Seasonal Hydrodynamics and Transport Timescale of a Coastal Island

Abstract

Santa Catarina Island, situated at the city of Florianopo-lis has over 450000 people and is the 2nd most populous island in Brazil, with 88km of sandy beaches. Located between the island and the continent are the North and South Bays, with an average depth of 5m. The Southeastern Brazilian coast is constantly affected by the passage of frontal systems remotely generated on the Argentine continental shelf. These remote signals can induce shelf waves with periods of several days, playing a key role in mean sea level (MSL) variations (Castro and Lee, 1995). Remote winds blowing parallel to the Southeastern Brazilian coast from the south quad-rant tend to increase the mean sea level, while winds from the north quadrant induce a lowering of the MSL. Consequently, these sea level fluctuations may generate coastal currents that are dissociated from the astronom-ical tide, with heights in the same order of magnitude as the astronomical components (Melo et al., 2016; Dottori and Castro, 2018). To provide useful information, this paper aims to de-scribe the coastal hydrodynamics and assess the transport timescales of Santa Catarina Island, including the North and South Bays. To represent seasonality, two scenarios comprising 3 months each - winter and sum-mer - were defined, with different meteorological and hydrological conditions.