Open AccessOn the relationship between satellite‐retrieved surface temperature fronts and chlorophyll a in the western South Atlantic
Author(s) -
Saraceno Martin,
Provost Christine,
Piola Alberto R.
Publication year - 2005
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004jc002736
Subject(s) - seawifs , sea surface temperature , mesoscale meteorology , climatology , front (military) , ocean color , polar front , oceanography , eddy , satellite , geology , isopycnal , buoy , mixed layer , environmental science , phytoplankton , geography , meteorology , physics , turbulence , chemistry , organic chemistry , astronomy , nutrient
The time‐space distribution of chlorophyll a in the southwestern Atlantic is examined using 6 years (1998–2003) of sea surface color images from Sea‐viewing Wide Field of View Sensor (SeaWiFS). Chlorophyll a (chl a ) distribution is confronted with sea surface temperature (SST) fronts retrieved from satellite imagery. Histogram analysis of the color, SST, and SST gradient data sets provides a simple procedure for pixel classification from which eight biophysical regions in the SWA are identified, including three new regions with regard to Longhurst (1998) work: Patagonian Shelf Break (PSB), Brazil Current Overshoot, and Zapiola Rise region. In the PSB region, coastal‐trapped waves are suggested as a possible mechanism leading to the intraseasonal frequencies observed in SST and chl a . Mesoscale activity associated with the Brazil Current Front and, in particular, eddies drifting southward is probably responsible for the high chl a values observed throughout the Brazil Current Overshoot region. The Zapiola Rise is characterized by a local minimum in SST gradient magnitudes and shows chl a maximum values in February, 3 months later than the austral spring bloom of the surroundings. Significant interannual variability is present in the color imagery. In the PSB, springs and summers with high chl a concentrations seem associated with stronger local northerly wind speed, and possible mechanisms are discussed. Finally, the Brazil‐Malvinas front is detected using both SST gradient and SeaWiFS images. The time‐averaged position of the front at 54.2°W is estimated at 38.9°S and its alongshore migration of about 300 km.