[1] This paper presents a description of marine atmospheric boundary layer (MABL) and oceanic boundary layer (OBL) interactions at the Brazil-Malvinas Confluence. Although this region is known as one of the most energetic zones of the World Ocean, very few studies have addressed the mechanisms of OA interaction there. Based upon novel, direct in situ simultaneous OA observations, our results show that the OBL-MABL exchanges are closely correlated with the sea surface temperature (SST) field. The heat fluxes range from 110 W.m À2 over warm waters down to 18 W.m À2 over cold waters. Higher heat fluxes and air-sea temperature differences are associated with stronger near-surface winds. This suggests that the MABL is modulated at the synoptic temporal and spatial scale by the strong surface thermal gradients between the (warm) Brazil and the (cold) Malvinas (Falklands) currents. Citation:

[1] A three-dimensional regional model is used to investigate the role of different terms of the salinity budget in the western Pacific during TOGA COARE. The model is a version of the ocean general circulation model (OGCM) developed at the Laboratoire d'Océanographie Dynamique et de Climatologie (LODYC) in Paris and includes open lateral boundaries and a 1.5-level-order turbulence closure scheme. The surface atmospheric forcing used, including water flux, comes from a combination of European Center for Medium-Range Weather Forecasts model output and estimates from bulk parameterization. The data set collected during the Intensive Observation Period enables the initialization, taking into account the lateral boundary conditions, and validating the model outputs. Different atmospheric weather conditions were experienced during the simulation of the variability of the mixed layer. During 25 days, air-sea fluxes were downward, that is precipitation exceeds evaporation, and increasing with time. In periods of weak winds (December 2-12), strong solar radiation, and shoaling of the oceanic mixed layer, the entrainment is negative and salt is removed from the oceanic mixed layer. Mixed layer currents are low and slightly divergent from the equator toward the south with a mean eastward component. Due to the zonal advection, there is a freshening tendency in the north of the domain. In periods of strong winds (December 21-27) and reduced solar radiation, the oceanic mixed layer is deepening and entrainment is positive and contributes to the salinity increase. The salinity storage term is quite inhomogeneous during the two periods as a consequence of the patchy pattern of advection. Moreover, most of its temporal and spatial variability is strongly correlated with the temporal and spatial variability of the advection term. Currents are largely converging toward the equator and create a band of saltier water in the surface layer.INDEX TERMS: 1610 Global Change: Atmosphere (0315, 0325); 1803 Hydrology: Anthropogenic effects; 1615 Global Change: Biogeochemical processes (4805); KEYWORDS: oceanic salinity budget, TOGA COARE, air-sea interaction, mesoscale modeling Citation: Dourado, M., and G. Caniaux, Surface salinity budget in oceanic simulation using data from TOGA COARE,

Time evolution of atmospheric and oceanic boundary layers are described for an upwelling region in the Atlantic Ocean located in Cabo Frio, Brazil (23°00'S, 42°08'W). The observations were obtained during a field campaign carried out by the "Instituto de Estudos do Mar Almirante Paulo Moreira", on board of the oceanographic ship Antares of the Brazilian Navy, between July 7 and 10 of 1992. The analysis shown here was based on 19 simultaneous vertical soundings of atmosphere and ocean, carried out consecutively every 4 hours. The period of observation was characterized by a passage of a cold front that penetrated in Cabo Frio on July 6. During the cold front passage the vertical extension of atmospheric (and oceanic) mixed layer varied from 200 m (and 13 m) to 1000 m (and 59 m). These changes occurred in the first day of observation and were followed by an increase of 1.2°C in the oceanic mixed layer temperature and by a decrease of 6 K and 6 g/kg in the virtual potential temperature and specific humidity of the atmospheric mixed layer. The short time scale variations in the ocean can be explained in terms of the substitution of cold upwelling water by warm downwelling water regime, as the surface winds shift from pre-frontal NE to post-frontal SSW during the cold front passage in Cabo Frio. The large vertical extent of the atmospheric mixed layer can be explained in terms of an intensification of the thermal mixing induced by the warming of the oceanic upper layers combined with the cooling of the lower atmospheric layers during the cold front passage. An intensification of the mechanical mixing, observed during the cold front passage, may also be contributing to the observed variations in the vertical extent of both layers.

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