Wind‐Driven Freshwater Export at Cape Farewell
Increased freshwater input to the Subpolar North Atlantic from Greenland ice melt and the Arctic could strengthen stratification in deep convection regions and impact the overturning circulation. However, freshwater pathways from the east Greenland shelf to deep convection regions are not fully unde...
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Veröffentlicht in: | Journal of geophysical research. Oceans 2022-05, Vol.127 (5), p.n/a |
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Sprache: | eng |
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Zusammenfassung: | Increased freshwater input to the Subpolar North Atlantic from Greenland ice melt and the Arctic could strengthen stratification in deep convection regions and impact the overturning circulation. However, freshwater pathways from the east Greenland shelf to deep convection regions are not fully understood. We investigate the role of strong wind events at Cape Farewell in driving surface freshwaters from the East Greenland Current to the Irminger Sea. Using a high‐resolution model and an atmospheric reanalysis, we identify strong wind events and investigate their impact on freshwater export. Westerly tip jets are associated with the strongest and deepest freshwater export across the shelfbreak, with a mean of 37.5 mSv of freshwater in the first 100 m (with reference salinity 34.9). These wind events tilt isohalines and extend the front offshore, especially over Eirik Ridge. Moderate westerly events are associated with weaker export across the shelfbreak (mean of 15.9 mSv) but overall contribute to more freshwater export throughout the year, including in summer, when the shelf is particularly fresh. Particle tracking shows that half of the surface waters crossing the shelfbreak during tip jet events are exported away from the shelf, either entering the Irminger Gyre, or being driven over Eirik Ridge. During strong westerly wind events, sea ice detaches from the coast and veers toward the Irminger Sea, but the contribution of sea ice to freshwater export at the shelfbreak is minimal compared to liquid freshwater export due to limited sea ice cover at Cape Farewell.
Plain Language Summary
The Atlantic circulation brings warm surface waters from the tropics to the poles, where deep, cold waters are formed and brought back to the tropics, thus redistributing heat across the Atlantic. Climate change leads to increased melt of the Greenland ice sheet and a freshening of the Arctic Ocean. If this additional freshwater reaches regions where deep waters are formed, it could weaken this deep water formation and consequently the Atlantic circulation. Since this could lead to large‐scale climate impacts, we need to better understand the pathways between freshwater sources and these regions. The present study investigates wind‐driven freshwater export from the east Greenland shelf to the Irminger Sea, southeast of Greenland. We find that strong westerly winds are associated with surface waters export offshore, with part of the exported waters entering the Irminger Sea. H |
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ISSN: | 2169-9275 2169-9291 |
DOI: | 10.1029/2021JC018309 |