Physical Changes in the Patagonian Shelf

Abstract

The Patagonian shelf is one of the most productive and dynamic continental shelves of the world. Changes in the environmental conditions affect productivity, species population sizes, and community structure within the coastal ocean ecosystem. In this chapter, the baseline knowledge of the physical processes and the observed and expected changes that affect the Patagonian shelf and in particular the coastal area are reviewed. Sea surface temperature (SST) data show a significant positive trend north of ~50°S and negative trend values south of 50°S. The negative SST trend observed is associated with the positive trend observed in the dominant westerly winds within those latitudes. Chlorophyll a shows a linear trend during spring as large as 2 mg m−3 over a 10-year period in the southern portion of the continental shelf. The linear trend in sea surface height (SSH) ranges between 2 and 5 mm yr−1. In the northern region, the SSH trend is associated with local changes in the density field caused by advective effects in response to a southward displacement of the South Atlantic High. The Southern Annular Mode (SAM) is one of the main drivers that might explain a portion of the interannual variability observed in the Patagonian shelf.