Séminaire "Glacial melt in Antarctic" | 6 mai 2013

Evidence of accelerating glacial melt in Antarctic coastal sea level rise
Alberto Naveira Garabato
National Oceanography Center, Southampton (Royaume-Uni)

The subpolar Southern Ocean is a region of great climatic importance, hosting intense air - sea - ice interactions with far-reaching consequences for global ocean circulation and sea level. Glaciological measurements suggest that these interactions may be undergoing a profound change as a result of an accelerating glacial discharge into the Antarctic coastal seas, yet current evidence of this change is suggestive at best. In this work, we analyse the altimetric record of sea surface height (SSH) during the largely ice-free summer season to show that the subpolar Southern Ocean has experienced a pronounced, quasi-circumpolar positive trend in summertime SSH of 1 mm / yr above the global-mean sea level rise since the early 1990s. The signal is generally amplified near the coast and in the Pacific sector, is broadly consistent in magnitude and geography with in situ observations of upper-ocean freshening in several sectors of the Antarctic shelf seas, and exhibits a magnitude that will be shown to be consistent with that implied by glaciological measurements of the accelerating glacial discharge. All in all, our analysis indicates that the widespread sea level rise in the subpolar Southern Ocean primarily reflects a halosteric response to the recent acceleration in Antarctic ice mass loss on decadal time scales, although wind forcing plays a significant role in explaining SSH variability on interannual and shorter time scales.

Lundi 6 mai 2013 à 11h
LGGE, bâtiment OSUG-A, salle Manuel Forestini