Monday, 24 March 2003
Impact of high frequency winds on the determination of mean and seasonal stresses over the ocean
Studies of the axial atmospheric angular momentum and torque balance have revealed large uncertainties in the estimated seasonal variability of zonal wind stress over the ocean. Because of the nonlinear dependence of stress on wind speed, variability in surface winds at weekly and shorter periods can have an important effect in determining the mean and seasonal cycle in ocean surface stresses. Using available satellite-derived and operational wind products, we show that these high frequency wind effects are indeed important and most pronounced in regions of strong synoptic activity like the Southern Ocean. Differences in various wind products are used to assess the possible role of errors in high frequency ocean winds in causing uncertainties in the mean and seasonal ocean stresses. We attempt to determine what frequency ranges are most important and how well we must know those scales to be able to improve knowledge of the mean and seasonal stresses. Implications for ocean modeling and studies of atmospheric momentum and torque balance are discussed.
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