Observations of Near-Surface Oceanic Velocity Strain-Rate Variability during and after Storm Events

Abstract

During August of 1977, a series of repeated profiles of the upper ocean were made at Ocean Station Papa (145°W, 50°N) with a velocity/temperature microstructure profiler. A strong correlation of wind-speed variations with velocity structures in the 20 m deep mixed layer was observed. Rates of dissipation of mechanical energy as high as 5 ? 10?2 ergs cm?2 s?1 were observed during wind speeds of 20 m s?1, and as low as instrumental noise (?10?6 ergs cm?3 s?1) during light winds. A persistent vertical separation of temperature and velocity variance maxima at high wavenumbers was found near the base of the mixed layer, in a region of strong vertical shear, suggesting that show-induced entrainment continued for several days after the storm events subsided.