Measuring Upper Ocean Variability from an Array of Surface Moorings in the Subtropical Convergence Zone

Abstract

Measurements of upper ocean variability were made in the subtropical convergence zone southwest of Bermuda from an array of five surface moorings set with spacings of 16 to 53 km. The intent was to observe oceanic fronts and to quantify the spatial gradients associated with them. Vector Measuring Current Meters (VMCMS) and Vector Averaging Current Meters (VACMS) were attached to the mooring lines beneath the surface buoys to measure velocities and temperatures. Modifications were made to the VMCMs in an attempt to improve data return. The performance and accuracy of these moored instruments are examined. Predeployment and postdeployment calibrations were carried out; and other sources of error, such as mooring motion, are considered. A number of oceanic fronts passed through the moored array during the experiment, and the horizontal gradients observed in the velocity and temperature fields were significantly larger than the uncertainties in measuring those gradients.