A 16 Year Hindcast of Southeastern Brazilian Basin Using ROMS

Authors: Felipe Soares, Mauricio Fragoso, Gabriel Carvalho, Leonardo Marques da Cruz.
Affiliation: PROOCEANO.

To assess the climatology of mesoscale features of the Brazil Current (BC) near the Southeastern Brazilian Basin, a 16 year (1995 - 2010) hindcast has been developed. The model domain extends from 14ºS to 40ºS and from 22ºW to 55ºW, within a 250 (zonal) x 360 (meridional) x 20 (sigma) points curvilinear grid, and grid spacing ranging from 5 – 14 km, with the best resolutions near the Campos and Santos Basins. The initial and boundary conditions were obtained from the ECCO (Estimating the Circulation & Climate of the Ocean) Project, which is configured to better resolve the circulation in the tropics. The ECCO spatial grid resolution varies from 1º to 1/3º in the tropical region, with a temporal resolution of 10 days. The currents, temperature, salinity, and sea surface height fields are relative to the ECCO assimilative (Kalman Filter) 1993 to present simulation (http://ecco.jpl.nasa.gov/las/servlets/dataset). The 3D momentum fields were applied to the boundaries using a mixed radiation-nudging condition. Flather and Chapman conditions were used for depth integrated 2D momentum and free surface, respectively. Atmospheric forcing was applied using a bulk formulation, and the variables were obtained by NCEP-DOE Reanalysis 2, which presents ~1.8º grid resolution and 6 hour temporal resolution.

A preliminary analysis of an 8 year model solution was carried out from 1994 to 2002. The results have been analyzed, and basic analysis such as monthly means, suggests a strong intensification of the BC with increasing simulation time. Further investigation is being conducted in order to determine the causes of such intensification.