Sea surface temperature anomalies on the Western South Atlantic from 1982 to 1994

Thirteen years of weekly sea surface temperature (SST) fields derived from satellite data (January 1982–December 1994) are used to investigate spatial and temporal variabilities of SST in the western region of the South Atlantic Ocean. The analysis is focused on the large-scale variations over the continental shelf and slope region with depths less than 1000 m, between 42 and 22°S. Within the 13-year span, a total of 13 cold and seven warm SST anomalies are observed during and right after ENSO onset. Northward-propagating cold and warm anomalies have average speeds of the order of 18 and 14 cm/s, respectively. Southward-advected cold and warm anomalies, on the other hand, have slower speeds. From a principal component analysis, the first two modes for the inner along-shelf transect, which account for more than 65% of the total non-seasonal variance, suggest a tendency for cold SST anomalies (SSTAs) to be related to ENSO events. Possible connections between SSTAs and the Southern Oscillation Index are also explored. Consideration of the SSTA analyses seem to confirm the hypothesis that the anomalous cold (warm) water extensions to the north on the shelf occur generally in every warm (cold) ENSO+1 year in the present climatology