Mooring motion influences on current measurements

An important observational problem related to improving coupled ocean-atmosphere models is the determination of the vertical distribution of horizontal currents generated in the upper mixed layer of the ocean by the passage of a storm. Mixed layer shears might be as large as 0.04 sec-1. Because rectification of near-surface current measurements by mooring line motions reduces the accuracy of near-surface circulation studies, to what extent do moored current measurements represent the near-surface horizontal velocity field? Results from several intercomparison tests indicate that mooring-related rectification of AMF vector-averaging current meter (VACM) measurements made near the surface beneath a surface-following float moored in deep-water was small, approximately a few cm sec-1, or 10-15 percent of the near-surface current generated by a storm.