “learning by doing” modern approach of science communication (R. Schank and C. Cleary, 1995, Engines for Education, Ed. Routledge, 248 pp). Some educational activities correlated with seismological projects are presented, following different strategies depending on the country, but all aimed at building a new way to communicate science in the schools. The new vogue is the opening toward social networks and blogs. This generalizes the concept of an educational Geoscience website making it an e-platform for science communication and multimedia data sharing, where researchers, teachers, students and education op-erators can interact and constantly be kept informed of ongoing activities and relevant events. All of these 'seismology at school' initiatives rely on the concept of school networking and will merge in the European project NERA (Network of European Research Infrastructures for Earthquake Risk Assessment and Mitigation, http://www.nera-eu.org/) where a spe-cific workpackage is dedicated to networking school seismology programs.
    Description: Published
    Description: 145-170
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: restricted
    Keywords: educational seismology ; educational projects ; learning by doing ; science communication ; school seismology ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 15
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    Surface latent heat flux anomalies before the MS 7.1 New Zealand earthquake 2010 (2011)
    Springer
    Details
    Publication Date: 2020-11-18
    Description: By analyzing surface latent heat flux (SLHF) data from the NCEP/NCAR Reanalysis Project for the period three months before and after the Sept. 3, 2010 MS 7.1 New Zealand earthquake, an isolated SLHF positive anomaly on Aug. 1, 2010 was found with a high value of about 160 W/m2 to the northeast of the epicenter. Historical data, background pixels, and wavelet transforms of time series were comprehensively analyzed to study the spatiotemporal features of the SLHF anomaly. After removing the influences of wind speed and cloud cover, the key factor leading to local SLHF anomalies is the surface temperature increment. Combined with GPS displacement observations and tectonic settings, we determined that the physical mechanism of the SLHF anomaly could possibly be attributed to hot underground materials related to high-temperature and high-pressure upwelling from the deep crust and mantle along the nearby subduction zone, thereby explaining the local temperature increment to the northeast of the epicenter, as well as in the center of the North Island and the southwest of the South Island. Furthermore, it changed the specific humidity between the ground and surface air, causing the local SLHF increment.
    Description: Published
    Description: 3273-3280
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: open
    Keywords: remote sensing ; earthquakes ; precursors ; 01. Atmosphere::01.01. Atmosphere::01.01.05. Radiation ; 04. Solid Earth::04.02. Exploration geophysics::04.02.05. Downhole, radioactivity, remote sensing, and other methods ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
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  • 16
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    Sedimentary processes on the Wilkes Land continental rise reflect changes in glacial dynamic and bottom water flow (2011)
    Springer
    Details
    Publication Date: 2020-12-15
    Description: Four sediment cores were analysed in order to determine the sedimentary processes associated with the channel-ridge depositional system that characterise the George V Land continental margin on the Wilkes Land. The sedimentary record indicates that the WEGA channel was a dynamic turbiditic system up to M.I.S. 11. After this time, the channel became a lower-energy environment with sediments delivered to the channel through high-density bottom waters that we identify to be the high salinity shelf waters (HSSW) forming on the shelf area. The HSSW entrains the fine-grained sediments of the shelf area and deliver them to the continental rise. The biostratigraphy and facies of the sediments within the WEGA channel indicate that the HSSW down flow was active also during last glacial. The change from a turbiditic system to a lowenergy bottom current system within the WEGA channel likely reflects a different ice-flow pattern, with ice-sheet reaching the continental shelf edge only within the ice trough (ice stream).
    Description: Published
    Description: 909 - 926
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: JCR Journal
    Description: restricted
    Keywords: High salinity shelf water ; Turbidity currents ; Glacio-marine depositional processes ; Marine isotopic stage 11 ; Glacial dynamic changes ; 02. Cryosphere::02.02. Glaciers::02.02.05. Ice dynamics ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Development and decline of the ancient Harbor of Neapolis (2018)
    Wiley
    Details
    Publication Date: 2021-07-14
    Description: Archaeological exavations,undertaken since 2004 for the construction of the new Naples subway
    Description: Published
    Description: 542-557
    Description: 1V. Storia eruttiva
    Description: JCR Journal
    Keywords: A.D.79 eruption ; compositional data analysis ; geoarchaeology ; 04.08. Volcanology
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  • 18
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    The recording stations of the Italian strong motion network: geological information and site classification (2012)
    Springer
    Details
    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
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  • 19
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    Information background of 11th-15th centuries earthquakes located by the current catalogues in Vrancea (Romania) (2010)
    Springer
    Details
    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
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  • 20
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    Applying the Disruption Index Procedure to Evaluate the Urban Seismic Risk in the Mt. Etna Area (Italy) (2015)
    Springer
    Details
    Publication Date: 2020-12-23
    Description: The Disruption Index is used here for the assessment of urban disruption in the Mt. Etna area after a natural disaster. The first element of the procedure is the definition of the seismic input, which is based on information about the historical seismicity and seismogenic faults. The second element is the computation of the seismic impact on the building stock and infrastructure in the region considered. Information on urban-scale vulnerability was collected and a geographic information system was used to organize the data relating to buildings and network systems (e.g., typologies, schools, strategic structures, lifelines). The central idea underlying the definition of the Disruption Index is the identification and evaluation of the impacts on a target community, considering the physical elements that contribute most to the severe disruption. The results of this study are therefore very useful for earthquake preparedness planning and for the development of strategies to minimize the risks from earthquakes. This study is a product of the European “Urban Disaster Prevention Strategies using Macroseismic Fields and Fault Sources” project (UPStrat-MAFA European project 2013).
    Description: Published
    Description: Torino
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: open
    Keywords: Seismic impact ; Disruption index ; Urban system ; Risk measures ; Mt. Etna area (Italy) ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 21
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    New coring study in Augusta Bay expands understanding of offshore tsunami deposits (Eastern Sicily, Italy) (2019)
    Wiley
    Details
    Publication Date: 2021-01-25
    Description: Tsunami deposits present an important archive for understanding tsunami histories and dynamics. Most research in this field has focused on onshore preserved remains, while the offshore deposits have received less attention. In 2009, during a coring campaign with theItalian Navy Magnaghi, four 1 m long gravity cores (MG cores) were sampled from the northern part of Augusta Bay, along a transect in 60 to 110 m water depth. These cores were taken in the same area where a core (MS06) was collected in 2007 about 2.3 km offshore Augusta at a water depth of 72 m below sea level. Core MS06 consisted of a 6.7 m long sequence that included 12 anomalous intervals interpreted as the primary effect of tsunami backwash waves in the last 4500 years. In this study, tsunami deposits were identified, based on sedimentology and displaced benthic foraminifera (as for core MS06) reinforced by X-ray fluorescence data. Two erosional surfaces (L1 and L2) were recognized coupled with grain size increase, abundant Posidonia oceanica seagrass remains and a significant amount of Nubecularia lucifuga, an epiphytic sessile benthic foraminifera considered to be transported from the inner shelf. The occurrence of Ti/Ca and Ti/Sr increments, coinciding with peaks in organic matter (Mo inc/coh) suggests terrestrial run-off coupled with an input of organic matter. The L1 and L2 horizons were attributed to two distinct historical tsunamis (AD 1542 and AD 1693) by indirect age-estimation methods using 210Pb profiles and the comparison of Volume Magnetic Susceptibility data between MG cores and MS06 cores. One most recent bioturbated horizon (Bh), despite not matching the above listed interpretative features, recorded an important palaeoenvironmental change that may correspond to the AD 1908 tsunami. These findings reinforce the value of offshore sediment records as an underutilized resource for the identification of past tsunamis.
    Description: Published
    Description: 1553-1576
    Description: 6T. Studi di pericolosità sismica e da maremoto
    Description: JCR Journal
    Keywords: Eastern Sicily ; tsunami ; foraminifera ; sedimentology ; XRF core scanning ; 04.04. Geology
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  • 22
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    New insights into fault activation and stress transfer between en echelon thrusts: The 2012 Emilia, Northern Italy, earthquake sequence (2018)
    Wiley
    Details
    Publication Date: 2021-05-17
    Description: Here we present the results of the inversion of a new geodetic data set covering the 2012 Emilia seismic sequence and the following 1 year of postseismic deformation. Modeling of the geodetic data together with the use of a catalog of 3-D relocated aftershocks allows us to constrain the rupture geometries and the coseismic and postseismic slip distributions for the two main events (Mw 6.1 and 6.0) of the sequence and to explore how these thrust events have interacted with each other. Dislocation modeling reveals that the first event ruptured a slip patch located in the center of the Middle Ferrara thrust with up to 1 m of reverse slip. The modeling of the second event, located about 15 km to the southwest, indicates a main patch with up to 60 cm of slip initiated in the deeper and flatter portion of the Mirandola thrust and progressively propagated postseismically toward the top section of the rupture plane, where most of the aftershocks and afterslip occurred. Our results also indicate that between the two main events, a third thrust segment was activated releasing a pulse of aseismic slip equivalent to a Mw 5.8 event. Coulomb stress changes suggest that the aseismic event was likely triggered by the preceding main shock and that the aseismic slip event probably brought the second fault closer to failure. Our findings show significant correlations between static stress changes and seismicity and suggest that stress interaction between earthquakes plays a significant role among continental en echelon thrusts.
    Description: Published
    Description: 4742–4766
    Description: 1T. Deformazione crostale attiva
    Description: 2T. Sorgente Sismica
    Description: 3T. Storia Sismica
    Description: JCR Journal
    Keywords: continental tectonics ; source geometry ; geodetic modeling ; coulomb stress ; 04. Solid Earth
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  • 23
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    Remote sensing of aerosols in the Arctic for an evaluation of global climate model simulations (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Atmospheres, Wiley, 119(13), pp. 8169-8188, ISSN: 0148-0227
    Details
    Publication Date: 2020-03-05
    Description: In this study MODerate resolution Imaging Spectroradiometer (MODIS) Aqua retrievals of aerosol optical thickness (AOT) at 555 nm are compared to sun-photometer measurements from Svalbard for a period of 9 years. For the 642 daily coincident measurements that were obtained, MODIS AOT generally varies within the predicted uncertainty of the retrieval over ocean (ΔAOT = ±0.03 ± 0.05 · AOT). The results from the remote sensing have been used to examine the accuracy in estimates of aerosol optical properties in the Arctic, generated by global climate models and from in-situ measurements at the Zeppelin station, Svalbard. AOT simulated with the Norwegian Earth System Model (NorESM1-M)/ CAM4-Oslo global climate model does not reproduce the observed seasonal variability of the Arctic aerosol. The model overestimates clear-sky AOT by nearly a factor of 2 for the background summer season, while tending to underestimate the values in the spring season. Furthermore, large differences in all-sky AOT of up to one order of magnitude are found for the Coupled Model Intercomparison Project (CMIP5) model ensemble for the spring and summer seasons. Large differences between satellite/ground-based remote sensing of AOT and AOT estimated from dry and humidified scattering coefficients are found for the subarctic marine boundary layer in summer.
    Repository Name: EPIC Alfred Wegener Institut
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  • 24
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    Climate sensitivity across marine domains of life: limits to evolutionary adaptation shape species interactions (2014)
    Wiley
    In:  EPIC3Global Change Biology, Wiley, ISSN: 1365-2486
    Details
    Publication Date: 2019-07-16
    Description: Organisms in all domains, Archaea, Bacteria, and Eukarya will respond to climate change with differential vulnerabilities resulting in shifts in species distribution, coexistence, and interactions. The identification of unifying principles of organism functioning across all domains would facilitate a cause and effect understanding of such changes and their implications for ecosystem shifts. For example, the functional specialization of all organisms in limited temperature ranges leads us to ask for unifying functional reasons. Organisms also specialize in either anoxic or various oxygen ranges, with animals and plants depending on high oxygen levels. Here, we identify thermal ranges, heat limits of growth, and critically low (hypoxic) oxygen concentrations as proxies of tolerance in a meta-analysis of data available for marine organisms, with special reference to domain-specific limits. For an explanation of the patterns and differences observed, we define and quantify a proxy for organismic complexity across species from all domains. Rising complexity causes heat (and hypoxia) tolerances to decrease from Archaea to Bacteria to uni- and then multicellular Eukarya. Within and across domains, taxon-specific tolerance limits likely reflect ultimate evolutionary limits of its species to acclimatization and adaptation. We hypothesize that rising taxon-specific complexities in structure and function constrain organisms to narrower environmental ranges. Low complexity as in Archaea and some Bacteria provide life options in extreme environments. In the warmest oceans, temperature maxima reach and will surpass the permanent limits to the existence of multicellular animals, plants and unicellular phytoplankter. Smaller, less complex unicellular Eukarya, Bacteria, and Archaea will thus benefit and predominate even more in a future, warmer, and hypoxic ocean.
