Description: Multibeam data were collected during RV Polarstern cruise PS98 (2016-04-10 to 2016-05-11). Multibeam sonar system was Atlas Hydrographic Hydrosweep DS 3 multibeam echo sounder. Data are processed with Caris HIPS, including sound velocity correction with SV data from World Ocean Atlas 13 (https://doi.org/10.7289/v5f769gt), tidal correction with TPXO9_atlas_v5 (https://www.tpxo.net/global/tpxo9-atlas), and manual cleaning. The soundings are combined in daily files, the format is XYZ ASCII (〈Lon〉 〈Lat〉 〈Depth in meters, positive up, relative to mean sea level〉). Additional blockmedian grids have been computed with depth dependent cell size to visualize the data. These grids are not meant for scientific analysis or navigation, but for overview purposes only.

Description: The International Bathymetric Chart of the Southern Ocean Version 2 (IBCSO v2) is a digital bathymetric model (DBM) for the area south of 50° S with special emphasis on the bathymetry of the Southern Ocean. IBCSO v2 has a resolution of 500 m × 500 m in a Polar Stereographic projection (EPSG: 9354). The total data coverage of the seafloor is 23.79% with a multibeam-only data coverage of 22.32%. The remaining 1.47% include singlebeam and other data. IBCSO v2 is the most authoritative seafloor map of the area south of 50°S. IBCSO is a regional mapping project of the General Bathymetric Chart of the Ocean (GEBCO) supported by the Nippon Foundation – GEBCO Seabed 2030 Project. GEBCO is a project under the auspices of the International Hydrographic Organization (IHO) and the Intergovernmental Oceanographic Commission (IOC) with the goal to produce the authoritative map of the world's oceans. The IBCSO Project is also an integral part of the Antarctic research community and an expert group of the Scientific Committee on Antarctic Research (SCAR). For further information about the IBCSO Project, please visit http://www.ibcso.org.

Description: Multibeam data were collected during RV Polarstern cruise ARK-XXIII/3 (2008-08-12 to 2008-10-17). Multibeam sonar system was Atlas Hydrographic Hydrosweep DS 2 multibeam echo sounder. Data are processed with Caris HIPS, including sound velocity correction with SV data from CTDs, tidal correction with TPXO9_atlas_v5 (https://www.tpxo.net/global/tpxo9-atlas), and manual cleaning. The soundings are combined in daily files, the format is XYZ ASCII (〈Lon〉 〈Lat〉 〈Depth in meters, positive up, relative to mean sea level〉). Additional blockmedian grids have been computed with depth dependent cell size to visualize the data. These grids are not meant for scientific analysis or navigation, but for overview purposes only.

Description: Bathymetry data was acquired during R/V MARIA S. MERIAN cruise MSM44 in the northeastern Baffin Bay between 30.06.2015 and 30.07.2015. The cruise carried out multidisciplinary research in order to investigate the deglaciation history of the Greenland Ice Sheet (GIS). To research the involved ocean, cryosphere and climate processes and feedbacks and to address the complex spatial and temporal distribution patterns of the marine GIS terminations in the northeast Baffin Bay, RV MARIA S. MERIAN visited sites in the Davis Strait, the Uumannaq Trough, and the Melville Bay during expedition MSM44. The objectives were to systematically search for and map glacigenic seafloor features providing information on the maximum extend and retreat histories of ice sheets since the last glacial maximum and during the Holocene. Extensive mapping was conducted due to the fact, that several huge parts of Greenland's coast are only insufficiently mapped or completely uncharted and thus are barely reliable in concern of navigation and interpretation towards glacigenic features of the last ice ages. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval. Description of processed data sources: During the MSM44 cruise, the hull-mounted KONGSBERG EM122 multibeam echosounder (MBES) was utilized to perform bathymetric mapping in medium to deep waters. Two linear transducer arrays in a Mills Cross configuration transmit acoustic signals of a nominal sonar frequency of 12 kHz. With 432 soundings per swath, the emission cone has a dimension of 150° across track and 2° along track. With a reception obtained from 288 beams, the actual beam footprint is 2° by 2°. Depending on the roughness of the seafloor and the water depth, the swath width on a flat bottom is maximum six times the water depth. For further information on the system, consult https://www.km.kongsberg.com/. The position and depth of the water column is estimated for each beam by using the detected two-way-travel time and the beam angle, ray-traced through the water column, utilizing a proper sound speed profile. Motion sensor data such as roll, pitch and heading as well as the time synchronization of the GPS clock and positioning via GPS were applied during data acquisition within the system, to ensure correct seafloor mapping. The multibeam surveys were generally run at 8 knots. During deep water surveys 〉500 m generally a swath angle of about 130° was used. In shallow water, the swath angles were set to a maximum of 150°. During the entire cruise two complete system break downs happened where a manual restart was performed. Responsible person during this cruise / PI: Laura Jensen & Simon Dreutter (simon.dreutter@awi.de) Description of data processing: Postprocessing and products were conducted by the Seafloor-Imaging & Mapping group of MARUM/FB5, responsible person Paul Wintersteller (seafloor-imaging@marum.de). The open source software MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, https://www.mbari.org/products/research-software/mb-system, 2017) was utilized for this purpose. Tide and a sound velocity profile were applied to the MSM44 data; there were no corrections for roll, pitch and heave. Using Mbeditviz, artefacts were cleaned manually. NetCDF (GMT) grids of the edited data as well as statistics were created with mbgrid. The published bathymetric EM122 grid of the cruise MSM44 has a resolution of 35 m. No total propagated uncertainty (TPU) has been calculated to gather vertical or horizontal accuracy. A higher resolution is, at least partly, achievable. The grid extended with _num represents a raster dataset with the statistical number of beams/depths taken into account to create the depth of the cell. The extended _sd -grid contains the standard deviation for each cell. The DTMs projections are given in Geographic coordinate system Lat/Lon; Geodetic Datum: WGS84. All grids produced are retrievable through the PANGAEA database (www.pangaea.de). Chief Scientist: Boris Dorschel CR: https://www.tib.eu/de/suchen/id/awi%3Adoi~10.2312%252Fcr_msm44/ CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2013/20130053.htm

