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  • 1
    Publication Date: 2022-06-26
    Description: The Arctic is warming faster than anywhere else on Earth, prompting glacial melt, permafrost thaw, and sea ice decline. These severe consequences induce feedbacks that contribute to amplified warming, affecting weather and climate globally. Aerosols and clouds play a critical role in regulating radiation reaching the Arctic surface. However, the magnitude of their effects is not adequately quantified, especially in the central Arctic where they impact the energy balance over the sea ice. Specifically, aerosols called ice nucleating particles (INPs) remain understudied yet are necessary for cloud ice production and subsequent changes in cloud lifetime, radiative effects, and precipitation. Here, we report observations of INPs in the central Arctic over a full year, spanning the entire sea ice growth and decline cycle. Further, these observations are size-resolved, affording valuable information on INP sources. Our results reveal a strong seasonality of INPs, with lower concentrations in the winter and spring controlled by transport from lower latitudes, to enhanced concentrations of INPs during the summer melt, likely from marine biological production in local open waters. This comprehensive characterization of INPs will ultimately help inform cloud parameterizations in models of all scales.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
    Publication Date: 2022-06-28
    Description: Braided reaches were common along near‐natural Alpine rivers, and the associated habitat dynamics supported plant and animal species specialized on early‐successional stages. The extensive riparian zones could mitigate climate change by absorbing floods and by retaining water during droughts. Human impacts largely reduced active river corridors through altered discharge and construction of dykes, while recent restoration projects aim at increasing river dynamics. The causes and consequences of Alpine river degradation are well understood, but there are only few quantitative studies on floodplain degradation and restoration. Thus, we have reconstructed historical changes of gravel bars along five Alpine rivers (Iller, Inn, Isar, Lech, and Wertach) in Southern Germany in the period 1808–2009, based on historical maps and aerial images. We found losses of 〉90% in gravel bar area along these rivers since the mid‐19th century. The decline was caused by a reduction of the active river corridor and by ongoing succession of the remaining open habitats. Within the past 30 years, at the Isar River, restoration measures were realized with the aim to widen the active river corridor and to recreate gravel bars. In four restored reaches, we found that 5% of the historical gravel bar area recovered, and that the proportion of restored gravel bar area was highest after intermediate flooding. We conclude that the active river corridors of German Alpine rivers are almost completely lost, and that more extensive restoration needs to be done to preserve the habitat dynamics and biodiversity of these systems, and to adapt Alpine rivers to climate change.
    Description: Deutsche Bundesstiftung Umwelt http://dx.doi.org/10.13039/100007636
    Keywords: ddc:551.35
    Language: English
    Type: doc-type:article
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  • 3
    Publication Date: 2022-10-20
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Loranger, S., & Weber, T. C. . Shipboard acoustic observations of flow rate from a seafloor-sourced oil spill. Journal of Geophysical Research: Oceans, 125(10), (2020): e2020JC016274, https://doi.org/10.1029/2020JC016274.
    Description: In 2004 a debris flow generated by Hurricane Ivan toppled an oil production platform in Mississippi Canyon lease block 20 (MC20). Between 2004 and the installation of a containment system in 2019 MC20 became an in situ laboratory for a wide range of hydrocarbon in the sea‐related research, including different methods of assessing the volumetric flow rate of hydrocarbons spanning different temporal scales. In 2017 a shipboard acoustic Doppler current profiler (ADCP) and high‐frequency (90 to 154 kHz) broadband echosounder were deployed to assess the flow rate of liquid and gas phase hydrocarbons. Measurements of horizontal currents were combined with acoustic mapping to determine the rise velocity of the seep as it moved downstream. Models of the rise velocity for fluid particles were used to predict the size of oil droplets and gas bubbles in the seep. The amplitude and shape of the broadband acoustic backscatter were then used to differentiate between, and determine the flow rate of, hydrocarbons. Oil flow rate in the seep was estimated to be 56 to 86 barrels/day (mean urn:x-wiley:jgrc:media:jgrc24228:jgrc24228-math-0001 barrels/day) while the flow rate of gaseous hydrocarbons was estimated to be 98 to 359 m3/day (mean urn:x-wiley:jgrc:media:jgrc24228:jgrc24228-math-0002 m3/day).
    Description: The work was supported by the National Oceanic and Atmospheric Administration (Grant NA15NOS4000200).