    Repository Name: EPIC Alfred Wegener Institut
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  • 25
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    Potential effects of climate change on the distribution range of the main silicate sinker of the Southern Ocean (2014)
    Wiley
    In:  EPIC3Ecology and Evolution, Wiley, 4(16), pp. 3147-3161, ISSN: 2045-7758
    Details
    Publication Date: 2014-09-24
    Description: Fragilariopsis kerguelensis, a dominant diatom species throughout the Antarctic Circumpolar Current, is coined to be one of the main drivers of the biological silicate pump. Here, we study the distribution of this important species and expected consequences of climate change upon it, using correlative species distribution modeling and publicly available presence-only data. As experience with SDM is scarce for marine phytoplankton, this also serves as a pilot study for this organism group. Southern Ocean. We used the maximum entropy method to calculate distribution models for the diatom F. kerguelensis based on yearly and monthly environmental data (sea surface temperature, salinity, nitrate and silicate concentrations). Observation data were harvested from GBIF and the Global Diatom Database, and for further analyses also from the Hustedt Diatom Collection (BRM). The models were projected on current yearly and seasonal environmental data to study current distribution and its seasonality. Furthermore, we projected the seasonal model on future environmental data obtained from climate models for the year 2100. Projected on current yearly averaged environmental data, all models showed similar distribution patterns for F. kerguelensis. The monthly model showed seasonality, for example, a shift of the southern distribution boundary toward the north in the winter. Projections on future scenarios resulted in a moderately to negligibly shrinking distribution area and a change in seasonality. We found a substantial bias in the publicly available observation datasets, which could be reduced by additional observation records we obtained from the Hustedt Diatom Collection. Present day distribution patterns inferred from the models coincided well with background knowledge and previous reports about F. kerguelensis distribution, showing that maximum entropy-based distribution models are suitable to map distribution patterns for oceanic planktonic organisms. Our scenario projections indicate moderate effects of climate change upon the biogeography of F. kerguelensis.
    Repository Name: EPIC Alfred Wegener Institut
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    A first Glimpse at the genome of the Baikalian amphipod Eulimnogammarus verrucosus (2014)
    Wiley
    In:  EPIC3Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, Wiley, 322(3), pp. 177-189, ISSN: 1552-5007
    Details
    Publication Date: 2014-07-21
    Description: Eulimnogammarus verrucosus is an amphipod endemic to the unique ecosystem of Lake Baikal and serves as an emerging model in ecotoxicological studies. We report here on a survey sequencing of its genome as a first step to establish sequence resources for this species. From a single lane of paired-end sequencing data, we estimated the genome size as nearly 10 Gb and we obtained an overview of the repeat content. At least two-thirds of the genome are non-unique DNA, and a third of the genomic DNA is composed of just five families of repetitive elements, including low-complexity sequences. Attempts to use off-the-shelf assembly tools failed on the available low-coverage data both before and after removal of highly repetitive components. Using a seed-based approach we nevertheless assembled short contigs covering 33 pre-microRNAs and the homeodomain-containing exon of nine Hox genes. The absence of clear evidence for paralogs implies that a genome duplication did not contribute to the large genome size. We furthermore report the assembly of the mitochondrial genome using a new, guided “crystallization” procedure. The initial results presented here set the stage for a more complete sequencing and analysis of this large genome.
    Repository Name: EPIC Alfred Wegener Institut
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  • 27
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    Latent heat exchange in the boreal and arctic biomes (2014)
    Wiley
    In:  EPIC3Global Change Biology, Wiley, pp. n/a–n/a, ISSN: 1365-2486
    Details
    Publication Date: 2021-07-19
    Description: In this study latent heat flux (λE) measurements made at 65 boreal and arctic eddy-covariance (EC) sites were analyses by using the Penman–Monteith equation. Sites were stratified into nine different ecosystem types: harvested and burnt forest areas, pine forests, spruce or fir forests, Douglas-fir forests, broadleaf deciduous forests, larch forests, wetlands, tundra and natural grasslands. The Penman–Monteith equation was calibrated with variable surface resistances against half-hourly eddy-covariance data and clear differences between ecosystem types were observed. Based on the modeled behavior of surface and aerodynamic resistances, surface resistance tightly control λE in most mature forests, while it had less importance in ecosystems having shorter vegetation like young or recently harvested forests, grasslands, wetlands and tundra. The parameters of the Penman–Monteith equation were clearly different for winter and summer conditions, indicating that phenological effects on surface resistance are important. We also compared the simulated λE of different ecosystem types under meteorological conditions at one site. Values of λE varied between 15% and 38% of the net radiation in the simulations with mean ecosystem parameters. In general, the simulations suggest that λE is higher from forested ecosystems than from grasslands, wetlands or tundra-type ecosystems. Forests showed usually a tighter stomatal control of λE as indicated by a pronounced sensitivity of surface resistance to atmospheric vapor pressure deficit. Nevertheless, the surface resistance of forests was lower than for open vegetation types including wetlands. Tundra and wetlands had higher surface resistances, which were less sensitive to vapor pressure deficits. The results indicate that the variation in surface resistance within and between different vegetation types might play a significant role in energy exchange between terrestrial ecosystems and atmosphere. These results suggest the need to take into account vegetation type and phenology in energy exchange modeling.
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    Marine viruses: the beneficial side of a threat (2014)
    Springer
    In:  EPIC3Applied Biochemistry and Biotechnology, Springer, ISSN: 0273-2289
    Details
    Publication Date: 2014-09-30
    Description: Marine viruses are ubiquitous, extremely diverse, and outnumber any form of life in the sea. Despite their ecological importance, viruses in marine environments have been largely ignored by the academic community, and only those that have caused substantial economic losses have received more attention. Fortunately, our current understanding on marine viruses has advanced considerably during the last decades. These advances have opened new and exciting research opportunities as several unique structural and genetic characteristics of marine viruses have shown to possess an immense potential for various biotechnological applications. Here, a condensed overview of the possibilities of using the enormous potential offered by marine viruses to develop innovative products in industries as pharmaceuticals, environmental remediation, cosmetics, material sciences, and several others, is presented. The importance of marine viruses to biotechnology should not be underestimated.
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  • 29
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    Toxic effects of lab-grade butyl rubber stoppers on aerobic methane oxidation (2015)
    Wiley
    In:  EPIC3Limnology and Oceanography: Methods, Wiley, 13(1), pp. 40-52, ISSN: 1541-5856
    Details
    Publication Date: 2015-02-10
    Description: Methods for measuring aerobic methane oxidation (MOx) rates in aquatic environments are often based on the incubation of water samples, during which the consumption of methane (CH4) is monitored. Typically, incubation vessels are sealed with butyl rubber because these elastomers are essentially impermeable for gases. We report on the potential toxicity of five different commercially available, lab-grade butyl stoppers on MOx activity in samples from marine and lacustrine environments. MOx rates in incubations sealed with non-halogenated butyl were 〉 50% lower compared to parallel incubations with halogenated butyl rubber stoppers, suggesting toxic effects associated with the use of the non-halogenated butyl type. Aqueous extracts of non-halogenated butyl rubber were contaminated with high amounts of various organic compounds including potential bactericides such as benzyltoluenes and phenylalkanes. Comparably small amounts of organic contaminants were liberated from the halogenated butyl rubber stoppers but only two halogenated stopper types were found that did not seem to leach any organics into the incubation medium. Furthermore, the non-halogenated and two types of the halogenated butyl elastomers additionally leached comparably high amounts of zinc. While the source of the apparent toxicity with the use of the non-halogenated rubber stoppers remains elusive, our results indicate that leaching of contaminants from some butyl rubber stoppers can severely interfere with the activity of MOx communities, highlighting the importance of testing rubber stoppers for their respective contamination potential. The impact of leachates from butyl rubber on the assessment of biogeochemical reaction rates other than MOx seems likely but needs to be verified.
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    Ocean Acidification and Oceanic Carbon Cycling (2014)
    Springer
    In:  EPIC3Global Environmental Change, (Handbook of Global Environmental Pollution ;1), Dordrecht ; London, Springer, 973 p., pp. 103-110, ISBN: 978-94-007-5783-7
    Details
    Publication Date: 2014-10-08
    Repository Name: EPIC Alfred Wegener Institut
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  • 31
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    Towards multi-resolution global climate modeling with ECHAM6–FESOM. Part I: model formulation and mean climate (2015)
    Springer
    In:  EPIC3Climate Dynamics, Springer, 44(3), pp. 757-780, ISSN: 0930-7575
    Details
    Publication Date: 2017-01-27
    Description: A new climate model has been developed that employs a multi-resolution dynamical core for the sea ice-ocean component. In principle, the multi-resolution approach allows one to use enhanced horizontal resolution in dynamically active regions while keeping a coarse-resolution setup otherwise. The coupled model consists of the atmospheric model ECHAM6 and the finite element sea ice-ocean model (FESOM). In this study only moderate refinement of the unstructured ocean grid is applied and the resolution varies from about 25 km in the northern North Atlantic and in the tropics to about 150 km in parts of the open ocean; the results serve as a benchmark upon which future versions that exploit the potential of variable resolution can be built. Details of the formulation of the model are given and its performance in simulating observed aspects of the mean climate is described. Overall, it is found that ECHAM6–FESOM realistically simulates many aspects of the observed climate. More specifically it is found that ECHAM6–FESOM performs at least as well as some of the most sophisticated climate models participating in the fifth phase of the Coupled Model Intercomparison Project. ECHAM6–FESOM shares substantial shortcomings with other climate models when it comes to simulating the North Atlantic circulation.
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  • 32
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    Linear Weakening of the AMOC in response to Receding Glacial Ice Sheets in CCSM3 (2014)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 41(17), pp. 6252-6258, ISSN: 0094-8276
    Details
    Publication Date: 2019-07-17
    Description: The transient response of the Atlantic Meridional Overturning Circulation (AMOC) to a deglacial ice-sheet retreat is studied using the Community Climate System Model version 3 (CCSM3), with a focus on orographic effects rather than meltwater discharge. It is found that the AMOC weakens significantly (41%) in response to the deglacial ice-sheet retreat. The AMOC weakening follows the decrease of the Northern Hemisphere ice-sheet volume linearly, with no evidence of abrupt thresholds. A wind-driven mechanism is proposed to explain the weakening of the AMOC: lowering the Northern Hemisphere ice sheets induces a northward shift of the westerlies, which causes a rapid eastward sea-ice transport and expanded sea-ice cover over the subpolar North Atlantic; this expanded sea ice insulates the ocean from heat loss and leads to suppressed deep convection and a weakened AMOC. A sea ice-ocean positive feedback could be further established between the AMOC decrease and sea-ice expansion.
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  • 33
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    Assimilating SMOS sea ice thickness into a coupled ice-ocean model using a local SEIK filter (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Oceans, Wiley, ISSN: 0148-0227
    Details
    Publication Date: 2019-07-17
    Description: The impact of assimilating sea ice thickness data derived from ESA's Soil Moisture and Ocean Salinity (SMOS) satellite together with Special Sensor Microwave Imager/Sounder (SSMIS) sea ice concentration data of the National Snow and Ice Data Center (NSIDC) in a coupled sea ice-ocean model is examined. A period of 3 months from 1 November 2011 to 31 January 2012 is selected to assess the forecast skill of the assimilation system. The 24 h forecasts and longer forecasts are based on the Massachusetts Institute of Technology general circulation model (MITgcm), and the assimilation is performed by a localized Singular Evolutive Interpolated Kalman (LSEIK) filter. For comparison, the assimilation is repeated only with the SSMIS sea ice concentrations. By running two different assimilation experiments, and comparing with the unassimilated model, independent satellite-derived data, and in situ observation, it is shown that the SMOS ice thickness assimilation leads to improved thickness forecasts. With SMOS thickness data, the sea ice concentration forecasts also agree better with observations, although this improvement is smaller.
    Repository Name: EPIC Alfred Wegener Institut
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  • 34
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    Using empirical orthogonal functions derived from remote sensing reflectance for the prediction of concentrations of phytoplankton pigments. (2014)
    Copernicus
    In:  EPIC3Ocean Science Discussions, Copernicus, 11(5), pp. 2073-2117, ISSN: 1812-0822
    Details
    Publication Date: 2014-10-14
    Description: The composition and abundance of algal pigments provide information on characteristics of a phytoplankton community in respect to its photoacclimation, overall biomass, and taxonomic composition. Particularly, these pigments play a major role in photoprotection and in the light-driven part of photosynthesis. Most phytoplankton pigments can be measured by High Performance Liquid Chromatography (HPLC) techniques to filtered water samples. This method, like others when water samples have to be analysed in the laboratory, is time consuming and therefore only a limited number of data points can be obtained. In order to receive information on phytoplankton pigment composition with a higher temporal and spatial resolution, we have developed a method to assess pigment concentrations from continuous optical measurements. The method applies an Empirical Orthogonal Function (EOF) analysis to remote sensing reflectance data derived from ship-based hyper-spectral underwater radiometric and from multispectral satellite data (using the MERIS Polymer product developed by Steinmetz et al., 2011) measured in the Eastern Tropical Atlantic. Subsequently we developed statistically linear models with measured (collocated) pigment concentrations as the response variable and EOF loadings as predictor variables. The model results, show that surface concentrations of a suite of pigments and pigment groups can be well predicted from the ship-based reflectance measurements, even when only a multi-spectral resolution is chosen (i.e. eight bands similar to those used by MERIS). Based on the MERIS reflectance data, concentrations of total and monovinyl chlorophyll a and the groups of photoprotective and photosynthetic carotenoids can be predicted with high quality. The fitted statistical model constructed on the satellite reflectance data as input was applied to one month of MERIS Polymer data to predict the concentration of those pigment groups for the whole Eastern Tropical Atlantic area. Bootstrapping explorations of cross-validation error indicate that the method can produce reliable predictions with relatively small data sets (e.g., 〈 50 collocated values of reflectance and pigment concentration). The method allows for the derivation of time series from continuous reflectance data of various pigment groups at various regions, which can be used to study variability and change of phytoplankton composition and photo-physiology.
