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

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  • 1 Scripps Institution of Oceanography, University of California, La Jolla 92093
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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.

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.

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