C039-02
Snow depth on the MOSAiC floe from autumn to spring: Continuous point measurements vs. weekly snow distributions

Friday, 11 December 2020: 05:34
Virtual
Julia Regnery1, Stefanie Arndt2, Marcel Nicolaus3, Stefan Hendricks2, Glen E Liston4, Marc Oggier5, Polona Itkin6, Matthias Jaggi7, Robert Ricker2, Melinda Webster5, H. Jakob Belter2, Mario Hoppmann8 and Donald K Perovich9, (1)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Potsdam, Potsdam, Germany, (2)Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany, (3)Alfred Wegener Institute, Bremerhaven, Germany, (4)Colorado State University, Cooperative Institute for Research in the Atmosphere (CIRA), Fort Collins, CO, United States, (5)University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK, United States, (6)UiT The Arctic University of Norway, Tromsø, Norway, (7)WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland, (8)Alfred-Wegener-Institute, Oldenburg, Germany, (9)USA CRREL, Hanover, NH, United States
Recorded Presentation
Abstract:
Snow depth is one of the sea ice Essential Climate Variables, as it controls the energy and momentum fluxes across the interfaces between the atmosphere, sea ice and ocean. At the same time, it actively modifies the overall sea-ice mass budget by, e.g. the seasonal formation of superposed and snow ice. However, area-wide snow depth is one of the least known and most difficult to observe parameters of the Arctic and Antarctic sea-ice cover. This is mainly due to its exceptionally high spatial and temporal variability and the lack of accurate observational techniques to retrieve snow depth at the kilometer scale and larger, which is needed for integration and better climate understanding in models.

The “Multidisciplinary drifting Observatory for the Study of Arctic Climate” (MOSAiC) gave the unique opportunity to compare continuous time-series of snow depth evolution at fixed locations using autonomous instruments and weekly transect measurements along fixed paths. These measurements covered a wide variety of ice types and surface conditions.

In our study, the transect measurements showed a snow depth ranging from 0.1 to 0.5 m (between 10th and 90thpercentile) on seasonal sea ice, with an average value of 0.27 m prior to the melt season in early May. The fixed-location measurements from 4 deployed Snow Buoys revealed snow depths between 0.1 and 0.2 m in the same time-frame.

Our results indicate that newly fallen snow becomes redistributed by the wind and preferentially deposited near raised topographic features such as ridges and in surface depressions such as refrozen leads. Thus, in early May, 9% of the snow measurements along the 1.5 km transect loop on seasonal ice indicated snow depth values smaller than 10 cm, which can be related to refrozen leads. In contrast, about 19% of the snow depth values are higher than 30 cm.

A more detailed analysis of the combined sea-ice and snow thickness data sets along the MOSAiC transect lines will give valuable insights into the snow volume budget and its quantitively relation to the surface topography. This knowledge gain will advance numerous interdisciplinary studies of snow on sea ice, in particular those with links to numerical simulations and remote sensing applications.

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