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    Seismostratigraphy of the Siberian Sector of the Arctic Ocean and adjacent Laptev Sea Shelf (2014)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Solid Earth, Wiley, 119(7), pp. 5275-5289, ISSN: 2169-9356
    Details
    Publication Date: 2014-08-18
    Description: A new seismostratigraphic model has been established within the Arctic Ocean adjacent to the East Siberian Shelf on the basis of multichannel seismic reflection data acquired along a transect at 81°N. Ages for the sedimentary units were estimated via links to seismic lines and drill site data of the US Chukchi Shelf, the Lomonosov Ridge, and the adjacent Laptev Shelf. Two distinct seismic units were mapped throughout the area and are the constraints for dating the remaining strata. The lower marker unit, a pronounced high-amplitude reflector sequence (HARS), is the most striking stratigraphic feature over large parts of the Arctic Ocean. It indicates a strong and widespread change in deposition conditions. Probably, it developed during Oligocene times when a reorientation of Arctic Plates took place, accompanied by the gradual opening of the Fram Strait, and a widespread regression of sea level. The top of the HARS likely marks the end of Oligocene/early Miocene (23Ma). An age estimate for the base of the sequence is less clear but likely corresponds to base of Eocene (˜56Ma). The second marked unit detected on the seismic lines parallels the seafloor with a thickness of about 200ms two-way travel time (160 m). Its base is marked by a change from a partly transparent sequence with weak amplitude reflections below to a set of continuous high-amplitude reflectors above. This interface likely marks the transition to large-scale glaciation of the northern hemisphere and therefore is ascribed to the top Miocene (5.3 Ma).
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    Summer sea ice concentration changes in the Weddell Sea and their causes (2013)
    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
    Details
    Publication Date: 2019-08-16
    Repository Name: EPIC Alfred Wegener Institut
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    Transient variability of the Miocene Antarctic ice Sheet smaller than equilibrium differences (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 46(8), pp. 4288-4298, ISSN: 0094-8276
    Details
    Publication Date: 2021-02-16
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    GLODAPv2.2019 – an update of GLODAPv2 (2019)
    Copernicus
    In:  EPIC3Earth System Science Data Discussions https://doi.org/10.5194/essd-2019-66, Copernicus, pp. 1-39
    Details
    Publication Date: 2019-05-02
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  • 39
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    Reaction of a polar gravel‐spit system to atmospheric warming and glacier retreat as reflected by morphology and internal sediment geometries (South Shetland Islands, Antarctica) (2019)
    Wiley
    In:  EPIC3Earth Surface Processes and Landforms, Wiley, 44(5), pp. 1148-1162, ISSN: 0197-9337
    Details
    Publication Date: 2019-04-29
    Description: Sedimentary architecture and morphogenetic evolution of a polar bay-mouth gravel-spit system are revealed based on topographic mapping, sedimentological data, radiocarbon dating and ground-penetrating radar investigations. Data document variable rates of spit progradation in reaction to atmospheric warming synchronous to the termination of the last glacial re-advance (LGR, 0.45–0.25 ka BP), the southern hemisphere equivalent of the Little Ice Age cooling period. Results show an interruption of spit progradation that coincides with the proposed onset of accelerated isostatic rebound in reaction to glacier retreat. Spit growth resumed in the late 19th century after the rate of isostatic rebound decreased, and continues until today. The direction of modern spit progradation, however, is rotated northwards compared with the growth axis of the early post-LGR spit. This is interpreted to reflect the shift and strengthening in the regional wind field during the last century. A new concept for the interplay of polar gravel-spit progradation and glacio-isostatic adjustment is presented, allowing for the prediction of future coastal evolution in comparable polar settings.
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    Improved performance of ERA5 in Arctic gateway relative to four global atmospheric reanalyses (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 46, ISSN: 0094-8276
    Details
    Publication Date: 2019-07-10
    Description: Here we evaluate five atmospheric reanalyses in an Arctic gateway during late summer. The reanalyses include ERA5, ERA-Interim, JRA-55, CFSv2 and MERRA-2. We use observations from 50 radiosondes launched in the Fram Strait around 79-80˚N, between 25 August – 11 September 2017. Crucially, data from 27 radiosondes were not transmitted to the Global Telecommunications System (GTS), and therefore not assimilated into any reanalysis. In most reanalyses, the magnitude of wind speed and humidity errors are similar for profiles with and without data assimilation. In cases without data assimilation, correlation coefficients (R) exceed 0.88 for temperature, wind speed and specific humidity, in all reanalyses. Overall, the newly released ERA5 has higher correlation coefficients than any other reanalyses as well as smaller biases and root mean square errors, for all three variables. The largest improvements identified in ERA5 are in its representation of the wind field, and temperature profiles over warm water.
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    The budget of macrobenthic reworked organic carbon ‐ a modelling case study of the North Sea (2019)
    Wiley
    In:  EPIC3Journal of Geophysical Research: Biogeosciences, Wiley, 124, pp. 1446-1471, ISSN: 2169-8961
    Details
    Publication Date: 2019-08-13
    Description: The importance of macrobenthos in benthic‐pelagic coupling and early diagenesis of organic carbon (OC) has long been recognized but has not been quantified at a regional scale. By using the southern North Sea as an exemplary area we present a modelling attempt to quantify the budget of total organic carbon (TOC) reworked by macrobenthos in seafloor surface sediments. Vertical profiles in sediments collected in the field indicate a significant but nonlinear correlation between TOC and macrobenthic biomass. A mechanistic model is used to resolve the bi‐directional interaction between TOC and macrobenthos. A novelty of this model is that bioturbation is resolved dynamically depending on variations in local food resource and macrobenthic biomass. The model is coupled to 3D hydrodynamic‐biogeochemical simulations to hindcast the mutual dependence between sedimentary TOC and macrobenthos from 1948 to 2015. Agreement with field data reveals a satisfactory model performance. Our simulations show that the preservation of TOC in the North Sea sediments is not only determined by pelagic conditions (hydrodynamic regime and primary production) but also by the vertical distribution of TOC, bioturbation intensity, and the vertical positioning of macrobenthos. Macrobenthos annually ingest 20%–35% and in addition vertically diffuse 11%–22% of the total budget of TOC in the upper‐most 30 cm sediments in the southern North Sea. This result indicates a central role of benthic animals in modulating the OC cycling at the sediment‐water interface of continental margins.
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    East Pacific Rise Core PS75/059‐2: Glacial‐to‐Deglacial Stratigraphy Revisited (2019)
    Wiley
    In:  EPIC3Paleoceanography and Paleoclimatology, Wiley, 34, pp. 432-435
    Details
    Publication Date: 2019-06-23
    Description: Age control and paleoceanographic evidence of marine sediment records might be challenged if authors solely build their stratigraphy on visual correlation to apparently well‐dated records from the same ocean basin, using, for example, highly resolved X‐ray fluorescence‐based element‐count records and correlation tools such as AnalySeries. While per se perfectly reasonable, this approach bears the risk of missing stratigraphic gaps in the sedimentary record and thus might result in imprecise and/or flawed interpretations. Here we present a unique series of 14 planktic 14C ages from a 7‐cm section of East Pacific Rise core PS75/059‐2. The ages suggest a 14‐ky‐long period of low‐to‐zero deposition during Last Glacial Maximum, mainly marked by continuous redistribution of winnowed foraminifers, probably the result of enhanced bottom currents, moreover, by some bioturbational mixing. On the basis of this data we demonstrate the impact of the hiatus on a South Pacific transect of apparent benthic ventilation ages (ΔΔ14C values) and their meaning for estimates of CO2 stored in Last Glacial Maximum Pacific deep waters.
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    Variability of Winter Snow Properties on Different Spatial Scales in the Weddell Sea (2018)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Oceans, Wiley, 123(12), pp. 8862-8876, ISSN: 0148-0227
    Details
    Publication Date: 2019-01-25
    Description: The snow cover on Antarctic sea ice persists during most of the year, contributing significantly to the sea ice mass budget due to comprehensive seasonal transition processes within the snowpack as well as at the snow/ice interface. Consequently, snow on sea ice varies not only in depth but also in particular in its physical characteristics such as snow density and stratigraphy. In order to quantify the heterogeneous nature of the Antarctic snowpack on different spatial scales, that is, small (〈10 m), floe‐size (1‐2 km), and regional (seasonal/perennial ice) scales, we present here a case study of snow analyses in the Weddell Sea in austral winter 2013. The resulting high variability of snow parameters in the basal snow layer reveals the need to distinguish between seasonal and perennial ice regimes, when retrieving, for example, snow depth using satellite microwave radiometry. Considering the full vertical snow column, a more detailed distinction of the perennial sea ice regime into, for example, more ice classes is suggested in order to represent the high variability range. For the internal snowpack variability, however, we identify the grain size variability as the main driver, while snow density variations can be neglected. Moving from regional to floe‐size scales, a similar variability range of the studied snow properties is found, suggesting that a large number of snow samples on a few floes is more crucial than covering a large region with fewer floe‐scale measurements. The spatiotemporally heterogeneous variability in snow accumulation, redistribution, and metamorphism is, however, too large to upscale the given findings beyond regional scale.
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    Impact of Weddell Sea shelf progradation on Antarctic bottom water formation during the Miocene (2017)
    Wiley
    In:  EPIC3Paleoceanography, Wiley, 32, pp. 304-317, ISSN: 0883-8305
    Details
    Publication Date: 2017-06-12
    Repository Name: EPIC Alfred Wegener Institut
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  • 45
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    Sub-seasonal thaw slump mass wasting is not consistently energy limited at the landscape scale (2017)
    Copernicus
    In:  EPIC3The Cryosphere Discussions, Copernicus, 2017, pp. 1-24
    Details
    Publication Date: 2017-08-30
    Description: Predicting future thaw slump activity requires a sound understanding of the atmospheric drivers and geomorphic controls on mass wasting across a range of time scales. On sub-seasonal time scales, sparse measurements indicate that mass wasting at active slumps is often limited by the energy available for melting ground ice, but other factors such as rainfall or the formation of an insulating veneer may also be relevant. To study the sub-seasonal drivers, we derive topographic changes from single-pass radar interferometric data acquired by the TanDEM-X satellite (12 m resolution). The high vertical precision (around 30 cm), frequent observations (11 days) and large coverage (5000 km2) allow us to track volume losses as drivers such as the available energy change during summer in two study regions. We find that thaw slumps in the Tuktoyaktuk coastlands, Canada, are not energy limited in June, as they undergo limited mass wasting (height loss of around 0 cm/day) despite the ample available energy, indicating the widespread presence of an insulating snow or debris veneer. Later in summer, height losses generally increase (around 3 cm/day), but they do so in distinct ways. For many slumps, mass wasting tracks the available energy, a temporal pattern that is also observed at coastal yedoma cliffs on the Bykovsky Peninsula, Russia. However, the other two common temporal trajectories are asynchronous with the available energy, as they track strong precipitation events or show a sudden speed-up in late August, respectively. The observed temporal patterns are poorly related to slump characteristics like the slump area. The contrasting temporal behaviour of nearby thaw slumps highlights the importance of complex local and temporally varying controls on mass wasting.
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    Circulation in the northwest Laptev Sea in the eastern Arctic Ocean: Crossroads between Siberian River water, Atlantic water and polynya-formed dense water (2017)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Oceans, Wiley, 122, pp. 1-18, ISSN: 0148-0227
    Details
    Publication Date: 2017-09-13
    Description: This paper investigates new observations from the poorly understood region between the Kara and Laptev Seas in the Eastern Arctic Ocean. We discuss relevant circulation features including riverine freshwater, Atlantic-derived water, and polynya-formed dense water, emphasize Vilkitsky Strait (VS) as an important Kara Sea gateway, and analyze the role of the adjacent 250 km-long submarine Vilkitsky Trough (VT) for the Arctic boundary current. Expeditions in 2013 and 2014 operated closely spaced hydrographic transects and 1 year-long oceanographic mooring near VT’s southern slope, and found persistent annually averaged flow of 0.2 m s21 toward the Nansen Basin. The flow is nearly barotropic from winter through early summer and becomes surface intensified with maximum velocities of 0.35 m s21 from August to October. Thermal wind shear is maximal above the southern flank at 30 m depth, in agreement with basinward flow above VT’s southern slope. The subsurface features a steep front separating warm (–0.58C) Atlantic-derived waters in central VT from cold (〈–1.58C) shelf waters, which episodically migrates across the trough indicated by current reversals and temperature fluctuations. Shelf-transformed waters dominate above VT’s slope, measuring near-freezing temperatures throughout the water column at salinities of 34–35. These dense waters are vigorously advected toward the Eurasian Basin and characterize VT as a conduit for near-freezing waters that could potentially supply the Arctic Ocean’s lower halocline, cool Atlantic water, and ventilate the deeper Arctic Ocean. Our observations from the northwest Laptev Sea highlight a topographically complex region with swift currents, several water masses, narrow fronts, polynyas, and topographically channeled storms.
