Spatial snow and ice thickness measurements from ice stations PS81/503, PS81/506 and PS81/517 from Research Vessel Polarstern in the Antarctic Weddell Sea in austral winter 2013 (cruise leg ANT-XXIX/6, AWECS campaign). Terrestrial laser scanning (TLS) was used to determine the snow surface height above sea level for an approximately 50x50m patch. The reference to sea level was obtained using registration targets drilled through the ice with a measured distance between the target and the water level in the drill holes. Magnaprobe measures snow depth (Sturm et al., 2018) and the GEM-2 instrument measures the combined snow and ice thickness (Hunkeler et al., 2016). Magnaprobe and GEM-2 was performed inside the laser scan field after all scans had been acquired. Additionally floe-scale walks were performed using Magnaprobe and GEM-2 to capture variability on a larger scale than the laser scan field. Further information can be found in Wever et al. (2021).

Summary: ======== (1) snow surface above sea level from Terrestrial Laser Scanning (TLS) (2) snow depth from Magnaprobe (MP), see Sturm and Holmgren (2018) for details. (3) combined snow and ice thickness from a multifrequency electromagnetic induction instrument (GEM-2), see Hunkeler et al. (2015) for details. For each floe, two sets of measurements were performed: (1) in a designated area, terrestrial laser scanning (TLS), magnaprobe, and GEM-2 was used to map snow and ice thickness in high spatial resolution. (2) to sample a larger area, a floe-scale walk (FSW) was performed using Mangaprobe and GEM-2.---Coordinates:============X and Y coordinates are relative to a GPS base station installed on each floe. Coordinates were determined using post-processing kinematic GPS (PPK-GPS), and corrected for floe ration and drift. Coordinates of measurements inside the laser scanning area were particularly carefully processed to collocate measurements as accurately as possible (within a few cm). The vertical height above sea level in the TLS data was determined by using reflectors on poles. Upon installation of these reflector poles, the ice was drilled through and the height of the reflector above sea level was determined. For details, see Wever et al. (2021).On the floe scale walk, magnaprobe coordinates have been equally processed as in the laser scanning area. However, for the GEM-2 instrument, the position of the magnaprobe was taken for the corresponding time stamp in the GEM-2 data. Since the GEM-2 instrument was following the Magnaprobe surveyor with a few m distance, this leads to less precise positioning. However, the GEM-2 instrument also has a footprint of similar order of magnitude (see Hunkeler et al., 2015).Coordinate reference points:============================All coordinates are relative to GPS base station 1, in a local coordinate system where X and Y coordinates align with easting and northing, respectively, from the respective UTM Zone at a specific point in time. Below are listed the respective locations of GPS base station 1 for each ice station which defines the local coordinate system:For PS81/503: Location of GPS base station 1, July 8 2013, 1646 UTC:WGS84 : latitude=-67.188921 longitude=-13.219895 UTM Zone 28S : northing=2546456 easting=577005For PS81/506: Location of GPS base station 1, July 12 2013, 2000 UTC:WGS84 : latitude=-67.19689 longitude=-23.15692UTM Zone 27S : northing=2545052 easting=406729For PS81/517: Location of GPS base station 1, July 31 2013, 1942 UTC:WGS84 : latitude=-63.39434 longitude=-51.13041UTM Zone 22S : northing=2970466 easting=493483