The Vertical Mean Wind Profile Over the Ocean for Light to Moderate Winds

Abstract

Analysis of 299 wind profile observations collected at the Massachusetts Institute of Technology oceano-graphic research platform provides a detailed picture of the behavior of wind profile parameters. A plot of roughness length vs velocity suggests the existence of classical hydrodynamic phenomena such as Jeffreys? minimum wind speed and the Kelvin-Helmholtz instability. The friction velocity appears to be, in general, a linear function of the wind velocity, except in regions where discontinuities exist. It is suggested that the air flow regime over the ocean in the wind range of 2-10 m sec?1 (measured at a height of 10 m) is best described as a region of constant drag coefficient (CD = 1.6 ? 10?3) modified by the superposition of almost singular departures at a number of discrete wind speeds, apparently caused by the onset of distinct instabilities at the water's surface.