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    The mechanisms behind Jakobshavn Isbræ’s acceleration and mass loss: A 3-D thermomechanical model study (2017)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 44, pp. 6252-6260, ISSN: 0094-8276
    Details
    Publication Date: 2017-09-18
    Description: The mechanisms causing widespread flow acceleration of Jakobshavn Isbræ, West Greenland, remain unclear despite an abundance of observations and modeling studies. Here we simulate the glacier's evolution from 1985 to 2016 using a three-dimensional thermomechanical ice flow model. The model captures the timing and 90% of the observed changes by forcing the calving front. Basal drag in the trough is low, and lateral drag balances the ice stream's driving stress. The calving front position is the dominant control on changes of Jakobshavn Isbræ since the ice viscosity in the shear margins instantaneously drops in response to the stress perturbation caused by calving front retreat, which allows for widespread flow acceleration. Gradual shear margin warming contributes 5 to 10% to the total acceleration. Our simulations suggest that the glacier will contribute to eustatic sea level rise at a rate comparable to or higher than at present.
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    BedMachine v3: Complete bed topography and ocean bathymetry mapping of Greenland from multi-beam echo sounding combined with mass conservation (2017)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 44(21), pp. 11051-11061
    Details
    Publication Date: 2017-12-01
    Description: Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic Water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here, we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation (MC) approach. A new 150-m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous datasets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals the total sea level potential of the Greenland Ice Sheet is 7.42±0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.
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    Quantifying manganese and nitrogen cycle coupling in manganese-rich, organic carbon-starved marine sediments: Examples from the Clarion-Clipperton fracture zone (2016)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 43, ISSN: 0094-8276
    Details
    Publication Date: 2016-12-07
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  • 50
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    Zambezi continental margin: compartmentalized sediment transfer routes to the abyssal Mozambique Channel (2017)
    Springer
    In:  EPIC3Marin Geophysical Research, Springer, 38(3), pp. 227-240
    Details
    Publication Date: 2017-09-10
    Description: Sediment delivery to the abyssal regions of the oceans is an integral process in the source to sink cycle of material derived from adjacent continents and islands. The Zambezi River, the largest in southern Africa, delivers vast amounts of material to the inner continental shelf of central Mozambique. The aim of this contribution is to better constrain sediment transport pathways to the abyssal plains using the latest, regional, high-resolution multibeam bathymetry data available, taking into account the effects of bottom water circulation, antecedent basin morphology and sea-level change. Results show that sediment transport and delivery to the abyssal plains is partitioned into three distinct domains; southern, central and northern. Sediment partitioning is primarily controlled by changes in continental shelf and shelf-break morphology under the influence of a clockwise rotating shelf circulation system. However, changes in sealevel have an overarching control on sediment delivery to particular domains. During highstand conditions, such as today, limited sediment delivery to the submarine Zambezi Valley and Channel is proposed, with increased sediment delivery to the deepwater basin being envisaged during regression and lowstand conditions. However, there is a pronounced along-strike variation in sediment transport during the sea-level cycle due to changes in the width, depth and orientation of the shelf. This combination of features outlines a sequence stratigraphic concept not generally considered in the strike-aligned shelf-slope-abyssal continuum.
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    A simulation of small to giant Antarctic iceberg evolution: Differential impact on climatology estimates (2017)
    Wiley
    In:  EPIC3Journal of Geophysical Research: Oceans, Wiley, ISSN: 21699275
    Details
    Publication Date: 2017-05-04
    Description: We present a simulation of Antarctic iceberg drift and melting that includes small, medium-sized, and giant tabular icebergs with a realistic size distribution. For the first time, an iceberg model is initialized with a set of nearly 7000 observed iceberg positions and sizes around Antarctica. The study highlights the necessity to account for larger and giant icebergs in order to obtain accurate melt climatologies. We simulate drift and lateral melt using iceberg-draft averaged ocean currents, temperature, and salinity. A new basal melting scheme, originally applied in ice shelf melting studies, uses in situ temperature, salinity, and relative velocities at an iceberg's bottom. Climatology estimates of Antarctic iceberg melting based on simulations of small (≤ 2.2 km), 'small-to-medium'-sized (≤ 10 km), and small-to-giant icebergs (including icebergs 〉 10 km) exhibit differential characteristics: successive inclusion of larger icebergs leads to a reduced seasonality of the iceberg meltwater flux and a shift of the mass input to the area north of 58 °S, while less meltwater is released into the coastal areas. This suggests that estimates of meltwater input solely based on the simulation of small icebergs introduce a systematic meridional bias; they underestimate the northward mass transport and are, thus, closer to the rather crude treatment of iceberg melting as coastal runoff in models without an interactive iceberg model. Future ocean simulations will benefit from the improved meridional distribution of iceberg melt, especially in climate change scenarios where the impact of iceberg melt is likely to increase due to increased calving from the Antarctic ice sheet.
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    Satellite-observed drop of Arctic sea ice growth in winter 2015–2016 (2017)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, ISSN: 0094-8276
    Details
    Publication Date: 2017-09-25
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    Oxygenated volatile organic carbon in the western Pacific convective centre: ocean cycling, air–sea gas exchange and atmospheric transport. (2017)
    Copernicus
    In:  EPIC3Atmos. Chem. Phys. Discuss., Copernicus, acp-20, ISSN: 1680-7375
    Details
    Publication Date: 2017-11-06
    Description: A suite of oxygenated volatile organic compounds (OVOCs – acetaldehyde, acetone, propanal, butanal and butanone) were measured concurrently in the surface water and atmosphere of the South China Sea and Sulu Sea in November 2011. A strong correlation was observed between all OVOC concentrations in the surface seawater along the entire cruise track, except for acetaldehyde, suggesting similar sources and sinks in the surface ocean. Additionally, several phytoplankton groups, such as haptophytes or pelagophytes, were also correlated to all OVOCs indicating that phytoplankton may be an important source for marine OVOCs in the South China and Sulu Seas. Humic and protein like fluorescent dissolved organic matter (FDOM) components seemed to be additional precursors for butanone and acetaldehyde. The atmospheric OVOC mixing ratios were relative high compared with literature values, suggesting the coastal region of North Borneo as a local hot spot for atmospheric OVOCs. The flux of atmospheric OVOCs was largely into the ocean for all 5 gases, with a few important exceptions near the coast of Borneo. The calculated amount of OVOCs entrained into the ocean seemed to be an important source of OVOCs to the surface ocean. When the fluxes were out of the ocean, marine OVOCs were found to be enough to control the local measured OVOC distribution in the atmosphere. Based on our model calculations, at least 0.4 ppb of marine derived acetone and butanone can reach the upper troposphere, where they may have an important influence on hydrogen oxide radical formation over the western Pacific Ocean.
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    Animal Forests in the Chilean Fjords: Discoveries, Perspectives and Threats in Shallow and Deep Waters (2016)
    Springer
    In:  EPIC3Marine Animal Forests, Marine Animal Forests, Switzerland, Springer, 35 p., ISBN: 978-3-319-17001-5
    Details
    Publication Date: 2017-09-26
    Description: The Chilean fjord region, situated between 42 and 56 °S, forms one of the most ragged shorelines and belongs to the ecologically and biogeographically least understood marine regions of the world. A labyrinth of fjords, channels, and islands extends over 240,000 km2 and creates a coastline of more than 80,000 km. Due to strong abiotic gradients, numerous habitats are created, which are further diversified by temporal dynamics (tidal cycle, seasonal changes in precipitation, temperature, radiation, etc.). The region is a biodiversity hotspot hosting unique and fragile ecosystems. Among the species living here, several are species forming habitats in the ecosystem. These organisms can reach high densities conforming the so-called marine animal forests. Examples are marine animal forests dominated by cold-water stony corals, gorgonians, hydrocorals, brachiopods, polychaetes, giant barnacles, sponges, and ascidians. Many of these communities have been discov- ered only recently. There is also a singular characteristic in this area: exceptionally low pH levels of the waters of Patagonian fjords provide the opportunity to study calcifying organisms in an environment with pH conditions in the same range as the ones predicted by the IPCC for the world oceans in 2100. Despite the scarce ecological and biogeographical knowledge of this area, it encounters an unparalleled economic development including high-impact industry-scale salmonid farming, ambitious infrastructure and industrialization projects, and increasing extractive activities. Baseline research on the abiotic and biotic environment of the region is needed to reach sustainability in the use of the marine resources. Management plans including the establishment of marine protected areas to preserve benthic diversity and ecosystem services are urgently needed.
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    The Extrapolar SWIFT model (version 1.0): fast stratospheric ozone chemistry for global climate models (2017)
    Copernicus
    In:  EPIC3Geoscientific Model Development, Copernicus, 11, pp. 753-769
    Details
    Publication Date: 2018-03-28
    Description: The Extrapolar SWIFT model is a fast ozone chemistry scheme for interactive calculation of the extrapolar stratospheric ozone layer in coupled general circulation models (GCMs). In contrast to the widely used prescribed ozone, the SWIFT ozone layer interacts with the model dynamics and can respond to atmospheric variability or climatological trends. The Extrapolar SWIFT model employs a repro-modelling approach, where algebraic functions are used to approximate the numerical output of a full stratospheric chemistry and transport model (ATLAS). The full model solves a coupled chemical differential equations system with 55 initial and boundary conditions (mixing ratio of various chemical species and atmospheric parameters). Hence the rate of change of ozone over 24  h is a function of 55 variables. Using covariances between these variables, we can find linear combinations in order to reduce the parameter space to the following nine basic variables: latitude, pressure altitude, temperature, local ozone column, mixing ratio of ozone and of the ozone depleting families (Cly, Bry, NOy and HOy). We will show that these 9 variables are sufficient to characterize the rate of change of ozone. An automated procedure fits a polynomial function of fourth degree to the rate of change of ozone obtained from several simulations with the ATLAS model. One polynomial function is determined per month which yields the rate of change of ozone over 24 h. A key aspect for the robustness of the Extrapolar SWIFT model is to include a wide range of stratospheric variability in the numerical output of the ATLAS model, also covering atmospheric states that will occur in a future climate (e.g. temperature and meridional circulation changes or reduction of stratospheric chlorine loading). For validation purposes, the Extrapolar SWIFT model has been integrated into the ATLAS model replacing the full stratospheric chemistry scheme. Simulations with SWIFT in ATLAS have proven that the systematic error is small and does not accumulate during the course of a simulation. In the context of a 10 year simulation, the ozone layer, simulated by SWIFT, shows a stable annual cycle, with inter-annual variations comparable to the ATLAS model. The application of Extrapolar SWIFT requires the evaluation of polynomial functions with 30–100 terms. Nowadays, computers can calculate such polynomial functions at thousands of model grid points in seconds. SWIFT provides the desired numerical efficiency and computes the ozone layer 104 times faster than the chemistry scheme in the ATLAS CTM.
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    On the role of dust-deposited lithogenic particles for iron cycling in the tropical and subtropical Atlantic (2017)
    Wiley
    In:  EPIC3Global Biogeochemical Cycles, Wiley, ISSN: 0886-6236
    Details
    Publication Date: 2017-10-27
    Repository Name: EPIC Alfred Wegener Institut
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    Observing the impact of Calbuco volcanic aerosols on South Polar ozone depletion in 2015 (2017)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Atmospheres, Wiley, ISSN: 0148-0227
    Details
    Publication Date: 2019-12-03
    Description: The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April, and a record-large Antarctic ozone hole in October and November. Here, we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observations and an earth system model. We analyze ozonesondes, as well as data from the Microwave Limb Sounder. We employ the Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model (CESM1(WACCM)) in a specified dynamics setup, which includes calculations of volcanic effects. The Cloud Aerosol Lidar with Orthogonal Polarization data indicate enhanced volcanic liquid sulfate 532 nm backscatter values as far poleward as 68°S during October and November (in broad agreement with WACCM). Comparison of the location of the enhanced aerosols to ozone data supports the view that aerosols played a major role in increasing the ozone hole size, especially at pressure levels between 150 and 100 hPa. Ozonesonde vertical ozone profiles from the sites of Syowa, South Pole, and Neumayer, display the lowest individual October or November measurements at 150 hPa since the 1991 Mt. Pinatubo eruption period, with Davis showing similarly low values, but no available 1990s data. The analysis suggests that under the cold conditions ideal for ozone depletion, stratospheric volcanic aerosol particles from the moderate-magnitude eruption of Calbuco in 2015 greatly enhanced austral ozone depletion, particularly at 55–68°S, where liquid binary sulfate aerosols have a large influence on ozone concentrations.
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    Winter sea ice export from the Laptev Sea preconditions the local summer sea ice cover and fast ice decay (2017)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 11(5), pp. 2383-2391
    Details
    Publication Date: 2017-10-24
    Description: Ice retreat in the eastern Eurasian Arctic is a consequence of atmospheric and oceanic processes and regional feedback mechanisms acting on the ice cover, both in winter and summer. A correct representation of these processes in numerical models is important, since it will improve predictions of sea ice anomalies along the Northeast Passage and beyond. In this study, we highlight the importance of winter ice dynamics for local summer sea ice anomalies in thickness, volume and extent. By means of airborne sea ice thickness surveys made over pack ice areas in the south-eastern Laptev Sea, we show that years of offshore-directed sea ice transport have a thinning effect on the late-winter sea ice cover. To confirm the preconditioning effect of enhanced offshore advection in late winter on the summer sea ice cover, we perform a sensitivity study using a numerical model. Results verify that the preconditioning effect plays a bigger role for the regional ice extent. Furthermore, they indicate an increase in volume export from the Laptev Sea as a consequence of enhanced offshore advection, which has far-reaching consequences for the entire Arctic sea ice mass balance. Moreover we show that ice dynamics in winter not only preconditions local summer ice extent, but also accelerate fast-ice decay.
