| We present results obtained from two high densityXBT lines that run across the Atlantic Ocean, from Cape Townto New York City (AX08) and from Cape Town to Buenos Aires (AX18).A total of six and two realization were carried in linesAX08 and AX18, respectively, by January 2003.XBTs are deployed in high densitymode (every 30-40 km), except along AX08 north of 20N where theyare deployed in low density (every 100-150 km) mode.Additionally, profiling floats arealso deployed to obtain salinity profiles in some transects.The temperature sections reveal themajor ocean currents in the upper 800 m.The five AX08 transects are used to compute the water mass transportsof the major currents in the tropical Atlanticand to investigate their spatial and temporal variability.The two temperature sections across the SouthAtlantic (AX18) are used to estimate the upper ocean contributionto the Meridional Overturning Circulation by integrating the geostrophictransport across the subtropical gyre.In both lines, dynamic heights are computed using the XBTtemperature profiles with salinity derived from historical T-Srelationships. The dynamic heights estimated by combiningaltimeter data with climatological dynamic height fieldsare compared with the XBT-derived values. Theerror in XBT-derived dynamic height introduced by usinghistorical T-S relationships instead of synoptic salinity datafrom profiling floats are of the order of 1.5 cm in the tropicalAtlantic. The structure exhibited in the dynamic height and inthe altimeter-derived sea height fields do not reveal all thecomponents of the upper ocean current system, making thetemperature sections presented here critical for computingtransports and investigating the temporal and spatial variability ofthe upper ocean dynamics. Four and two transects are expected tobe carried out each year in lines AX08 and AX18, respectively.Data and preliminary results from these and other AOML-maintainedhigh density XBT lines can be found in:http://www.aoml.noaa.gov/phod/hdenxbt/ |
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