APPLICATIONS OF SATELLITE INFORMATION TO STUDY FRONTAL REGIONS IN THE ARGENTINEAN CONTINENTAL SHELF (ACS)

ANDRÉS L. RIVAS; ANA I. DOGLIOTTI; JUAN P. PISONI; DOMINGO A. GAGLIARDINI

Puerto Madryn, Chubut. Argentina

Workshop; 4th Aquarius/SAC-D Science Workshop; 2008

Comisión Nacional de Actividades Espaciales (CONAE)

Surface thermal fronts cover relatively small areas which are characterized by sharp horizontal gradient of the sea surface temperature (SST). In the Argentinean Continental Shelf (ACS) these fronts define regions with different degree of vertical mixing. The proximity of water masses with different stability may supply nutrient to the illuminated layer thus enhancing primary production. The use of satellite information to identify and analyze these frontal systems has a series of advantages: they provide data with high spatial resolution (1 km) at high repeat frequency (1 day), they allow the analysis of physical (like SST) as well as biological (like chlorophyll concentrations as an index of the phytoplankton biomass) variables with the same spatial and temporal resolution, and the currently existing satellite data allows the analysis of their interannual variability. Here we present the main results of three studies that help characterizing the thermal fronts present in the ACS using remotely sensed data. In the first study the seasonal distribution of satellite-derived chlorophyll concentration (Chl-a), using SeaWiFS data, was analyzed and evidences of the influence of thermal fronts on the location of regions with high Chl-a were found (Seasonal variability in satellite-measured surface chlorophyll in the Patagonian Shelf. A.L. Rivas, A.I. Dogliotti and D.A. Gagliardini. Continental Shelf Research, 26, 2006, 703:720). A second study tried to quantify the influence of the identified thermal fronts on its biological activity using satellite information from AVHRR (SST) and SeaWiFS (Chl-a) sensors. It was estimated that the area affected by the presence of a physical front cover less than 15% of the total surface, but contribute with approximately 24% of the surface phytoplankton annual mean biomass (Quantitative estimation of the influence of surface thermal fronts over chlorophyll concentration at the Patagonian Shelf. A. L. Rivas. Journal of Marine Systems, 63, 2006, 183:190). Finally, the third study (in preparation) analyzes the thermal fronts and its seasonal distribution (using satellite SST data); it identifies the mechanisms that influence their development and interprets the vertical structure of the water column.