CONICET | Buscador de Institutos y Recursos Humanos

The purpose of the present work is to characterize the length scales of the spatio/temporal variability of the Sea Surface Temperature (SST) in the Southwestern Atlantic (SWA) using robust statistical measurement of two-dimensional autocorrelation of the SST fields. We present the results of the analysis of two years of 5 days composite of Advanced Very High Resolution Radiometer SST images with a spatial resolution of 4 km. For each image we computed the autocorrelation ellipses, defined by the length scale of maximum correlation of the major axis. Results are then averaged seasonally and yearly. By calculating decorrelation scales from individual images and then averaging these, information about extent and position of small scale features is preserved, in opposition to what happened with the average of SST images. The regional variations in spatial scales and preferred orientation of the correlation ellipses clearly characterize major circulation features in the SWA. For example, the 2-years mean of the major axis of the ellipses shows an organized pattern with high values over the Malvinas Current and a disorganized pattern with relatively low values in the recirculation region of the Brazil Current. These patterns suggest a low and a high degree of spatial variability respectively. The standard deviation of the major axis indicates that a narrow region that precisely follows the continental shelf-break present very low values. Between 41oS and 42oS, in a region over the shelf and adjacent to the continental shelf-break, a spot of high standard deviation values is observed. It is suggested that this may reflect the exchange of waters across the shelf-break which has also been suggested by recent in-situ current measurements. Quantifying the dominant spatial scales of patterns in high resolution SST data will assist interpretation of other satellite data with lower spatial resolution as Sea Surface Height (SSH) and in situ moored data.

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