Sobre a Variabilidade do Nível Médio do Mar na Costa Sudeste do Brasil

Abstract

Works on the mean sea level (MSL) and its relation to meteorological variables measured in ports of the southeastern region of Brazil are reviewed. Data from ports of north and northeast Brazil as well as Atlantic and Pacific coastal ports of South America, in which the southeastern region of Brazil is included, are also reviewed. The mean daily sea levels from Paranaguá to Santos vary in a similar way and are excited by the passage of atmospheric frontal systems. Periodicities of 3 to 6 days are observed in the time series of currents, temperature and salinity of the waters of the continental shelf of the region. The mean monthly levels from Piraquera (Ilha Grande Bay), Ubatuba, Santos and Cananéia have a similar variation and show 4 maxima during the year; in February, April-May, August and November. The February peak is strongly related to the seasonal solar heating while that of April-May is apparently caused by the action of the winds that displace the Tropical waters against the coast in this epoch of the year. The secondary peaks of August and November are apparently more associated with the oceanic variations that show a strong interannual variability. The seasonal mean sea level variation on the southeastern coast is similar to the ports of Recife, Salvador and Imbituba. The MSL's of the northern coast seem to have a different seasonal behavior from those of the southeastern coast. The long term sea level shows an accentuated increase in the more recent years, from the absolute value of the regression coefficients. The mean value of the secular variation calculated for the southeastern coast is about 30cm/century, with a "background" of the order of 10cm/century, from the variation along the South American coasts and the Atlantic coast of Africa.