Variability and dynamics of along-shelf exchange in the west Antarctic Peninsula (wAP)
The analysis of a 2-year run (2009-2010) reveals a pronounced seasonal cycle of along-shelf exchange in the BS-CwAP system, modulated by the interplay between cold Weddell-sourced water inflow around BS and modified Circumpolar Deep Water (mCDW)from CwAP. In winter/spring, there is a net flux of cold BS water towards the CwAP. This largely reverses in summer/fall, with a net flow of warm water towards BS from the CwAP. The exchange occurs in the form of narrow, bottom-trapped buoyant currents forced in several gaps between islands separating BS and the CwAP. The seasonal variation of the along-shelf exchange seems to be driven by the wind forcing modulating the inflow of Weddell water into BS. The model results are consistent with several key observed features in the hydrographic structure.
Our results suggest a fairly dynamic thermal gradient along the wAP, with the cold/warm boundary moving about 300 km along the coast throughout the year, and narrow cold/warm intrusions extending far from one basin to the other. The implications for our understanding of glacier retreat along the wAP shelf are discussed.