Bipohysical provinces and surface fronts in the western south atlantic

SARACENO, M., C. PROVOST, AND A. PIOLA

Paris, France

Simposio; 35th COSPAR Scientific Assembly; 2004

Biophysical Provinces in the Western South Atlantic are studied using 6 years (1998-2003) of sea surface color images from SeaWiFS and 10 years (1986-1995) of AVHRR data. Based on histogram analysis of monthly climatologies of both data sets the space-time variations of the limits of the Biophysical Provinces are investigated. The Zapiola Rise shows up as a local minimum in SST gradient magnitude and shows chlorophyll-a concentration values that are out of phase with the surroundings (minimum in austral spring). This result suggests that the corresponding region should be recognized as an independent Province from the South Subtropical Convergence Province. In addition, the motion of the Brazil-Malvinas is focused out. The surface expression of the Brazil-Malvinas front, present in both SST and SeaWiFS images is centered at 38∞S. The surface front remains at the same location all year round with a north-south orientation, except in summer when it tends to pivot and have an east-west direction. This pivotal motion in summer leads to a 250 km long migration along the 1000 m isobath. The Brazil-Malvinas frontal motion is confronted to different model outputs.