Mixed Layer Variability and Subduction in the SPURS Area

Abstract:

During the Salinity Processes in the Upper Ocean Regional Study (SPURS) I field campaign a high-density grid of Argo-type profiling floats were deployed surrounding the central mooring. The sixteen (16) floats were deployed in a 4 x 4 array with approximate 0.5 degree spacing and were programed to profile from 2000 meters to the surface every 5 days. The floats remained remarkably close to the heavily instrumented central mooring for the duration of the primary study period. Mixed layer salinity was at a maximum when the floats were deployed and slowly decreased through early spring. Multi year observations display spatial and temporal variability in both the mixed layer depth and salinity. Geostrophic velocities are calculated throughout the water column using dynamic height estimates. Combined with satellite wind stress fields, the calculated geostrophic velocities are utilized to investigate the variability of subduction dynamics and subduction rates in the region.