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    Discussion of Different Model Approaches for the Flow Behavior of Ice (2016)
    Wiley
    In:  EPIC3Proceedings in Applied Mathematics and Mechanics, Wiley, 16(1), pp. 313-314, ISSN: 16177061
    Details
    Publication Date: 2017-11-13
    Description: Ice of Antarctic ice shelves is assumed to behave on long-term as an incompressible viscous fluid, which is dominated on short time scales by the elastic response. Hence, a viscoelastic material model is required. The thermodynamic pressure is treated differently in elastic and viscous models. For small deformations, the elastic isometric stress for ν → 0.5 gives similar results to those solving for pressure in an incompressible laminar flow model. A viscous model, in which the thermodynamic pressure is approximated by an elastic isometric stress, can be easily extended to viscoelasticity.
    Repository Name: EPIC Alfred Wegener Institut
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    Aquatische Ökosysteme: Nordsee, Wattenmeer, Elbeästuar und Ostsee (2017)
    Springer
    In:  EPIC3Hamburger Klimabericht – Wissen über Klima, Klimawandel und Auswirkungen in Hamburg und Norddeutschland, Springer, 311 p., pp. 90-107, ISBN: 978-3-662-55378-7
    Details
    Publication Date: 2017-11-09
    Repository Name: EPIC Alfred Wegener Institut
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    Multi-model evidence for an atmospheric circulation response to Arctic sea ice loss in the CMIP5 future projections (2018)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, ISSN: 0094-8276
    Details
    Publication Date: 2018-01-09
    Repository Name: EPIC Alfred Wegener Institut
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    Increasing frequency and duration of Arctic winter warming events (2017)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 44(13), pp. 6974-6983, ISSN: 0094-8276
    Details
    Publication Date: 2018-01-11
    Description: Near-surface air temperatures close to 0°C were observed in situ over sea ice in the central Arctic during the last three winter seasons. Here we use in situ winter (December–March) temperature observations, such as those from Soviet North Pole drifting stations and ocean buoys, to determine how common Arctic winter warming events are. Observations of winter warming events exist over most of the Arctic Basin. Temperatures exceeding -5°C were observed during 〉30% of winters from 1954 to 2010 by North Pole drifting stations or ocean buoys. Using the ERA-Interim record (1979–2016), we show that the North Pole (NP) region typically experiences 10 warming events (T2m 〉 10°C) per winter, compared with only five in the Pacific Central Arctic (PCA). There is a positive trend in the overall duration of winter warming events for both the NP region (4.25 days/decade) and PCA (1.16 days/decade), due to an increased number of events of longer duration.
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    Tritium records to trace stratospheric moisture inputs in Antarctica (2018)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Atmospheres, Wiley, ISSN: 0148-0227
    Details
    Publication Date: 2018-03-19
    Repository Name: EPIC Alfred Wegener Institut
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    Ballasting by cryogenic gypsum enhances carbon export in a Phaeocystis under-ice bloom (2018)
    Springer
    In:  EPIC3Scientific Reports, Springer, 8(7703)
    Details
    Publication Date: 2019-02-14
    Description: Mineral ballasting enhances carbon export from the surface to the deep ocean; however, little is known about the role of this process in the ice-covered Arctic Ocean. Here, we propose gypsum ballasting as a new mechanism that likely facilitated enhanced vertical carbon export from an under-ice phytoplankton bloom dominated by the haptophyte Phaeocystis. In the spring 2015 abundant gypsum crystals embedded in Phaeocystis aggregates were collected throughout the water column and on the sea floor at a depth below 2 km. Model predictions supported by isotopic signatures indicate that 2.7 g m−2 gypsum crystals were formed in sea ice at temperatures below −6.5°C and released into the water column during sea ice melting. Our finding indicates that sea ice derived (cryogenic) gypsum is stable enough to survive export to the deep ocean and serves as an effective ballast mineral. Our findings also suggest a potentially important and previously unknown role of Phaeocystis in deep carbon export due to cryogenic gypsum ballasting. The rapidly changing Arctic sea ice regime might favour this gypsum gravity chute with potential consequences for carbon export and food partitioning between pelagic and benthic ecosystems.
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    Deglacial Subarctic Pacific Oxygenation Changes: Causes and Links to Northern Hemisphere Climate (2018)
    Copernicus
    In:  EPIC3European Geosciences Union EGU General Assembly, Vienna, Austria, 2018-04-08-2018-04-13Copernicus
    Details
    Publication Date: 2018-06-18
    Description: We use a comprehensive suite of partially laminated high-resolution sediment cores from the Bering Sea, covering a depth transect from 1100 m to 2700 m to study deglacial surface ocean warming patterns, associated changes in biological productivity, oxygen minimum zone dynamics and continent-ocean links through Yukon river runoff. We apply a combination of planktic and benthic isotopes, x-ray fluorescence (XRF)-derived ele- mental ratios and a multi-proxy assessment of changes in upper ocean temperatures. Severe oxygen depletions occurred during the Bølling/Allerød (B/A) and early Holocene, which is in accordance with other locations in the North Pacific, especially the Alaska margin. Detailed analysis of the timing of lamination occurrence between the different sediment cores revealed that the onset of severe anoxia at the beginning of the B/A and early Holocene is a near-synchronous event, while the disappearance of laminations is a diachronic process. The deglacial Oxygen Minimum Zone(OMZ) strengthening is mainly driven by increased export production, visible in XRF-derived elemental ratios, and corresponding high accumulation rates of biogenic components. The export production in turn is a response to rising sea surface temperatures, decreased sea ice cover and increased thermal stratification, while a major nutrient source was the eastern continental shelf, which was flooded during the deglacial global sea level rise. It is discussed controversially whether oxygenation variations in the deglacial subarctic Pacific were coupled to changes in mid-depth water chemistry, or rather a response to physical processes like deep-intermediate ocean or mixed layer warming, or stratification changes. However, knowledge of the driving forcing mechanism for OMZ strengthening is of particular importance, as these are tightly coupled to the regional marine carbon budget, e.g. via the strength and efficiency of the biological pump. Here, our laminated sediments provided the opportunity to study ocean dynamics in exceptional detail, possible on decadal to annual timescales. Due to the correlation patterns of our records to the NGRIP oxygen isotope record through layer counts we presume that (i) the presence of laminations is tightly coupled to submillennial, short-term warm phases, especially during the Bølling-Allerød (B/A), (ii) that the laminations represent annual layered sediments (varves). The latter point in conjunction with our geochemical proxies strongly supports an atmospheric teleconnection between SE Asia, the North Atlantic and the North Pacific, with observed changes in mid-depth ocean dynamics occurring on fast, nearly decadal timescales. Thus, the Bering Sea OMZ is a highly sensitive system reacting almost instantaneously to small temperature changes and therefore has the potential to influence the global carbon budget on short timescales, in particular during episodes of rapidly warming climate.
    Repository Name: EPIC Alfred Wegener Institut
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    Arctic Sea Ice Decline Significantly Contributed to the Unprecedented Liquid Freshwater Accumulation in the Beaufort Gyre of the Arctic Ocean (2018)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 45, pp. 4956-4964, ISSN: 0094-8276
    Details
    Publication Date: 2018-06-19
    Description: The Beaufort Gyre (BG) is the largest liquid freshwater reservoir of the Arctic Ocean. The liquid freshwater content (FWC) significantly increased in the BG in the 2000s during an anticyclonic wind regime and remained at a high level despite a transition to a more cyclonic state in the early 2010s. It is not well understood to what extent the rapid sea ice decline during this period has modified the trend and variability of the BG liquid FWC in the past decade. Our numerical simulations show that about 50% of the liquid freshwater accumulated in the BG in the 2000s can be explained by the sea ice decline caused by the Arctic atmospheric warming. Among this part of the FWC increase, 60% can be attributed to surface freshening associated with the reduction of the net sea ice thermodynamic growth rate, and 40% to changes in ocean circulation, which makes freshwater more accessible to the BG for storage. Thus, the rapid increase of the BG FWC in the 2000s was due to the concurrence of the anticyclonic wind regime and the high freshwater availability. We also find that if the Arctic sea ice had not declined, the liquid FWC in the BG would have shown a stronger decreasing tendency at the beginning of the 2010s owing to the cyclonic wind regime. From our results we argue that changes in sea ice conditions should be adequately taken into account when it comes to understanding and predicting variations of BG liquid FWC in a changing climate.
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    Oxygen fluxes beneath Arctic land-fast ice and pack ice: towards estimates of ice productivity (2018)
    Springer
    In:  EPIC3Polar Biology, Springer, ISSN: 0722-4060
    Details
    Publication Date: 2018-06-14
    Description: Sea-ice ecosystems are among the most extensive of Earth’s habitats; yet its autotrophic and heterotrophic activities remain poorly constrained. We employed the in situ aquatic eddy-covariance (AEC) O2 flux method and laboratory incubation techniques (H14CO3−, [3H] thymidine and [3H] leucine) to assess productivity in Arctic sea-ice using different methods, in conditions ranging from land-fast ice during winter, to pack ice within the central Arctic Ocean during summer. Laboratory tracer measurements resolved rates of bacterial C demand of 0.003–0.166 mmol C m−2 day−1 and primary productivity rates of 0.008–0.125 mmol C m−2 day−1 for the different ice floes. Pack ice in the central Arctic Ocean was overall net autotrophic (0.002–0.063 mmol C m−2 day−1), whereas winter land-fast ice was net heterotrophic (− 0.155 mmol C m−2 day−1). AEC measurements resolved an uptake of O2 by the bottom-ice environment, from ~ − 2 mmol O2 m−2 day−1 under winter land-fast ice to~ − 6 mmol O2 m−2 day−1 under summer pack ice. Flux of O2-deplete meltwater and changes in water flow velocity masked potential biological-mediated activity. AEC estimates of primary productivity were only possible at one study location. Here, productivity rates of 1.3 ± 0.9 mmol O2 m−2 day−1, much larger than concurrent laboratory tracer estimates (0.03 mmol C m−2 day−1), indicate that ice algal production and its importance within the marine Arctic could be underestimated using traditional approaches. Given careful flux interpretation and with further development, the AEC technique represents a promising new tool for assessing oxygen dynamics and sea-ice productivity in ice-covered regions.
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    Terrain controls on the occurrence of coastal retrogressive thaw slumps along the Yukon Coast, Canada (2017)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Earth Surface, Wiley, 122, pp. 1619-1634, ISSN: 0148-0227
    Details
    Publication Date: 2018-08-30
    Description: Retrogressive thaw slumps (RTSs) are among the most active landforms in the Arctic; their number has increased significantly over the past decades. While processes initiating discrete RTSs are well identified, the major terrain controls on the development of coastal RTSs at a regional scale are not yet defined. Our research reveals the main geomorphic factors that determine the development of RTSs along a 238 km segment of the Yukon Coast, Canada. We (1) show the current extent of RTSs, (2) ascertain the factors controlling their activity and initiation, and (3) explain the spatial differences in the density and areal coverage of RTSs. We mapped and classified 287 RTSs using high-resolution satellite images acquired in 2011. We highlighted the main terrain controls over their development using univariate regression trees model. Coastal geomorphology influenced both the activity and initiation of RTSs: active RTSs and RTSs initiated after 1972 occurred primarily on terrains with slope angles greater than 3.9° and 5.9°, respectively. The density and areal coverage of RTSs were constrained by the volume and thickness of massive ice bodies. Differences in rates of coastal change along the coast did not affect the model. We infer that rates of coastal change averaged over a 39 year period are unable to reflect the complex relationship between RTSs and coastline dynamics. We emphasize the need for large-scale studies of RTSs to evaluate their impact on the ecosystem and to measure their contribution to the global carbon budget.
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    Influence of a salt plume parameterization in a coupled climate model (2018)
    Wiley
    In:  EPIC3Journal of Advances in Modeling Earth Systems, Wiley, ISSN: 1942-2466
    Details
    Publication Date: 2019-04-11
    Description: Sea ice formation is accompanied by the rejection of salt which in nature tends to be mixed vertically by the formation of convective plumes. Here we analyze the influence of a salt plume parameterization (SPP) in an atmosphere-sea ice-ocean model. Two 330 years long simulations have been conducted with the AWI Climate Model. In the reference simulation, the rejected salt in the Arctic Ocean is added to the upper-most ocean layer. This approach is commonly used in climate modelling. In another experiment, employing SPP, the rejected salt is vertically redistributed within the mixed layer based on a power law profile that mimics the penetration of salt plumes. We discuss the effects of this redistribution on the simulated mean state and on atmosphere-ocean linkages associated with the intensity of deep water formation. We find that the salt plume parametrization leads to simultaneous increase of sea ice (volume and concentration) and decrease of sea surface salinity in the Arctic. The SPP considerably alters the interplay between the atmosphere and the ocean in the Nordic Seas. The parameterization modifies the ocean ventilation; however, resulting changes in temperature and salinity largely compensate each other in terms of density so that the overturning circulation is not significantly affected.
