Influência de sistemas de vento no deslocamento de água frias na Plataforma Continental Brasileira, utilizando dados AVHRR/NOAA / Influence of Systems of Wind in the Displacement of Cold Waters in the Brazilian Continental Platform, Using AVHRR/NOAA data

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

An important oceanographic phenomenon observed in the SE/S Brazilian and Uruguayan coasts is the northward intrusion of a surface cold water tongue during the autumn and winter seasons. Past studies indicate that these intrusions have their origin as a combination of La Plata river outflow and the inshore and northward penetration of Malvinas water over the outer shelf of La Plata estuary. During the austral winter it reaches the lowest latitudes, being found in extreme cases as the year of 1993, in the southern coast of Rio de Janeiro. This seasonal cold water intrusion, presents an interannual variability. Numerical simulation studies indicate that winds from the north (south) have the effect of blocking (enhancing) the advance of the intrusion. With the intention of verifying possible correlations between the wind fields with the dynamics of these cold water intrusions, we analyze in this work an AVHRR-NOAA SST data set together with NCEP and DHN meteorological coastal winds. SST and wind time series were used for the months of May, June, July and August of the years of 1993 and 1995. From each SST digital map 22 zonal profiles were extracted from the coastline up to the shelf break spanning all the region. From each SST zonal profile we chose the smallest temperature as the indicator of the cold intrusion. Time lagged correlation was then calculated between each of these SST time series with NCEP wind time series of 5 points along the coastal region of the study area. A second method was to analyze the position of the 17 °C isotherm, established as an indicator of the front limit of cold waters. A correlation was also done between this isotherm position and wind time series. The obtained results did not however indicate a significant and clear correlation between the wind and SST variability. We speculate that this is due mainly to the fact that the influence of the winds on the surface circulation over the continental shelf is indirect. Moreover, it seems that the cold intrusion could be mostly controlled by the variability of the fresh water outflow , and the Malvinas waters availability over the outer shelf of the La Plata estuary with the synoptic wind variability being a minor factor.

ASSUNTO(S)

remote sensing centro nacional para predição ambiental (ncep) plataforma continental brasileira avançado de alta resolução(avhrr) temperatura da superfície do mar (tsm) oceanography oceanografia sea surface tempature (tsm) noaa radiaometro advanced very high resolution radiometer (avhrr) national center for environment prediction (ncep) ventos winds sensoriamento remoto

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