Wilhelms, Frank

[["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Geophysical Research Letters"],["dc.bibliographiccitation.volume","47"],["dc.contributor.affiliation","Hattermann, Tore; 2\r\nNorwegian Polar Institute\r\nTromsø Norway"],["dc.contributor.affiliation","Kuhn, Gerhard; 1\r\nAlfred‐Wegener‐Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung\r\nBremerhaven Germany"],["dc.contributor.affiliation","Gaedicke, Christoph; 3\r\nBGR, Federal Institute for Geosciences and Natural Resources\r\nHannover Germany"],["dc.contributor.affiliation","Berger, Sophie; 1\r\nAlfred‐Wegener‐Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung\r\nBremerhaven Germany"],["dc.contributor.affiliation","Drews, Reinhard; 4\r\nDepartment of Geosciences\r\nUniversity of Tübingen\r\nTübingen Germany"],["dc.contributor.affiliation","Ehlers, Todd A.; 4\r\nDepartment of Geosciences\r\nUniversity of Tübingen\r\nTübingen Germany"],["dc.contributor.affiliation","Franke, Dieter; 3\r\nBGR, Federal Institute for Geosciences and Natural Resources\r\nHannover Germany"],["dc.contributor.affiliation","Gromig, Rapahel; 1\r\nAlfred‐Wegener‐Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung\r\nBremerhaven Germany"],["dc.contributor.affiliation","Hofstede, Coen; 1\r\nAlfred‐Wegener‐Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung\r\nBremerhaven Germany"],["dc.contributor.affiliation","Lambrecht, Astrid; 6\r\nGeodesy and Glaciology\r\nBavarian Academy of Sciences and Humanities\r\nMunich Germany"],["dc.contributor.affiliation","Läufer, Andreas; 3\r\nBGR, Federal Institute for Geosciences and Natural Resources\r\nHannover Germany"],["dc.contributor.affiliation","Mayer, Christoph; 6\r\nGeodesy and Glaciology\r\nBavarian Academy of Sciences and Humanities\r\nMunich Germany"],["dc.contributor.affiliation","Tiedemann, Ralf; 1\r\nAlfred‐Wegener‐Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung\r\nBremerhaven Germany"],["dc.contributor.affiliation","Wilhelms, Frank; 1\r\nAlfred‐Wegener‐Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung\r\nBremerhaven Germany"],["dc.contributor.affiliation","Eisen, Olaf; 1\r\nAlfred‐Wegener‐Institut Helmholtz‐Zentrum für Polar‐ und Meeresforschung\r\nBremerhaven Germany"],["dc.contributor.author","Smith, Emma C."],["dc.contributor.author","Hattermann, Tore"],["dc.contributor.author","Kuhn, Gerhard"],["dc.contributor.author","Gaedicke, Christoph"],["dc.contributor.author","Berger, Sophie"],["dc.contributor.author","Drews, Reinhard"],["dc.contributor.author","Ehlers, Todd A."],["dc.contributor.author","Franke, Dieter"],["dc.contributor.author","Gromig, Rapahel"],["dc.contributor.author","Hofstede, Coen"],["dc.contributor.author","Lambrecht, Astrid"],["dc.contributor.author","Läufer, Andreas"],["dc.contributor.author","Mayer, Christoph"],["dc.contributor.author","Tiedemann, Ralf"],["dc.contributor.author","Wilhelms, Frank"],["dc.contributor.author","Eisen, Olaf"],["dc.date.accessioned","2021-04-14T08:25:51Z"],["dc.date.available","2021-04-14T08:25:51Z"],["dc.date.issued","2020"],["dc.date.updated","2022-02-09T13:21:56Z"],["dc.description.abstract","Abstract The shape of ice shelf cavities are a major source of uncertainty in understanding ice‐ocean interactions. This limits assessments of the response of the Antarctic ice sheets to climate change. Here we use vibroseis seismic reflection surveys to map the bathymetry beneath the Ekström Ice Shelf, Dronning Maud Land. The new bathymetry reveals an inland‐sloping trough, reaching depths of 1,100 m below sea level, near the current grounding line, which we attribute to erosion by palaeo‐ice streams. The trough does not cross‐cut the outer parts of the continental shelf. Conductivity‐temperature‐depth profiles within the ice shelf cavity reveal the presence of cold water at shallower depths and tidal mixing at the ice shelf margins. It is unknown if warm water can access the trough. The new bathymetry is thought to be representative of many ice shelves in Dronning Maud Land, which together regulate the ice loss from a substantial area of East Antarctica."],["dc.description.abstract","Plain Language Summary Antarctica is surrounded by floating ice shelves, which play a crucial role in regulating the flow of