In situ measurements of ocean-atmosphere heat fluxes in high latitudes of the South Atlantic and Southern Ocean

Ocean-atmosphere coupling measurements have been taken for over a decade onboard Brazilian research vessels in high latitudes (> 30oS) of the South Atlantic and recently in the Drake Passage in the Southern Ocean. Measurements are aimed to characterize the Marine Atmospheric Boundary Layer (MABL) and to estimate the sensible and latent heat fluxes between the ocean and the atmosphere. The importance of the local sea surface temperature and the large scale atmospheric pressure fields on the MABL modulation in the study area has been described. Our main results demonstrate that in the study region the cyclogenesis and atmospheric cold fronts passage are key to modulate the characteristics of the MABL and the heat fluxes at the atmospheric synoptic scale. The impact of oceanic mesoscale variability on the MABL and heat fluxes modulation is prominent during the life cycle of eddies present at the eastern and western boundaries of the South Atlantic. Direct measurements made using the Eddy Covariance technique from measurements taken from a micrometeorological tower installed in our research ships show that there is a consistent bias of about 50 W.m-2 between direct and parameterized latent heat fluxes with high potential of jeopardizing the weather forecast in Southern South America.