    Keywords: Oil spill ; Acoustics ; Flow rate ; MC20
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
    Publication Date: 2022-10-04
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 5
    Publication Date: 2022-08-03
    Description: The NY-Ålesund TurbulencE Fiber Optic eXperiment (NYTEFOX) was a field experiment at the Ny-Ålesund Arctic site (78.9◦ N, 11.9◦ E) and yielded a unique meteorological data set. These data describe the distribution of heat, airflows, and exchange in the Arctic boundary layer for a period of 14 d from 26 February to 10 March 2020. NYTEFOX is the first field experiment to investigate the heterogeneity of airflow and its transport of temperature, wind, and kinetic energy in the Arctic environment using the fiber-optic distributed sensing (FODS) technique for horizontal and vertical observations. FODS air temperature and wind speed were observed at a spatial resolution of 0.127 m and a temporal resolution of 9 s along a 700 m horizontal array at 1 m above ground level (a.g.l.) and along three 7 m vertical profiles. Ancillary data were collected from three sonic anemometers and an acoustic profiler (minisodar; sodar is an acronym for “sound detection and ranging”) yielding turbulent flow statistics and vertical profiles in the lowest 300 m a.g.l., respectively. The observations from this field campaign are publicly available on Zenodo (https://doi.org/10.5281/zenodo.4756836, Huss et al., 2021) and supplement the meteorological data set operationally collected by the Baseline Surface Radiation Network (BSRN) at Ny-Ålesund, Svalbard.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 6
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: This report presents the results of gravity measurements obtained aboard the Research Vessel CHAIN of the Woods Hole Oceanographic Institution during cruise 7 3, 6 to 26 September 1967. Information on bathymetry and other studies conducted during CHAIN cruise 73 may be found in W.H.O.I. Reference No. 68-50 (Knott, et al., 1968). Gravity measurements were made simultaneously with the Massachusetts Institute of Technology (MIT) vibrating string gravity meter and with LaCoste and Romberg sea gravity meter number S-13. The data presented is a selective composite of information from both meters . The base reference station used for the measurements is at the W. H. 0. I. dock in Woods Hole, Massachusetts. Its gravity value was taken to be 980327. 0 mgal, however, recent ties of this station to national gravity network stations (Anonymous, 1965) in the Boston, Massachusetts area indicate that this reading is high by about 1. 4 mgal. Thermal and electrical difficulties with the MIT meter made port-to-port drift prediction uncertain (Bowin, Wing and Aldrich, in press). Drift rate for this meter was determined on the basis of its continuous averaged differences with the LaCoste and Romberg meter. This method showed the MIT meter drifting with respect to the LaCoste and Romberg meter by+ 1. 611 mgal per day for the cruise period. Drift of the LaCoste and Romberg gravity meter during CHAIN 73 was - 0.026 mgal/day from in-port measurements at beginning and end of cruise. This last drift value is anomalous in sign and magnitude with respect to the meter's over-all drift rate , and was not applied. The accuracy of the sea measurements is estimated to be about ±10 mgal (Bowin, Wing, and Aldrich, in press). Free -air anomaly values were calculated using the 1930 International Gravity Formula. Water depths are in meters corrected according to the tables of Matthews ( 1939). Bouguer anomaly values were calculated using an infinite slab correction and an assumed crustal density of 2. 67 gm/cm3 . A density of 1. 03 gm/cm3 was assumed for sea water.
    Description: The National Science Foundation Grant GA-9?6 and submitted to the Office of Naval Research under Contract Nonr-4029(00)~ NR 260-101.
    Keywords: Gravity--Measuremnent--Caribbean Sea ; Gravity--Measurement--North Atlantic Ocean ; Gravity anomalies
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 7
    Publication Date: 2022-05-26
    Description: © The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Zhang, Y., Kieft, B., Hobson, B. W., Ryan, J. P., Barone, B., Preston, C. M., Roman, B., Raanan, B., Marin,Roman,,III, O'Reilly, T. C., Rueda, C. A., Pargett, D., Yamahara, K. M., Poulos, S., Romano, A., Foreman, G., Ramm, H., Wilson, S. T., DeLong, E. F., Karl, D. M., Birch, J. M., Bellingham, J. G., & Scholin, C. A. Autonomous tracking and sampling of the deep chlorophyll maximum layer in an open-ocean eddy by a long-range autonomous underwater vehicle. IEEE Journal of Oceanic Engineering, 45(4), (2020): 1308-1321, doi:10.1109/JOE.2019.2920217.