Description: Multibeam data were collected during RV Maria S. Merian cruise MSM31. Multibeam sonar system was Kongsberg EM1002. Data are unprocessed and may contain outliers and blunders and should not be used for grid calculations and charting projects without further editing. The raw multibeam sonar data in Kongsberg multibeam processing format (*.all) were recorded with Kongsberg SIS software running on Windows operating system. Kongsberg data files can be processed using the software packages CARIS HIPS/SIPS or with the open source software package MB-System.

Description: Multibeam data were collected during RV Maria S. Merian cruise MSM31. Multibeam sonar system was Kongsberg EM122. Data are unprocessed and may contain outliers and blunders and should not be used for grid calculations and charting projects without further editing. The raw multibeam sonar data in Kongsberg multibeam processing format (*.all) were recorded with Kongsberg SIS software running on Windows operating system. Kongsberg data files can be processed using the software packages CARIS HIPS/SIPS or with the open source software package MB-System.

Description: Multibeam water column data were collected during RV Maria S. Merian cruise MSM31. Multibeam sonar system was Kongsberg EM122. The raw water column sonar data in Kongsberg format (*.wcd) were recorded with Kongsberg SIS software running on Windows operating system. Kongsberg wcd files can be processed using software packages like CARIS HIPS/SIPS, in combination with their corresponding bathymetry (*.all) files.

Description: Multibeam data were collected during RV Maria S. Merian cruise MSM44 (2015-07-01 to 2015-07-30). Multibeam sonar system was Kongsberg EM 122 multibeam echosounder. Data are processed with Caris HIPS, including sound velocity correction with SV data from SVPs, CTDs and World Ocean Atlas 13 (https://doi.org/10.7289/v5f769gt), tidal correction with TPXO9_atlas_v5 (https://www.tpxo.net/global/tpxo9-atlas), and manual cleaning. The soundings are combined in daily files, the format is XYZ ASCII (〈Lon〉 〈Lat〉 〈Depth in meters, positive up, relative to mean sea level〉). Additional blockmedian grids have been computed with depth dependent cell size to visualize the data. These grids are not meant for scientific analysis or navigation, but for overview purposes only.

Description: Global coupled climate models are in continuous need for evaluation against independent observations to reveal systematic model deficits and uncertainties. Changes in terrestrial water storage (TWS) as measured by satellite gravimetry missions GRACE and GRACE-FO provide valuable information on wetting and drying trends over the continents. Challenges arising from a comparison of observed and modelled water storage trends are related to gravity observations including non-water related variations such as, for example, glacial isostatic adjustment (GIA). Therefore, correcting secular changes in the Earth's gravity field caused by ongoing GIA is important for the monitoring of long-term changes in terrestrial water from GRACE in particular in former ice-covered regions. By utilizing a new ensemble of 56 individual realizations of GIA signals based on perturbations of mantle viscosities and ice history, we find that many of those alternative GIA corrections change the direction of GRACE-derived water storage trends, for example, from gaining mass into drying conditions, in particular in Eastern Canada. The change in the sign of the TWS trends subsequently impacts the conclusions drawn from using GRACE as observational basis for the evaluation of climate models as it influences the dis-/agreement between observed and modelled wetting/drying trends. A modified GIA correction, a combined GRACE/GRACE-FO data record extending over two decades, and a new generation of climate model experiments leads to substantially larger continental areas where wetting/drying trends currently observed by satellite missions coincide with long-term predictions obtained from climate model experiments.

Description: The Southern Ocean surrounding Antarctica is a region that is key to a range of climatic and oceanographic processes with worldwide effects, and is characterised by high biological productivity and biodiversity. Since 2013, the International Bathymetric Chart of the Southern Ocean (IBCSO) has represented the most comprehensive compilation of bathymetry for the Southern Ocean south of 60°S. Recently, the IBCSO Project has combined its efforts with the Nippon Foundation – GEBCO Seabed 2030 Project supporting the goal of mapping the world’s oceans by 2030. New datasets initiated a second version of IBCSO (IBCSO v2). This version extends to 50°S (covering approximately 2.4 times the area of seafloor of the previous version) including the gateways of the Antarctic Circumpolar Current and the Antarctic circumpolar frontal systems. Due to increased (multibeam) data coverage, IBCSO v2 significantly improves the overall representation of the Southern Ocean seafloor and resolves many submarine landforms in more detail. This makes IBCSO v2 the most authoritative seafloor map of the area south of 50°S.