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Precise measurements of Arctic sea ice mass balance are necessary to understand the rapidly changing sea ice cover and its representation in climate models. During the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, we made repeat point measurements of snow and ice thickness on primarily level first- and second-year ice (FYI, SYI) using ablation stakes and ice thickness gauges. This technique enabled us to distinguish surface and bottom (basal) melt and characterize the importance of oceanic versus atmospheric forcing. We also evaluated the time series of ice growth and melt in the context of other MOSAiC observations and historical mass balance observations from the Surface Heat Budget of the Arctic (SHEBA) campaign and the North Pole Environmental Observatory (NPEO). Despite similar freezing degree days, average ice growth at MOSAiC was greater on FYI (1.67 m) and SYI (1.23 m) than at SHEBA (1.45 m, 0.53 m), due in part to initially thinner ice and snow conditions on MOSAiC. Our estimates of effective snow thermal conductivity, which agree with SHEBA results and other MOSAiC observations, are unlikely to explain the difference. On MOSAiC, FYI grew more and faster than SYI, demonstrating a feedback loop that acts to increase ice production after multi-year ice loss. Surface melt on MOSAiC (mean of 0.50 m) was greater than at NPEO (0.18 m), with considerable spatial variability that correlated with surface albedo variability. Basal melt was relatively small (mean of 0.12 m), and higher than NPEO observations (0.07 m). Finally, we present observations showing that false bottoms reduced basal melt rates in some FYI cases, in agreement with other observations at MOSAiC. These detailed mass balance observations will allow further investigation into connections between the carefully observed surface energy budget, ocean heat fluxes, sea ice, and ecosystem at MOSAiC and during other campaigns.
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Sea ice thickness and false bottom measurements along drill lines during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, Leg 4
This dataset contains measurements of sea ice thickness along drill lines. These measurements were taken in the Central Arctic during Leg 4 of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition, July 14-29, 2020. Thickness measurements include observations of rafted ice, false bottoms, and sea ice freeboard. Measurements were made through holes in the ice made with a 2-inch sea ice drill, with thickness and features observations made using a combination of thickness tape and a snow stick adapted for the purpose. The primary aim of these observations was to capture the presence and distribution of false bottom features under the ice during the melt season.
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- Award ID(s):
- 1724467
- PAR ID:
- 10389913
- Publisher / Repository:
- NSF Arctic Data Center
- Date Published:
- Subject(s) / Keyword(s):
- sea ice thickness MOSAiC
- Format(s):
- Medium: X Other: text/xml
- Sponsoring Org:
- National Science Foundation
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