Constraints on drag and exchange coefficients at extreme wind speeds

Due to a lack of observations, the behaviour of air/sea interfacial flux coefficients at extreme wind speeds is not well known. In this study, simulations of a three-dimensional ocean model are forced by extreme tropical cyclone winds under various drag and exchange coefficient representations and flux parameterizations. The resulting sea surface temperature changes are compared with satellite observations of sea surface temperature changes caused by three tropical cyclones in the Australian region. The results support the contention, previously made on theoretical grounds, that the drag coefficient cannot monotonically increase with wind speed and must at least level out at extreme wind speeds. The results also suggest that mixing parameterizations need to be modified to give realistic surface cooling at extreme wind speeds.