Seasonal variability and coastal upwelling near Cape Santa Marta (Brazil)

PAULA C. CAMPOS; OSMAR O. MOLLER JR.; ALBERTO R. PIOLA; ELBIO D. PALMA

JOURNAL OF GEOPHYSICAL RESEARCH

AMER GEOPHYSICAL UNION

Lugar: Washington; Año: 2012 vol. 118 p. 1 - 14

0148-0227

The Santa Marta Grande Cape (CSM) area, a relatively steep and narrow continentalshelf off southeast Brazil, is under the influence of the Brazil Current and intense seasonalvariations of the wind field that affect the composition of water masses and theircirculation. Hydrographic data, satellite-derived wind stress, and numerical simulations areused to characterize the seasonal and shorter period variability of the oceanographicconditions off CSM, in the area between 27
S and 30
S. The study is focused on theupwelling episodes and the dynamical mechanisms associated with these events. Field dataand numerical results indicate significant seasonal changes in the oceanographic structure,the water mass composition, and the dynamical balance. During fall and winter, whensouthwesterly winds prevail and the frequency of meteorological frontal systems increases,the region is characterized by waters of continental origin, the Plata Plume Water (PPW).During spring and summer, deeper waters reach the surface layer due to the action ofnortheasterly winds. Coastal upwelling events are revealed by surface temperature minimaobserved south of CSM. Synoptic data show that these events occur in pulses associatedwith changes in the wind direction. Analysis of the numerical results shows that thisparticular location of the upwelling band results from the synergy between shelf-breakupwelling and the regional shelf circulation induced by the northeasterly winds, both ofwhich are modulated by changes in the coastline orientation and shelf width.