Projection and uncertainties of sea level trends in Baixada Santista

Abstract

The main factors that produce variations in sea level are: wind, through friction on the surface of the sea, in the form of surface waves and currents; atmospheric pressure; astronomical effects, associated with the relative positions of Earth, Sun and Moon. Other complementary factors also affect the sea level: eustasy, an effect dependent on the volume of water in the global ocean; steric effects, resulting from the variation of the volume of the water; halosteric effects, associated with salinity variations; isostasy, varying the average level of the sea due to changes in the position of the seabed and the topography of the coasts; local variations of the Earth's gravity field. The mean sea level in Santos has great variability, so that a large number of complete years should be considered for assessing the real sea level trend, because several long period periodicities are present in the records; the computed trends show great variations, and some decades have a definite decreasing trend of mean sea level; yet, earlier decades tend to have lower trends than recent ones, so the rise in mean sea level can be considered to accelerate over time.