    Description: Phytoplankton communities residing in the open ocean, the largest habitat on Earth, play a key role in global primary production. Through their influence on nutrient supply to the euphotic zone, open-ocean eddies impact the magnitude of primary production and its spatial and temporal distributions. It is important to gain a deeper understanding of the microbial ecology of marine ecosystems under the influence of eddy physics with the aid of advanced technologies. In March and April 2018, we deployed autonomous underwater and surface vehicles in a cyclonic eddy in the North Pacific Subtropical Gyre to investigate the variability of the microbial community in the deep chlorophyll maximum (DCM) layer. One long-range autonomous underwater vehicle (LRAUV) carrying a third-generation Environmental Sample Processor (3G-ESP) autonomously tracked and sampled the DCM layer for four days without surfacing. The sampling LRAUV's vertical position in the DCM layer was maintained by locking onto the isotherm corresponding to the chlorophyll peak. The vehicle ran on tight circles while drifting with the eddy current. This mode of operation enabled a quasi-Lagrangian time series focused on sampling the temporal variation of the DCM population. A companion LRAUV surveyed a cylindrical volume around the sampling LRAUV to monitor spatial and temporal variation in contextual water column properties. The simultaneous sampling and mapping enabled observation of DCM microbial community in its natural frame of reference.
    Description: 10.13039/501100008982 - National Science Foundation 10.13039/100000936 - Gordon and Betty Moore Foundation 10.13039/100000008 - David and Lucile Packard Foundation 10.13039/100016377 - Schmidt Ocean Institute 10.13039/100000893 - Simons Foundation
    Keywords: Autonomous underwater vehicle (AUV) ; eddy ; Environmental Sample Processor (ESP) ; phytoplankton ; sampling ; tracking
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 8
    Publication Date: 2022-05-24
    Description: Changing redox conditions in water columns or sediment–water interfaces of lakes are captured as sedimentary archives, and are often influenced by climate. Their study therefore permits the reconstruction of past climate change on (sub-) annual to longer timescales. In Lago Fagnano (54°S Argentina/Chile), a large oligotrophic and deep-oxygenated lake, alternations of light grey clay and dark greenish and black laminae are preserved throughout the Holocene sedimentary record. This study aims to clarify the mechanism of laminae formation and preservation in Lago Fagnano, and their relation to changing redox conditions in the lake. High-resolution major element scanning and mapping along with detailed mineralogical analyses of sediment cores allowed identifying Fe-oxides, Mn-oxides and Fe-(mono) sulphides as responsible for the lamination. Based on the interpretation of redox processes at the current sedimentary redox boundary and of buried palaeo-redox fronts underlying mass-transported deposits, the greenish laminae enriched in Fe-oxides are interpreted as palaeo-redox fronts. The preservation of such former interfaces in Lago Fagnano sediments is most likely promoted by rapid increases of sedimentation due to higher runoff related to stronger Southern Hemisphere Westerlies. The formation of black laminae, showing only traces of Fe-(mono) sulphides and organic matter, is obscured by oxidation and early diagenetic processes, i.e. degradation and partial pyritization. These layers were presumably generated by small changes in bottom-water oxygenation due to reduced mixing and/or higher productivity. This study highlights the value of high-resolution sediment−geochemical analyses to better understand redox and diagenetic processes in oligotrophic mixed lakes.
    Type: info:eu-repo/semantics/article
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  • 9
    Publication Date: 2022-07-18
    Description: The German Seismological Broadband Array (Deutsches Seismologisches Breitband Array [DSEBRA]) comprises 100 mobile seismological stations and can be deployed as a stand‐alone network or in conjunction with other stations to build an even larger array. The first mission of DSEBRA was in the framework of the European AlpArray initiative. The aim of the project is to understand the deep structure, mantle dynamics, plate tectonics, its linkage to surface processes, and seismic hazard of the Alps–Apennines–Carpathians–Dinarides orogenic system. DSEBRA, purchased in the framework of the German Priority Program Mountain Building Processes in 4D, contributed to one‐third of the temporary AlpArray seismic network (AASN). The stations are currently deployed in the Alpine foreland of Germany and Austria, in the high Alps of Austria and Italy, and in the Pannonian basins of Hungary. The stations are equipped with state‐of‐the‐art technology, thus allowing to acquire high‐quality broadband data in real time. In this article, we present the current station deployment within the AASN, describing the equipment and its handling. Furthermore, we discuss the data quality and perform noise analyses. In conclusion, DSEBRA stations provide excellent data and are very well suited for deployment in national or international seismological experiments.
    Type: info:eu-repo/semantics/article
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