ice from the continent into the oceans. The ice shelves are susceptible to melting from warm ocean waters beneath them. In order to better understand the melting, knowledge of the shape and depth of the ocean cavity beneath ice shelves is crucial. In this study, we present new measurements of the sea floor depth beneath Ekström Ice Shelf in East Antarctica. The measurements reveal a much deeper sea floor than previously known. We discuss the implications of this for access of warm ocean waters, which can melt the base of the ice shelf and discuss how the observed sea floor features were formed by historical ice flow regimes. Although Ekström Ice Shelf is relatively small, the geometry described here is thought to be representative of the topography beneath many ice shelves in this region, which together regulate the ice loss from a substantial area of East Antarctica."],["dc.description.abstract","Key Points Vibroseis seismic surveys used to map the ice shelf cavity beneath Ekström Ice Shelf in Antarctica Deep trough with transverse sills and overdeepenings provide evidence of past ice streaming and retreat Two ocean circulation regimes inferred in the shallow and deep parts of the cavity"],["dc.description.sponsorship","Belgian Science Policy Contract"],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659"],["dc.description.sponsorship","DFG Cost S2S project"],["dc.description.sponsorship","RD http://dx.doi.org/10.13039/100009936"],["dc.identifier.doi","10.1029/2019GL086187"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/81748"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-399"],["dc.relation.eissn","1944-8007"],["dc.relation.issn","0094-8276"],["dc.rights","This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited."],["dc.title","Detailed Seismic Bathymetry Beneath Ekström Ice Shelf, Antarctica: Implications for Glacial History and Ice‐Ocean Interaction"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.journal","Frontiers in Earth Science"],["dc.bibliographiccitation.volume","4"],["dc.contributor.author","Karlsson, Nanna B."],["dc.contributor.author","Eisen, Olaf"],["dc.contributor.author","Dahl-Jensen, Dorthe"],["dc.contributor.author","Freitag, Johannes"],["dc.contributor.author","Kipfstuhl, Sepp"],["dc.contributor.author","Lewis, Cameron"],["dc.contributor.author","Nielsen, Lisbeth T."],["dc.contributor.author","Paden, John D."],["dc.contributor.author","Winter, Anna"],["dc.contributor.author","Wilhelms, Frank"],["dc.date.accessioned","2020-12-10T18:44:21Z"],["dc.date.available","2020-12-10T18:44:21Z"],["dc.date.issued","2016"],["dc.description.abstract","Radar-detected internal layering contains information on past accumulation rates and patterns. In this study, we assume that the radar layers are isochrones, and use the layer stratigraphy in combination with ice-core measurements and numerical methods to retrieve accumulation information for the northern part of central Greenland. Measurements of the dielectric properties of an ice core from the NEEM (North Greenland Eemian Ice Drilling) site, allow for correlation of the radar layers with volcanic horizons to obtain an accurate age of the layers. We obtain 100 a averaged accumulation patterns for the period 1311–2011 for a 300 by 350 km area encompassing the two ice-core sites: NEEM and NGRIP (North Greenland Ice Core Project). Our results show a clear trend of high accumulation rates west of the ice divide and low accumulation rates east of the ice divide. At the NEEM site, this accumulation pattern persists throughout our study period with only minor temporal variations in the accumulation rate. In contrast, the accumulation rate shows more pronounced temporal variations (based on our centennial averages) from 170 km south of the NEEM site to the NGRIP site. We attribute this variation to shifts in the location of the high–low accumulation boundary away from the ice divide."],["dc.identifier.doi","10.3389/feart.2016.00097"],["dc.identifier.eissn","2296-6463"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/78421"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.publisher","Frontiers Media S.A."],["dc.relation.eissn","2296-6463"],["dc.rights","http://creativecommons.org/licenses/by/4.0/"],["dc.title","Accumulation