32nd Conference on Broadcast Meteorology/31st Conference on Radar Meteorology/Fifth Conference on Coastal Atmospheric and Oceanic Prediction and Processes

Thursday, 7 August 2003: 8:00 AM
Parameterization functions of the drag coefficient and ocean surface wind stress computation
Paul A. Hwang, NRL, Stennis Space Center, MS
Depending on the choice of reference wind speed, the quantitative and qualitative properties of the drag coefficient may vary. On the ocean surface, surface waves play an important role in controlling the air-sea exchange processes. The range of the dynamic influence of surface waves scales with wavelength. Drag coefficient computed with the reference wind speed at an elevation proportional to the wavelength (U_L/2) is fundamentally different from the drag coefficient computed with the wind speed at fixed 10 m elevation (U10). A comparison is carried out to quantify the resulting wind stress computation using several different parameterization functions of the drag coefficient. The results indicate that the drag coefficient referenced to U_L/2 yields more accurate wind stress from U_10 input compared to the drag coefficient referenced to U_10. This study highlights the importance of incorporating wave parameters (wavelength and phase velocity) in the parameterization of the drag coefficient.

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