Stirring of Sea‐Ice Meltwater Enhances Submesoscale Fronts in the Southern Ocean
| Autor: | Andrew F. Thompson, Isabelle Giddy, Sebastiaan Swart, M.A. Du Plessis, Sarah-Anne Nicholson |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Subduction Mixed layer Mesoscale meteorology Marginal ice zone Stratification (water) Oceanography 01 natural sciences Geophysics Eddy Space and Planetary Science Geochemistry and Petrology Earth and Planetary Sciences (miscellaneous) Sea ice Meltwater Geology 0105 earth and related environmental sciences |
| Zdroj: | Journal of Geophysical Research: Oceans Volume 126, Issue 4 |
| Popis: | In the sea ice-impacted Southern Ocean, the spring melt of sea ice modifies the upper ocean. These modified waters subduct and enter the global overturning circulation. Submesoscale processes act to modulate the stratification of the mixed layer and therefore mixed layer properties. Sparse observations mean that the role of submesoscales in exchange across the base of the mixed layer in this region is not well constrained. The goal of this study is to determine the interplay between sea ice melt, surface boundary layer forcing, and submesoscale flows in regulating the mixed layer structure in the Antarctic Marginal Ice Zone. High-resolution observations suggest that fine-scale lateral fronts, representative of submesoscale mixed layer eddies (MLEs), arise from mesoscale gradients produced by northwards advecting sea ice meltwater. The strong salinity-driven stratification at the base of the mixed layer confined the MLEs to the upper ocean, limiting submesoscale vertical fluxes across the mixed layer base. This strong stratification prevents the local subduction by submesoscale flow of these modified waters, suggesting that the subduction site that links to the global overturning circulation does not correspond with the location of sea ice melt. However, the presence of MLEs enhanced the magnitude of lateral gradients through stirring and increased the potential for Ekman-driven cross-frontal flow to modulate the stability of the mixed layer and mixed layer properties. The inclusion, particularly of submesoscale Ekman Buoyancy Flux parameterizations, in coupled-climate models, may improve the representation of mixed layer heat and freshwater transport in the ice-impacted Southern Ocean during summer. |
| Databáze: | OpenAIRE |
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