CONICET | Buscador de Institutos y Recursos Humanos

Twelve years of daily satellite data were used to study the temporal variability of the sea surface temperature (SST) over the Northern Argentinean Continental Shelf (NACS; between 33-45 S and 52-66 W). The seasonal cycle, which includes the annual and semi-annual signals, was assessed using harmonic analysis. The annual cycle explained more than 90% of the total variance in the NACS, with SST amplitudes varying from 3.4 to 7.6 C. Largest variances values for this time scale were observed along the Argentinean coast and the inner shelf; particularly in the El Rincón region (exceeding 96%). The NACS experienced weak inter-annual variability, with variances less than 2%, and the variability at intra-annual scales accounted for around 8% of the variance. Empirical Orthogonal Function Analysis (EOF ) was applied to daily SST anomalies in the annual timescale, indicating that nearly 94% of its variance was explained by the first two modes, which accounted for 70 and 24% of the variance, respectively. Mode 1 prevailed most of the year with its positive phase occurring in autumn/winter and the negative in spring/summer. This mode revealed the seasonal radiative warming/cooling, related to the heating/cooling in summer/winter in most of the region; the shallow waters of the Río de la Plata and El Rincón were heated and cooled more and faster than deeper waters. The weakest seasonal heating/cooling occurred around Península Valdés, where vertical mixing maximizes due to tidal action. Mode 2 corresponded to early spring and early fall in their positive and negative phases, respectively. This mode was related to a transition during the early intermediate seasons when the cooling/heating of an extended coastal region connecting Península Valdés and the Río de la Plata occur.

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