The wind driven spin-up of the Beaufort Gyre from satellite radar altimetry
Abstract
The Arctic Ocean contains >70,000 km3 of liquid freshwater, which if released, even in part, has the potential to disrupt the global thermohaline circulation and cool the climate of Northern Europe. Spatially and temporally limited observations show the freshwater content of the Arctic Ocean has increased over the last few decades, predominantly in the Western Arctic/Beaufort Gyre region, and that freshwater entering the North Atlantic decreased by a similar amount. Modelling experiments suggest that Ekman convergence is a key driver of fresh water accumulation, but there have been no observations of either the change in sea surface height (SSH), or halocline depth, associated with this mechanism. We present continuous satellite measurements of SSH between 1995 and 2010 from the ERS-2 and Envisat satellites. We observe a positive SSH trend that increases the geostrophic velocity across the gyre. We show the trend in the wind field curl has a corresponding spatial pattern, indicating that Ekman convergence controls freshwater variability. Using our data, we estimate the increase in freshwater content over the Western Arctic between 1995 and 2010. Further, our results suggest that the changing sea ice cover might be enhancing this spin-up.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.C52B..01G
- Keywords:
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- 0750 CRYOSPHERE / Sea ice;
- 0758 CRYOSPHERE / Remote sensing;
- 4207 OCEANOGRAPHY: GENERAL / Arctic and Antarctic oceanography