Estimation of annual heat flux balance at the sea surface from SST (NOAA-Satellite) and ships drift data off southeast Brazil

Abstract

ComputationJ developed by NOAAjNESS, USA, and sea surface current data based from ships drift info~ation obtained from Pilot Charts, published by the Diretoria de Hidrografia e Navegação (DHN, Brazilian NavyJ. The annual mean value of the heat flux balance at the sea surface off southeast Brazil for 19??, is estimated from data on the balance between the heat transported by the currents and that transported by eddy diffusion for each volume defined as 2° x 2° (Lat. x Long.J square with a constant depth equivalent to an oceanic mixed layer, 100 m thick. Results show several oceanic areas where there are net flows of heat from atmosphere towards the sea surface. In front of Rio de Janeiro the heat flow was downward and up to ?O ly day-l and is probably related to the upwelling phenomenon normally occurring in that area. Another coastal are a between Lat. 25°S to 28°S indicated an ábwnward flow up to 50 ly day-l; and for an area south of Lat. 2?oS, Long. 040 0 W -048°Wan ábwYU;Jard flow up to 200 ly day_l, where the transfer was probably due to the cold tUater of a nortward flux from the Falkland (MalvinasJ Current. Results also show several oceanic areas where net flows of heat (of about -100 ly day-lJ were toward the atmosphere. In the oceanic are as Lat. 19°5 -23°S and Lat. 24°S -30 0 S, the flows were probably due to the warm water of a southward flux of the Brazil Current. The resulting fluxes from the warm waters of the Brazil Current when compared with those from warm waters of the Gulf Stream and Kuroshio, indicate that the Gulf Stream carries about 3.3 times and the Kuroshio 1.? times more heat than the Brazil Current. These values agree with those of data available on the heat fluxes of the above mentioned Currents calculated by different methods (Budyko, 19?4J.