Rates during 1311–2011 CE in North-Central Greenland Derived from Air-Borne Radar Data"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.journal","Journal of Glaciology"],["dc.bibliographiccitation.lastpage","13"],["dc.contributor.author","Mojtabavi, Seyedhamidreza"],["dc.contributor.author","Eisen, Olaf"],["dc.contributor.author","Franke, Steven"],["dc.contributor.author","Jansen, Daniela"],["dc.contributor.author","Steinhage, Daniel"],["dc.contributor.author","Paden, John"],["dc.contributor.author","Dahl-Jensen, Dorthe"],["dc.contributor.author","Weikusat, Ilka"],["dc.contributor.author","Eichler, Jan"],["dc.contributor.author","Wilhelms, Frank"],["dc.date.accessioned","2022-04-01T10:00:52Z"],["dc.date.available","2022-04-01T10:00:52Z"],["dc.date.issued","2022"],["dc.description.abstract","Abstract During the past 20 years, multi-channel radar emerged as a key tool for deciphering an ice sheet's internal architecture. To assign ages to radar reflections and connect them over large areas in the ice sheet, the layer genesis has to be understood on a microphysical scale. Synthetic radar trace modelling based on the dielectric profile of ice cores allows for the assignation of observed physical properties’ variations on the decimetre scale to radar reflectors extending from the coring site to a regional or even whole-ice-sheet scale. In this paper we rely on the available dielectric profiling data of the northern Greenland deep ice cores: NGRIP, NEEM and EGRIP. The three records are well suited for assigning an age model to the stratigraphic radar-mapped layers, and linking up the reflector properties to observations in the cores. Our modelling results show that the internal reflections are mainly due to conductivity changes. Furthermore, we deduce fabric characteristics at the EGRIP drill site from two-way-travel-time differences of along and across-flow polarized radarwave reflections of selected horizons (below 980 m). These indicate in deeper parts of the ice column an across-flow concentrated c -axis fabric."],["dc.identifier.doi","10.1017/jog.2021.137"],["dc.identifier.pii","S0022143021001374"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/105536"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-530"],["dc.relation.eissn","1727-5652"],["dc.relation.issn","0022-1430"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0/"],["dc.title","Origin of englacial stratigraphy at three deep ice core sites of the Greenland Ice Sheet by synthetic radar modelling"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","194"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Journal of Marine Science and Engineering"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Gong, Da"],["dc.contributor.author","Fan, Xiaopeng"],["dc.contributor.author","Li, Yazhou"],["dc.contributor.author","Li, Bing"],["dc.contributor.author","Zhang, Nan"],["dc.contributor.author","Gromig, Raphael"],["dc.contributor.author","Smith, Emma C."],["dc.contributor.author","Dummann, Wolf"],["dc.contributor.author","Berger, Sophie"],["dc.contributor.author","Eisen, Olaf"],["dc.contributor.author","Tell, Jan"],["dc.contributor.author","Biskaborn, Boris K."],["dc.contributor.author","Koglin, Nikola"],["dc.contributor.author","Broy, Benjamin"],["dc.contributor.author","Liu, Yunchen"],["dc.contributor.author","Yang, Yang"],["dc.contributor.author","Li, Xingchen"],["dc.contributor.author","Talalay, Pavel"],["dc.contributor.author","Wilhelms, Frank"],["dc.contributor.author","Liu, An"],["dc.date.accessioned","2020-12-10T18:47:14Z"],["dc.date.available","2020-12-10T18:47:14Z"],["dc.date.issued","2019"],["dc.description.sponsorship","National Natural Science Foundation of China"],["dc.description.sponsorship","Program for Jilin University Science and Technology Innovative Research Team"],["dc.identifier.doi","10.3390/jmse7060194"],["dc.identifier.eissn","2077-1312"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/78688"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.publisher","MDPI"],["dc.relation.eissn","2077-1312"],["dc.rights","https://creativecommons.org/licenses/by/4.0/"],["dc.title","Coring of Antarctic Subglacial Sediments"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]