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Since 2001,57 months of CARIOCA measurements spread over all seasons have been acquired in the Southern Ocean (in the three ocean basins Atlantic Pacific and Indian) between 38°S and 56°S.CARIOCA drifters measure each hour,at 2 meters depth,ocean CO2 partial pressure,pCO2,sea surface temperature,SST,salinity,SSS,fluorescence,and in the atmosphere surface wind speed,atmospheric pressure and air temperature.Continuous time series of CARIOCA measurements made during all seasons in this latitude range indicate that pCO2 in sea water is undersaturated with respect to the atmospheric value.In this poster,we concentrate on measurements acquired by a CARIOCA buoy deployed in the Southern Atlantic Ocean in January 2006 that records 11 months of data (it is still functioning),and that crossed the Atlantic Ocean from 57S 63W to 48S 23E.Over this trajectory,pCO2 range between 335 and 375 matm.The largest DpCO2 (in absolute value) are observed between 50°W and 30°W,and are of similar magnitude as Takahashi (2002) climatology.Air-sea CO2 fluxes in 2006 are in the lower bound of seasonal fluxes derived from other CARIOCA drifting in the Indian and Pacific Oceans.One reson is that 2006 CARIOCA remains south of the subantarctic front,SAF,in the polar zone,whereas the others buoys explored the subantarctic zone.Actually 2006 CARIOCA records low sea surface salinity (SSS < 34) and low sea surface temperature (SST<8°C).Climatological fronts (Orsi et al.,1995; Belkin and Gordon 1996) were found too approximative to precisely locate CARIOCA with respect to SAF.Thence we detect SAF from Microwave Optimally Interpolated (OI) Sea Surface Temperature (SST) maps using the methodology proposed by (Moore et al.,1999) and (Burls and Reason,2006).This method is shown to well locate the front with respect to SSS recorded by both CARIOCA drifter and ARGO floats in the middle of the Atlantic Ocean and will be used to determine the surface of the polar zone and to properly integrate flux estimates.From 12 to 18 Sept.18,2006,close to 49S,9W-5W,CARIOCA recorded very large SSS (between 34.5 and 34.9) and very low SST (between 1.2°C and 2°C).This SST anomaly also appears as a cold anomaly during a few days on satellite SST images.The anomaly on pCO2 is small but dissolved inorganic carbon (DIC) derived from CARIOCA pCO2 and SSS using the alkalinity-SSS relationship of Lee et al.(2006) indicates an anomaly of 60mmol kg -1.