In this project, the investigators will carry out a high-quality hydrographic section along with Acoustic Doppler Current Profiling across the Atlantic Ocean along 8 deg N. This section will complement an intensive deep float deployment to be carried out by other investigators. Geostrophic shear from the CTD data, together with the float trajectories, will be used to extrapolate the velocity field away from the float-derived level of known motion to obtain the top-to-bottom, basin-wide absolute velocity field. Measurements of salinity, oxygen, and nutrient distributions will allow interpretation of the velocity field in terms of source water masses. Acoustic Doppler Current Profiles of the upper few hundred meters, coupled with GPS navigation, will provide additional information on the absolute velocity field, and will also be used to distinguish between geostrophic and ageostrophic (Ekman) shear on large space-scales in the upper ocean. Scientific issues to be addressed by the study include the fluxes of heat and freshwater and the transport and dynamics of deep water masses.
