Sea‐ice melt driven by ice‐ocean stresses on the mesoscale
Name
Eddy_Ice_Pumping_rev1.pdf
Description
Accepted version
Size
875.75 KB
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Unknown
Checksum (MD5)
274a4d8b80018052cd0da5bf96ccdcc0
Author(s)
Gupta, Mukund
Marshall, John
Song, Hajoon
Campin, Jean-Michel
Meneghello, Gianluca
Date Issued
November 2020
Journal
Journal of Geophysical Research: Oceans
Publisher
American Geophysical Union (AGU)
Version
Author's final manuscript
Abstract
The seasonal ice zone around both the Arctic and the Antarctic coasts is typically characterized by warm and salty waters underlying a cold and fresh layer that insulates sea-ice floating at the surface from vertical heat fluxes. Here, we explore how a mesoscale eddy field rubbing against ice at the surface can, through Ekman-induced vertical motion, bring warm waters up to the surface and partially melt the ice. We dub this the “Eddy-Ice-Pumping” (EIP) mechanism. When sea-ice is relatively motionless, underlying mesoscale eddies experience a surface drag that generates Ekman upwelling in anticyclones and downwelling in cyclones. An eddy composite analysis of a Southern Ocean eddying channel model, capturing the interaction of the mesoscale with sea-ice, shows that within the compact ice zone, the mixed layer depth (MLD) is shallow in anticyclones (∼20 m) due to sea-ice melt and deep in cyclones (∼50–200m) due to brine rejection. “EIP” warms the core of anticyclones without significantly affecting the temperature of cyclones, producing a net upward vertical heat flux that reduces the mean sea-ice thickness by 10% and shoals the MLD by 60% over the course of winter and spring. In the following months, the sea-ice thickness recovers with an overshoot, due to strong negative feedbacks associated with atmospheric cooling and salt stratification. Consequently, the effect of “EIP” does not accumulate over the years, but modulates the seasonal cycle of ice within the compact ice zone.
MIT Department
Massachusetts Institute of Technology. Program in Atmospheres, Oceans, and Climate
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1029/2020JC016404
