Temporal evolution of under-ice meltwater layers and false bottoms and their impact on summer Arctic sea ice mass balance
Bibliographic Data
Low-salinity meltwater from Arctic sea ice and its snow cover accumulates and creates under-ice meltwater layers below sea ice. These meltwater layers can result in the formation of new ice layers, or false bottoms, at the interface of this low-salinity meltwater and colder seawater. As part of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate (MOSAiC), we used a combination of sea ice coring, temperature profiles from thermistor strings and underwater multibeam sonar surveys with a remotely operated vehicle (ROV) to study the areal coverage and temporal evolution of under-ice meltwater layers and false bottoms during the summer melt season from mid-June until late July. ROV surveys indicated that the areal coverage of false bottoms for a part of the MOSAiC Central Observatory (350 by 200 m2) was 21%. Presence of false bottoms reduced bottom ice melt by 7–8% due to the local decrease in the ocean heat flux, which can be described by a thermodynamic model. Under-ice meltwater layer thickness was larger below first-year ice and thinner below thicker second-year ice. We also found that thick ice and ridge keels confined the areas in which under-ice meltwater accumulated, preventing its mixing with underlying seawater. While a thermodynamic model could reproduce false bottom growth and melt, it could not describe the observed bottom melt rates of the ice above false bottoms. We also show that the evolution of under-ice meltwater-layer salinity below first-year ice is linked to brine flushing from the above sea ice and accumulating in the meltwater layer above the false bottom. The results of this study aid in estimating the contribution of under-ice meltwater layers and false bottoms to the mass balance and salt budget for Arctic summer sea ice
Antarctic sea ice · Arctic · Arctic ice pack · Climatology · Cryosphere · Fast ice · Geomorphology · Ice divide · Ice shelf · Iceberg · Melt pond · Meltwater · Sea ice · Sea ice thickness · Snow · Arctic and Antarctic ice dynamics · Climate change and permafrost · Cryospheric studies and observations · Geology · Oceanography
The Eurasian Arctic Ocean along the MosaiC drift in 2019–2020
Overview of the MosaiC expedition
The MosaiC Distributed Network
Snowmelt contribution to Arctic first-year ice ridge mass balance and rapid consolidation during summer melt
Different mechanisms of Arctic first-year sea-ice ridge consolidation observed during the MosaiC expedition
Thin and transient meltwater layers and false bottoms in the Arctic sea ice pack—Recent insights on these historically overlooked features
Characteristics and sources of fluorescent aerosols in the central Arctic Ocean
Sea ice mass balance during the MosaiC drift experiment
Farthest north
Spatiotemporal evolution of melt ponds on Arctic sea ice
Quantifying false bottoms and under-ice meltwater layers beneath Arctic summer sea ice with fine-scale observations
Sea ice and snow characteristics from year-long transects at the MosaiC Central Observatory
Overview of the MosaiC expedition
Meteorological conditions during the MosaiC expedition
Overview of the MosaiC expedition
Seasonality and timing of sea ice mass balance and heat fluxes in the Arctic transpolar drift during 2019–2020
| Unique citing works | 8 |
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