Transporte de volume e condições hidrográficas no Canal de São Sebastião

Abstract

Current data obtained using an "Acoustic Doppler Current Profiler " (ADCP) towedby a research boat and nearly synoptic hydrographic data were sampled in the SãoSebastião Channel (SSC) during six cruises between 2001 and 2006. This study alsouses ocean-surface wind fields for the South Brazil Bight (SBB) area derived fromthe QuikSCAT scatterometer. The method of objective analysis was applied to obtainthe horizontal and vertical distributions of temperature, salinity, density, velocity andwind. The estimated along-channel volume transport for the four vertical sections ar-ranged radially to the channel was almost continuous or discontinuous between theirvalues, probably mainly caused by the occurrence of anticyclonic or cyclonic gyresin the southern portion of the SSC and almost synopticity in data acquisition. Thecalculated volume transport in the channel ranged from 18,904 m3s−1on 13/11/2002heading north forced by southwesterly winds, to -1,959 m3s−1on 27/07/2006 headingsouth forced by northeasterly winds. Gyres were observed only in the southern portionof the channel. These gyres were cyclonic during northeasterly winds and anticyclonicduring southwesterly winds. The water renewal time of the SSC varies from 0.81 to7.81 days. On 27/07/2006, 10/10/2006 and 14/12/2006, bidirectional circulation intwo layers was observed, with surface currents heading SW, forced by northeasterlywinds, and deep currents heading N. On 14/12/2006 the whole bottom layer of theSSC was filled with South Atlantic Central Water (SACW), and its coastal upwellingwas observed at the southern continental coast of the channel, probably due to NE/SEwinds that blew between 8/12/2006 and 14/12/2006.