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    Variability in Rates of Coastal Change Along the Yukon Coast, 1951 to 2015 (2018)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Earth Surface, Wiley, 123, pp. 779-800, ISSN: 0148-0227
    Details
    Publication Date: 2018-12-29
    Description: To better understand the reaction of Arctic coasts to increasing environmental pressure, coastal changes along a 210-km length of the Yukon Territory coast in north-west Canada were investigated. Shoreline positions were acquired from aerial and satellite images between 1951 and 2011. Shoreline change rates were calculated for multiple time periods along the entire coast and at six key sites. Additionally, Differential Global Positioning System (DGPS) measurements of shoreline positions from seven field sites were used to analyze coastal dynamics from 1991 to 2015 at higher spatial resolution. The whole coast has a consistent, spatially averaged mean rate of shoreline change of 0.7 ± 0.2 m/a with a general trend of decreasing erosion from west to east. Additional data from six key sites shows that the mean shoreline change rate decreased from �1.3 ± 0.8 (1950s–1970s) to �0.5 ± 0.6 m/a (1970s–1990s). This was followed by a significant increase in shoreline change to �1.3 ± 0.3 m/a in the 1990s to 2011. This increase is confirmed by DGPS measurements that indicate increased erosion rates at local rates up to �8.9 m/a since 2006. Ground surveys and observations with remote sensing data indicate that the current rate of shoreline retreat along some parts of the Yukon coast is higher than at any time before in the 64-year-long observation record. Enhanced availability of material in turn might favor the buildup of gravel features, which have been growing in extent throughout the last six decades.
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    Radiative impact of an extreme Arctic biomass-burning event (2018)
    Copernicus
    In:  EPIC3Atmos. Chem. Phys., Copernicus, 18, pp. 8829-8848
    Details
    Publication Date: 2020-03-05
    Description: The aim of the presented study was to investigate the impact on the radiation budget of a biomass-burning plume, transported from Alaska to the High Arctic region of Ny-Ålesund, Svalbard, in early July 2015. Since the mean aerosol optical depth increased by the factor of 10 above the average summer background values, this large aerosol load event is considered particularly exceptional in the last 25 years. In situ data with hygroscopic growth equations, as well as remote sensing measurements as inputs to radiative transfer models, were used, in order to estimate biases associated with (i) hygroscopicity, (ii) variability of single-scattering albedo profiles, and (iii) plane-parallel closure of the modelled atmosphere. A chemical weather model with satellite-derived biomass-burning emissions was applied to interpret the transport and transformation pathways. The provided MODTRAN radiative transfer model (RTM) simulations for the smoke event (14:00 9 July–11:30 11 July) resulted in a mean aerosol direct radiative forcing at the levels of −78.9 and −47.0 W m ^-2 at the surface and at the top of the atmosphere, respectively, for the mean value of aerosol optical depth equal to 0.64 at 550 nm. This corresponded to the average clear-sky direct radiative forcing of −43.3 W/m ^2, estimated by radiometer and model simulations at the surface. Ultimately, uncertainty associated with the plane-parallel atmosphere approximation altered results by about 2 W m^−2. Furthermore, model-derived aerosol direct radiative forcing efficiency reached on average −126 W m^−2/τ550 and −71 W^m−2/τ550 at the surface and at the top of the atmosphere, respectively. The heating rate, estimated at up to 1.8 K day^−1 inside the biomass-burning plume, implied vertical mixing with turbulent kinetic energy of 0.3 m^2s^−2
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    A New Bathymetry for the Southeastern Filchner-Ronne Ice Shelf: Implications for Modern Oceanographic Processes and Glacial History (2018)
    Wiley
    In:  EPIC3Journal of Geophysical Research: Oceans, Wiley, 123(7), pp. 4610-4623, ISSN: 21699275
    Details
    Publication Date: 2018-09-24
    Description: The Filchner‐Ronne Ice Shelf, the ocean cavity beneath it, and the Weddell Sea that bounds it, form an important part of the global climate system by modulating ice discharge from the Antarctic Ice Sheet and producing cold dense water masses that feed the global thermohaline circulation. A prerequisite for modeling the ice sheet and oceanographic processes within the cavity is an accurate knowledge of the sub‐ice sheet bedrock elevation, but beneath the ice shelf where airborne radar cannot penetrate, bathymetric data are sparse. This paper presents new seismic point measurements of cavity geometry from a particularly poorly sampled region south of Berkner Island that connects the Filchner and Ronne ice shelves. An updated bathymetric grid formed by combining the new data with existing data sets reveals several new features. In particular, a sill running between Berkner Island and the mainland could alter ocean circulation within the cavity and change our understanding of paleo‐ice stream flow in the region. Also revealed are deep troughs near the grounding lines of Foundation and Support Force ice streams, which provide access for seawater with melting potential. Running an ocean tidal model with the new bathymetry reveals large differences in tidal current velocities, both within the new gridded region and further afield, potentially affecting sub‐ice shelf melt rates.
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    In-situ mechanical weakness of subducting sediments beneath a plate boundary décollement in the Nankai Trough (2018)
    Springer
    In:  EPIC3Progress in Earth and Planetary Science, Springer
    Details
    Publication Date: 2018-11-12
    Description: The study investigates the in-situ strength of sediments across a plate boundary décollement using drilling parameters recorded when a 1180-m-deep borehole was established during International Ocean Discovery Program (IODP)Expedition 370, Temperature-Limit of the Deep Biosphere off Muroto (T-Limit). Information of the in-situ strength of the shallow portion in/around a plate boundary fault zone is critical for understanding the development of accretionary prisms and of the décollement itself. Studies using seismic reflection surveys and scientific ocean drillings have recently revealed the existence of high pore pressure zones around frontal accretionary prisms, which may reduce the effective strength of the sediments. A direct measurement of in-situ strength by experiments, however, has not been executed due to the difficulty in estimating in-situ stress conditions. In this study, we derived a depth profile for the in-situ strength of a frontal accretionary prism across a décollement from drilling parameters using the recently established equivalent strength (EST) method. At site C0023, the toe of the accretionary prism area off Cape Muroto, Japan, the EST gradually increases with depth but undergoes a sudden change at ~ 800 mbsf, corresponding to the top of the subducting sediment. At this depth, directly below the décollement zone, the EST decreases from ~ 10 to 2 MPa, with a change in the baseline. This mechanically weak zone in the subducting sediments extends over 250 m (~ 800–1050 mbsf), corresponding to the zone where the fluid influx was discovered, and high-fluid pressure was suggested by previous seismic imaging observations. Although the origin of the fluids or absolute values of the strength remain unclear, our investigations support previous studies suggesting that elevated pore pressure beneath the décollement weakens the subducting sediments.
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    Spatial distribution and habitat preferences of demersal fish assemblages in the southeastern Weddell Sea (Southern Ocean) (2019)
    Springer
    In:  EPIC3Polar Biology, Springer, ISSN: 0722-4060
    Details
    Publication Date: 2019-04-10
    Description: Our knowledge on distribution, habitats and behavior of Southern Ocean fishes living at water depths beyond scuba-diving limits is still sparse, as it is difficult to obtain quantitative data on these aspects of their biology. Here, we report the results of an analysis of seabed images to investigate species composition, behavior, spatial distribution and preferred habitats of demersal fish assemblages in the southern Weddell Sea. Our study was based on a total of 2736 high-resolution images, covering a total seabed area of 11,317 m2, which were taken at 13 stations at water depths between 200 and 750 m. Fish were found in 380 images. A total of 379 notothenioid specimens were recorded, representing four families (Nototheniidae, Artedidraconidae, Bathydraconidae, Channichthyidae), 17 genera and 25 species. Nototheniidae was the most speciose fam- ily, including benthic species (Trematomus spp.) and the pelagic species Pleuragramma antarctica, which was occasionally recorded in dense shoals. Bathydraconids ranked second with six species, followed by artedidraconids and channichthyids, both with five species. Most abundant species were Trematomus scotti and T. lepidorhinus among nototheniids, and Dol- loidraco longedorsalis and Pagetopsis maculatus among artedidraconids and channichthyids, respectively. Both T. lepi- dorhinus and P. maculatus preferred seabed habitats characterized by biogenous debris and rich epibenthic fauna, whereas T. scotti and D. longedorsalis were frequently seen resting on fine sediments and scattered gravel. Several fish species were recorded to make use of the three-dimensional structure formed by epibenthic foundation species, like sponges, for perching or hiding inside. Nesting behavior was observed, frequently in association with dropstones, in species from various families, including Channichthyidae (Chaenodraco wilsoni and Pagetopsis macropterus) and Bathydraconidae (Cygnodraco mawsoni).
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    Challenges associated with the climatic interpretation of water stable isotope records from a highly resolved firn core from Adélie Land, coastal Antarctica (2019)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 13(4), pp. 1297-1324, ISSN: 1994-0424
    Details
    Publication Date: 2020-01-21
    Description: A new 21.3m firn core was drilled in 2015 at a coastal Antarctic high-accumulation site in Adélie Land (66.78◦ S; 139.56◦ E, 602 m a.s.l.), named Terre Adélie 192A (TA192A). The mean isotopic values (−19.3 ‰ ± 3.1 ‰ for δ18O and 5.4 ‰±2.2 ‰ for deuterium excess) are consistent with other coastal Antarctic values. No significant isotope–temperature relationship can be evidenced at any timescale. This rules out a simple interpretation in terms of local temperature. An observed asymmetry in the δ18O seasonal cycle may be explained by the precipitation of air masses coming from the eastern and western sectors in autumn and winter, recorded in the d-excess signal showing outstanding values in austral spring versus autumn. Significant positive trends are observed in the annual d-excess record and local sea ice extent (135–145◦ E) over the period 1998–2014. However, process studies focusing on resulting isotopic compositions and particularly the deuterium excess–δ18O relationship, evidenced as a potential fingerprint of moisture origins, as well as the collection of more isotopic measurements in Adélie Land are needed for an accurate interpretation of our signals.
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    Algal Export in the Arctic Ocean in Times of Global Warming (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, ISSN: 0094-8276
    Details
    Publication Date: 2019-06-16
    Description: Satellite‐derived data suggest an increase in annual primary production following the loss of summer sea ice in the Arctic Ocean. The scarcity of field data to corroborate this enhanced algal production incited a collaborative project combining six annual cycles of sequential sediment trap measurements obtained over a 17‐year period in the Eurasian Arctic Ocean. Here we present microalgal fluxes measured at ~200 m to reflect the bulk of algal carbon production. Ice algae contributed to a large proportion of the microalgal carbon export before complete ice melt and possible detection of their production by satellites. In the northern Laptev Sea, annual microalgal carbon fluxes were lower during the 2007 minimum ice extent than in 2006. In 2012, early snowmelt led to early microalgal carbon flux in the Nansen Basin. Hence, a change in the timing of snowmelt and ice algae release may affect productivity and export over the Arctic basins.
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    Fast EVP Solutions in a High‐Resolution Sea Ice Model (2019)
    Wiley
    In:  EPIC3Journal of Advances in Modeling Earth Systems, Wiley, ISSN: 1942-2466
    Details
    Publication Date: 2020-08-27
    Description: Sea ice dynamics determine the drift and deformation of sea ice. Nonlinear physics, usually expressed in a viscous‐plastic rheology, makes the sea ice momentum equations notoriously difficult to solve. At increasing sea ice model resolution the nonlinearities become stronger as linear kinematic features (leads) appear in the solutions. Even the standard elastic‐viscous‐plastic (EVP) solver for sea ice dynamics, which was introduced for computational efficiency, becomes computationally very expensive, when accurate solutions are required, because the numerical stability requires very short, and hence more, subcycling time steps at high resolution. Simple modifications to the EVP solver have been shown to remove the influence of the number of subcycles on the numerical stability. At low resolution appropriate solutions can be obtained with only partial convergence based on a significantly reduced number of subcycles as long as the numerical procedure is kept stable. This previous result is extended to high resolution where linear kinematic features start to appear. The computational cost can be strongly reduced in Arctic Ocean simulations with a grid spacing of 4.5 km by using modified and adaptive EVP versions because fewer subcycles are required to simulate sea ice fields with the same characteristics as with the standard EVP.
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    Asynchronous variation in the Quaternary East Asian winter monsoon associated with the tropical Pacific ENSO‐like system (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 46, ISSN: 0094-8276
    Details
    Publication Date: 2019-07-15
    Description: Quaternary East Asian winter monsoon (EAWM) evolution has long been attributed to high‐latitude Northern Hemisphere climate change. However, it cannot explain the distinct relationships of the EAWM in the northern and southern East Asian marginal sea in paleoclimatic records. Here we present an EAWM record of the northern East China Sea over the past 300 ka and a transient climate simulation with the Kiel Climate Model through the Holocene. Both proxy record and simulation suggest anticorrelated long‐term EAWM evolution between the northern East China Sea and the South China Sea. We suggest that this spatial discrepancy of EAWM can be interpreted as El Niño–Southern Oscillation (ENSO)‐like controlling, which generates cyclonic/anticyclonic wind anomalies in the northern/southern East Asian marginal sea. This research explains much of the controversy in nonorbital scale variability of Quaternary EAWM records in the East Asian marginal sea and supports a potent role of tropical forcing in East Asian winter climate change.
