Abstract

During the upwelling season along the coast off central Chile (33-40S), cold upwelled water can be easily distinguished from warm oceanic water using satellite infrared images. The boundary between cold and warm surface waters is a relatively narrow region with large horizontal gradients, denominated upwelling front, which is also clearly visible in satellite images. Here, using daily NOAA satellite infrared images from the period 1998-2000, we described the spatial distribution of mesoscale features related to upwelling fronts. Together with infrared data, we use SeaWiFS's color images to explore the relationship between Chlorophyll concentration and thermal upwelling fronts. Our results show that thermal fronts have maximum intensities (0.2C/km) in spring and summer and they are typically located between 30 and 300 km off the coast. The offshore extension of the upwelling front was usually larger between 35-37S, related to the presence of a large anticyclonic eddy in this region during the warm season. In general, chlorophyll was well correlated (inversely) to SST showing similar offshore variability scale and covariance in mesoscale features like eddies and filaments