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    The Weddell Gyre, Southern Ocean: present knowledge and future challenges (2019)
    Wiley
    In:  EPIC3Reviews of Geophysics, Wiley, 57, ISSN: 8755-1209
    Details
    Publication Date: 2019-08-01
    Description: The Weddell Gyre (WG) is one of the main oceanographic features of the Southern Ocean south of the Antarctic Circumpolar Current which plays an influential role in global ocean circulation as well as gas exchange with the atmosphere. We review the state‐of‐the art knowledge concerning the WG from an interdisciplinary perspective, uncovering critical aspects needed to understand this system's role in shaping the future evolution of oceanic heat and carbon uptake over the next decades. The main limitations in our knowledge are related to the conditions in this extreme and remote environment, where the polar night, very low air temperatures and presence of sea ice year‐round hamper field and remotely sensed measurements. We highlight the importance of winter and under‐ice conditions in the southern WG, the role that new technology will play to overcome present‐day sampling limitations, the importance of the WG connectivity to the low‐latitude oceans and atmosphere, and the expected intensification of the WG circulation as the westerly winds intensify. Greater international cooperation is needed to define key sampling locations that can be visited by any research vessel in the region. Existing transects sampled since the 1980s along the Prime Meridian and along an East‐West section at ~62°S should be maintained with regularity to provide answers to the relevant questions. This approach will provide long‐term data to determine trends and will improve representation of processes for regional, Antarctic‐wide and global modeling efforts – thereby enhancing predictions of the WG in global ocean circulation and climate.
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    Subglacial Geology and Geomorphology of the Pensacola‐Pole Basin, East Antarctica (2019)
    Wiley
    In:  EPIC3Geochemistry Geophysics Geosystems, Wiley, 20, ISSN: 1525-2027
    Details
    Publication Date: 2020-07-02
    Description: The East Antarctic Ice Sheet (EAIS) is underlain by a series of low‐lying subglacial sedimentary basins. The extent, geology, and basal topography of these sedimentary basins are important boundary conditions governing the dynamics of the overlying ice sheet. This is particularly pertinent for basins close to the grounding line wherein the EAIS is grounded below sea level and therefore potentially vulnerable to rapid retreat. Here we analyze newly acquired airborne geophysical data over the Pensacola‐Pole Basin (PPB), a previously unexplored sector of the EAIS. Using a combination of gravity and magnetic and ice‐penetrating radar data, we present the first detailed subglacial sedimentary basin model for the PPB. Radar data reveal that the PPB is defined by a topographic depression situated ~500 m below sea level. Gravity and magnetic depth‐to‐source modeling indicate that the southern part of the basin is underlain by a sedimentary succession 2–3 km thick. This is interpreted as an equivalent of the Beacon Supergroup and associated Ferrar dolerites that are exposed along the margin of East Antarctica. However, we find that similar rocks appear to be largely absent from the northern part of the basin, close to the present‐day grounding line. In addition, the eastern margin of the basin is characterized by a major geological boundary and a system of overdeepened subglacial troughs. We suggest that these characteristics of the basin may reflect the behavior of past ice sheets and/or exert an influence on the present‐day dynamics of the overlying EAIS.
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    The influences of the Arctic troposphere on the midlatitude climate variability and the recent Eurasian cooling (2018)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Atmospheres, Wiley, 123(18), pp. 10162-10184, ISSN: 0148-0227
    Details
    Publication Date: 2019-04-11
    Description: Understanding the influence of the Arctic troposphere on the climate at midlatitudes is critical for projecting the impacts of ongoing and anticipated Arctic changes such as Arctic amplification and rapid sea ice decline over the Northern Hemisphere. In this study, we analyze a suite of atmospheric model experiments, with and without atmospheric relaxation toward reanalysis data, to study the impacts of the Arctic troposphere on the midlatitude atmospheric circulation and climate variability. The Arctic troposphere is found to strongly impact the interannual variability of the atmospheric circulation and temperature over the midlatitude continents. The major mechanisms for the impacts of Arctic troposphere include the modulation of the large‐scale atmospheric circulation, the associated heat transport over the continents, and the impacts on synoptic variations in the North Atlantic‐European sector. The impact of the Arctic troposphere on the intensity of the Siberian High is an important factor for how the Arctic can influence temperature variability in south Siberia and East Asia. The trends in the Arctic troposphere in recent decades are closely linked to the recent winter cooling in Northern Eurasia. These recent cooling trends are not driven by the trends in sea surface temperature/sea ice, tropical atmosphere, and the stratosphere. It is argued that the temperature trend pattern of warm Arctic‐cold Eurasia is a manifestation of two possibly independent phenomena and the cooling trend is contributed to by the Arctic troposphere through impacting the large‐scale atmospheric circulation, the atmospheric blocking frequency, and the intensity of the Siberian High.
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    A global monthly climatology of total alkalinity: a neural network approach (2019)
    Copernicus
    In:  EPIC3Earth System Science Data, Copernicus, 11(3), pp. 1109-1127, ISSN: 1866-3516
    Details
    Publication Date: 2019-08-12
    Repository Name: EPIC Alfred Wegener Institut
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    Climate Noise Influences Ice Sheet Mean State (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, ISSN: 0094-8276
    Details
    Publication Date: 2019-09-16
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    Pacing of Red Sea Deep Water Renewal During the Last Centuries (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 46(8), pp. 4413-4420, ISSN: 0094-8276
    Details
    Publication Date: 2019-10-07
    Description: The Red Sea is a deep marine basin often considered as small‐scale version of the global ocean. Hydrographic observations and ocean‐atmosphere modeling indicate Red Sea deep water was episodically renewed by wintertime open‐ocean deep convections during 1982–2001, suggesting a renewal time on the order of a decade. However, the long‐term pacing of Red Sea deep water renewals is largely uncertain. We use an annually resolved coral oxygen isotope record of winter surface water conditions to show that the late twentieth century deep water renewals were probably unusual in the context of the preceding ~100 years. More frequent major events are detected during the late Little Ice Age, particularly during the early nineteenth century characterized by large tropical volcanic eruptions. We conclude that Red Sea deep water renewal time is on the order of a decade up to a century, depending on the mean climatic conditions and large‐scale interannual climate forcing.
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    Geochemical signatures of pingo ice and its origin in Grøndalen, west Spitsbergen (2019)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 13, pp. 3155-3169
    Details
    Publication Date: 2020-03-01
    Repository Name: EPIC Alfred Wegener Institut
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    Kongsfjorden as harbinger of the future Arctic: knowns, unknowns and research priorities (2019)
    Springer
    In:  EPIC3The Ecosystem of Kongsfjorden, Svalbard, The Ecosystem of Kongsfjorden, Svalbard, Cham, Springer, 566 p., pp. 537-562, ISBN: 978-3-319-46425-1
    Details
    Publication Date: 2020-07-08
    Description: Due to its year-round accessibility and excellent on-site infrastructure, Kongsfjorden and the Ny-Ålesund Research and Monitoring Facility have become established as a primary location to study the impact of environmental change on Arctic coastal ecosystems. Due to its location right at the interface of Arctic and Atlantic oceanic regimes, Kongsfjorden already experiences large amplitudes of variability in physico/chemical conditions and might, thus, be considered as an early warning indicator of future changes, which can then be extrapolated in a pan-Arctic perspective. Already now, Kongsfjorden represents one of the best-studied Arctic fjord systems. However, research conducted to date has concentrated largely on small disciplinary projects, prompting the need for a higher level of integration of future research activities. This contribution, thus, aims at identifying gaps in knowledge and research priorities with respect to ecological and adaptive responses to Arctic ecosystem changes. By doing so we aim to provide a stimulus for the initiation of new international and interdisciplinary research initiatives.
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    Benthic carbon mineralization in hadal trenches: Insights from in-situ determination of benthic oxygen consumption (2018)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 45, pp. 2752-2760, ISSN: 0094-8276
    Details
    Publication Date: 2020-07-02
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    Spatio-temporal variability and decadal trends of snowmelt processes on Antarctic sea ice observed by satellite scatterometers (2019)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 13, pp. 1943-1958
    Details
    Publication Date: 2020-07-10
    Description: The timing and intensity of snowmelt processes on sea ice are key drivers determining the seasonal sea-ice energy and mass budgets. In the Arctic, satellite passive microwave and radar observations have revealed a trend towards an earlier snowmelt onset during the last decades, which is an important aspect of Arctic amplification and sea ice decline. Around Antarctica, snowmelt on perennial ice is weak and very different than in the Arctic, with most snow surviving the summer. Here we compile time series of snowmelt-onset dates on seasonal and perennial Antarctic sea ice from 1992 to 2014/15 using active microwave observations from European Remote Sensing Satellite (ERS-1/2), Quick Scatterometer (QSCAT) and Advanced Scatterometer (ASCAT) radar scatterometers. We define two snowmelt transition stages: A weak backscatter rise indicating the initial warming and destructive metamorphism of the snowpack (pre-melt), followed by a rapid backscatter rise indicating the onset of thaw-freeze cycles (snowmelt). Results show large interannual variability with an average pre-melt onset date of 29 November and melt onset of 10 December, respectively, on perennial ice, without any significant trends over the study period, consistent with the small trends of Antarctic sea ice extent. There was a latitudinal gradient from early snowmelt onsets in mid-November in the northern Weddell Sea to late (end-December) or even absent snowmelt conditions in the southern Weddell Sea. We show that QSCAT Ku-band (13.4 GHz signal frequency) derived pre-melt and snowmelt onset dates are earlier by 20 and 18 days, respectively, than ERS and ASCAT C-band (5.6 GHz) derived dates. This offset has been considered when constructing the time series. Snowmelt onset dates from passive microwave observations (37 GHz) are later by 14 and 6 days than those from the scatterometers, respectively. Based on these characteristic differences between melt onset dates observed by different microwave wavelengths, we developed a conceptual model which illustrates how the seasonal evolution of snow temperature profiles may affect different microwave bands with different penetration depths. These suggest that future multi-frequency active/passive microwave satellite missions could be used to resolve melt processes throughout the vertical snow column of thick snow on perennial Antarctic sea ice.
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    YOUMARES 8 – Oceans Across Boundaries: Learning from each other (2018)
    Springer
    In:  EPIC3Cham, Springer, 259 p., ISBN: 978-3-319-93284-2
    Details
    Publication Date: 2020-06-12
    Description: This open access book presents the proceedings volume of the YOUMARES 8 conference, which took place in Kiel, Germany, in September 2017, supported by the German Association for Marine Sciences (DGM). The YOUMARES conference series is entirely bottom-up organized by and for YOUng MARine RESearchers. Qualified early career scientists moderated the scientific sessions during the conference and provided literature reviews on aspects of their research field. These reviews and the presenters’ conference abstracts are compiled here. Thus, this book discusses highly topical fields of marine research and aims to act as a source of knowledge and inspiration for further reading and research.
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    A synthesis dataset of permafrost-affected soil thermal conditions for Alaska, USA (2018)
    Copernicus
    In:  EPIC3Earth System Science Data, Copernicus, 10(4), pp. 2311-2328, ISSN: 1866-3516
    Details
    Publication Date: 2020-09-06
    Description: Recent observations of near-surface soil temperatures over the circumpolar Arctic show accelerated warming of permafrost-affected soils. The availability of a comprehensive near-surface permafrost and active layer dataset is critical to better understanding climate impacts and to constraining permafrost thermal conditions and its spatial distribution in land system models. We compiled a soil temperature dataset from 72 monitoring stations in Alaska using data collected by the US Geological Survey, the National Park Service, and the University of Alaska Fairbanks permafrost monitoring networks. The array of monitoring stations spans a large range of latitudes from 60.9 to 71.3 N and elevations from near sea level to~ 1300 m, comprising tundra and boreal forest regions. This dataset consists of monthly ground temperatures at depths up to 1 m, volumetric soil water content, snow depth, and air temperature during 1997–2016. These data have been quality controlled in collection and processing. Meanwhile, we implemented data harmonization evaluation for the processed dataset. The final product (PF-AK, v0. 1) is available at the Arctic Data Center (https://doi. org/10.18739/A2KG55).
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    Ocean Heat Transport Into the Barents Sea: Distinct Controls on the Upward Trend and Interannual Variability (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 46(22), pp. 13180-13190, ISSN: 0094-8276
    Details
    Publication Date: 2020-01-07
    Description: Ocean heat transport through the Barents Sea Opening (BSO) has strong impacts on the Barents Sea ice extent and the climate. In this paper we quantified the contributions from different atmospheric forcing components to the trend and interannual variability of the BSO heat transport. Ocean‐ice model simulations were conducted in which the interannual variation of atmospheric forcing was maintained only in or outside the Arctic in two different simulations. The sum of their BSO heat transport anomalies reasonably replicated the trend and variability from a hindcast simulation. The upward trend of the BSO heat transport mainly stems from the increasing ocean temperature in the subpolar North Atlantic. For the interannual variability, the local wind and upstream forcing are similarly important. The location of the Atlantic Water boundary current in the Nordic Seas, influenced by the cyclonic atmospheric circulation, is crucial in determining part of the BSO inflow variability.
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    Lossof a chloroplast encoded function could influence species range in kelp (2019)
    Wiley
    In:  EPIC3Ecology and Evolution, Wiley, 9(15), pp. 1-12
    Details
    Publication Date: 2019-12-28
    Description: Kelps are important providers and constituents of marine ecological niches, the coastal kelp forests. Kelp species have differing distribution ranges, but mainly thrive in temperate and arctic regions. Although the principal factors determining biogeographic distribution ranges are known, genomics could provide additional answers to this question. We sequenced DNA from two Laminaria species with contrasting distribution ranges, Laminaria digitata and Laminaria solidungula. Laminaria digitata is found in the Northern Atlantic with a southern boundary in Brittany (France) or Massachusetts (USA) and a northern boundary in the Arctic, whereas L. solidungula is endemic to the Arctic only. From the raw reads of DNA, we reconstructed both chloroplast genomes and annotated them. A concatenated data set of all available brown algae chloroplast sequences was used for the calculation of a robust phylogeny, and sequence variations were analyzed. The two Laminaria chloroplast genomes are collinear to previously analyzed kelp chloroplast genomes with important exceptions. Rearrangements at the inverted repeat regions led to the pseudogenization of ycf37 in L. solidungula, a gene possibly required under high light conditions. This defunct gene might be one of the reasons why the habitat range of L. solidungula is restricted to lowlight sublittoral sites in the Arctic. The inheritance pattern of single nucleotide polymorphisms suggests incomplete lineage sorting of chloroplast genomes in kelp species. Our analysis of kelp chloroplast genomes shows that not only evolutionary information could be gleaned from sequence data. Concomitantly, those sequences can also tell us something about the ecological conditions which are required for species well‐being.
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    Die Wälder der Antarktis (2019)
    Wiley
    In:  EPIC3Biologie in unserer Zeit, Wiley, 49(6), pp. 436-442, ISSN: 0045-205X
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    Publication Date: 2019-12-20
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    Evaluation of FESOM2.0 Coupled to ECHAM6.3: Preindustrial and HighResMIP Simulations (2019)
    Wiley
    In:  EPIC3Journal of Advances in Modeling Earth Systems, Wiley, 11(11), pp. 3794-3815, ISSN: 1942-2466
    Details
    Publication Date: 2021-02-16
    Description: A new global climate model setup using FESOM2.0 for the sea ice‐ocean component and ECHAM6.3 for the atmosphere and land surface has been developed. Replacing FESOM1.4 by FESOM2.0 promises a higher efficiency of the new climate setup compared to its predecessor. The new setup allows for long‐term climate integrations using a locally eddy‐resolving ocean. Here it is evaluated in terms of (1) the mean state and long‐term drift under preindustrial climate conditions, (2) the fidelity in simulating the historical warming, and (3) differences between coarse and eddy‐resolving ocean configurations. The results show that the realism of the new climate setup is overall within the range of existing models. In terms of oceanic temperatures, the historical warming signal is of smaller amplitude than the model drift in case of a relatively short spin‐up. However, it is argued that the strategy of “de‐drifting” climate runs after the short spin‐up, proposed by the HighResMIP protocol, allows one to isolate the warming signal. Moreover, the eddy‐permitting/resolving ocean setup shows notable improvements regarding the simulation of oceanic surface temperatures, in particular in the Southern Ocean.
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    Evaluating model outputs using integrated global speleothem records of climate change since the last glacial (2019)
    Copernicus
    In:  EPIC3Climate of the Past, Copernicus, 15(4), pp. 1557-1579, ISSN: 1814-9332
    Details
    Publication Date: 2020-01-27
    Description: Although quantitative isotope data from speleothems has been used to evaluate isotope-enabled model simulations, currently no consensus exists regarding the most appropriate methodology through which to achieve this. A number of modelling groups will be running isotope-enabled palaeoclimate simulations in the framework of the Coupled Model Intercomparison Project Phase 6, so it is timely to evaluate different approaches to using the speleothem data for data–model comparisons. Here, we illustrate this using 456 globally distributed speleothem δ18O records from an updated version of the Speleothem Isotopes Synthesis and Analysis (SISAL) database and palaeoclimate simulations generated using the ECHAM5-wiso isotope-enabled atmospheric circulation model. We show that the SISAL records reproduce the first-order spatial patterns of isotopic variability in the modern day, strongly supporting the application of this dataset for evaluating model-derived isotope variability into the past. However, the discontinuous nature of many speleothem records complicates the process of procuring large numbers of records if data–model comparisons are made using the traditional approach of comparing anomalies between a control period and a given palaeoclimate experiment. To circumvent this issue, we illustrate techniques through which the absolute isotope values during any time period could be used for model evaluation. Specifically, we show that speleothem isotope records allow an assessment of a model’s ability to simulate spatial isotopic trends. Our analyses provide a protocol for using speleothem isotope data for model evaluation, including screening the observations to take into account the impact of speleothem mineralogy on δ18O values, the optimum period for the modern observational baseline and the selection of an appropriate time window for creating means of the isotope data for palaeo-time-slices.
    Repository Name: EPIC Alfred Wegener Institut
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  • 96
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    Water isotopes - climate relationships for the mid-Holocene and preindustrial period simulated with an isotope-enabled version of MPI-ESM (2019)
    Copernicus
    In:  EPIC3Climate of the Past, Copernicus, 15(6), pp. 1913-1937, ISSN: 1814-9332
    Details
    Publication Date: 2020-01-27
    Description: We present here the first results, for the preindustrial and mid-Holocene climatological periods, of the newly developed isotope-enhanced version of the fully coupled Earth system model MPI-ESM, called hereafter MPI-ESM-wiso. The water stable isotopes H16O, H18O and HDO have been implemented into all components of the coupled model setup. The mid-Holocene provides the opportunity to evaluate the model response to changes in the seasonal and latitudinal distribution of insolation induced by different orbital forcing conditions. The results of our equilibrium simulations allow us to evaluate the performance of the isotopic model in simulating the spatial and temporal variations of water isotopes in the different compartments of the hydrological system for warm climates. For the preindustrial climate, MPI-ESM-wiso reproduces very well the observed spatial distribution of the isotopic content in precipitation linked to the spatial variations in temperature and precipitation rate. We also find a good model–data agreement with the observed distribution of isotopic composition in surface seawater but a bias with the presence of surface seawater that is too 18O-depleted in the Arctic Ocean. All these results are improved compared to the previous model version ECHAM5/MPIOM. The spatial relationships of water isotopic composition with temperature, precipitation rate and salinity are consistent with observational data. For the preindustrial climate, the interannual relationships of water isotopes with temperature and salinity are globally lower than the spatial ones, consistent with previous studies. Simulated results under mid-Holocene conditions are in fair agreement with the isotopic measurements from ice cores and continental speleothems. MPI-ESM-wiso simulates a decrease in the isotopic composition of precipitation from North Africa to the Tibetan Plateau via India due to the enhanced monsoons during the mid-Holocene. Over Greenland, our simulation indicates a higher isotopic composition of precipitation linked to higher summer temperature and a reduction in sea ice, shown by positive isotope–temperature gradient. For the Antarctic continent, the model simulates lower isotopic values over the East Antarctic plateau, linked to the lower temperatures during the mid-Holocene period, while similar or higher isotopic values are modeled over the rest of the continent. While variations of isotopic contents in precipitation over West Antarctica between mid-Holocene and preindustrial periods are partly controlled by changes in temperature, the transport of relatively 18O-rich water vapor near the coast to the western ice core sites could play a role in the final isotopic composition. So, more caution has to be taken about the reconstruction of past temperature variations during warm periods over this area. The coupling of such a model with an ice sheet model or the use of a zoomed grid centered on this region could help to better describe the role of the water vapor transport and sea ice around West Antarctica. The reconstruction of past salinity through isotopic content in sea surface waters can be complicated for regions with strong ocean dynamics, variations in sea ice regimes or significant changes in freshwater budget, giving an extremely variable relationship between the isotopic content and salinity of ocean surface waters over small spatial scales. These complicating factors demonstrate the complexity of interpreting water isotopes as past climate signals of warm periods like the mid-Holocene. A systematic isotope model intercomparison study for further insights on the model dependency of these results would be beneficial.
    Repository Name: EPIC Alfred Wegener Institut
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  • 97
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    Hydroclimate in the Pamirs Was Driven by Changes in Precipitation‐Evaporation Seasonality Since theLast Glacial Period (2019)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 46(23), pp. 13972-13983, ISSN: 0094-8276
    Details
    Publication Date: 2020-01-27
    Description: The Central Asian Pamir Mountains (Pamirs) are a high‐altitude region sensitive to climatic change, with only few paleoclimatic records available. To examine the glacial‐interglacial hydrological changes in the region, we analyzed the geochemical parameters of a 31‐kyr record from Lake Karakul and performed a set of experiments with climate models to interpret the results. δD values of terrestrial biomarkers showed insolation‐driven trends reflecting major shifts of water vapor sources. For aquatic biomarkers, positive δD shifts driven by changes in precipitation seasonality were observed at ca. 31–30, 28–26, and 17–14 kyr BP. Multiproxy paleoecological data and modelling results suggest that increased water availability, induced by decreased summer evaporation, triggered higher lake levels during those episodes, possibly synchronous to northern hemispheric rapid climate events. We conclude that seasonal changes in precipitation‐evaporation balance significantly influenced the hydrological state of a large waterbody such as Lake Karakul, while annual precipitation amount and inflows remained fairly constant.
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  • 98
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    Scaling-up permafrost thermal measurements in western Alaska using an ecotype approach (2016)
    Copernicus
    In:  EPIC3The Cryosphere, Copernicus, 10(5), pp. 2517-2532, ISSN: 1994-0424
    Details
    Publication Date: 2020-09-06
    Description: Permafrost temperatures are increasing in Alaska due to climate change and in some cases permafrost is thawing and degrading. In areas where degradation has already occurred the effects can be dramatic, resulting in changing ecosystems, carbon release, and damage to infrastructure. However, in many areas we lack baseline data, such as subsurface temperatures, needed to assess future changes and potential risk areas. Besides climate, the physical properties of the vegetation cover and subsurface material have a major influence on the thermal state of permafrost. These properties are often directly related to the type of ecosystem overlaying permafrost. In this paper we demonstrate that classifying the landscape into general ecotypes is an effective way to scale up permafrost thermal data collected from field monitoring sites. Additionally, we find that within some ecotypes the absence of a moss layer is indicative of the absence of near-surface permafrost. As a proof of concept, we used the ground temperature data collected from the field sites to recode an ecotype land cover map into a map of mean annual ground temperature ranges at 1 m depth based on analysis and clustering of observed thermal regimes. The map should be useful for decision making with respect to land use and understanding how the landscape might change under future climate scenarios.
    Repository Name: EPIC Alfred Wegener Institut
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  • 99
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    Spatiotemporal variation of the bacterioplankton community in the German Bight: from estuarine to offshore regions (2016)
    Springer
    In:  EPIC3Helgoland Marine Research, Springer
    Details
    Publication Date: 2016-10-24
    Description: Marine microbial biogeography has been studied intensively; however few studies address community variation across temporal and spatial scales simultaneously so far. Here we present a yearlong study investigating the dynamics of the free-living and particle-attached bacterioplankton community across a 100 km transect in the German Bight reaching from the Elbe estuary towards the open North Sea. Community composition was assessed using automated ribosomal intergenic spacer analysis and linked to environmental parameters applying multivariate statistical techniques. Results suggest that the spatial variation of the bacterioplankton community is defined by hydrographic current conditions, which separate the inner German Bight from the open North Sea and lead to pronounced differences in the coastal and offshore bacterioplankton community. However this spatial variation is overwhelmed by a strong temporal variation which is triggered by temperature as the main driving force throughout the whole transect. Variation in the free-living community was predominantly driven by temperature, whereas the particle-attached community exhibited stronger spatial variation patterns.
    Repository Name: EPIC Alfred Wegener Institut
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    Subglacial roughness of the former Barents Sea ice sheet (2013)
    Wiley
    In:  EPIC3Journal of Geophysical Research-Earth Surface, Wiley, 118(4), pp. 2546-2556, ISSN: 0148-0227
    Details
    Publication Date: 2016-11-15
    Description: The roughness of a glacier bed has high importance for the estimation of the sliding velocity and can also provide valuable insights into the dynamics and history of ice sheets, depending on scale. Measurement of basal properties in present-day ice sheets is restricted to ground-penetrating radar and seismics, with surveys retrieving relatively coarse data sets. Deglaciated areas, like the Barents Sea, can be surveyed by shipborne 2-D and 3-D seismics and multibeam sonar and provide the possibility of studying the basal roughness of former ice sheets and ice streams with high resolution. Here, for the first time, we quantify the subglacial roughness of the former Barents Sea ice sheet by estimating the spectral roughness of the basal topography. We also make deductions about the past flow directions by investigating how the roughness varies along a 2-D line as the orientation of the line changes. Lastly, we investigate how the estimated basal roughness is affected by the resolution of the basal topography data set by comparing the spectral roughness along a cross section using various sampling intervals. We find that the roughness typically varies on a similar scale as for other previously marine-inundated areas in West Antarctica, with subglacial troughs having very low roughness, consistent with fast ice flow and high rates of basal erosion. The resolution of the data set seems to be of minor importance when comparing roughness indices calculated with a fixed profile length. A strong dependence on track orientation is shown for all wavelengths, with profiles having higher roughness across former flow directions than along them.
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