10. Coupled Nature of Hurricane Wind and Wave Properties for Ocean Remote Sensing of Hurricane Wind Speed

Wind measurement using microwave radar suffers decreased or loss of sensitivity of the return signal in high winds. The 2D wavenumber spectra collected by airborne scanning radar altimeter in hurricane hunter missions are used to investigate the fetch- and duration-limited nature of wave growth inside hurricanes. Despite the much more complex wind forcing conditions, the dimensionless growth curves obtained with the wind wave triplets (reference wind velocity, significant wave height and dominant wave period) inside hurricanes except near the eye region are comparable to the reference similarity counterparts constructed with the wind wave triplets collected in field experiments conducted under ideal quasi-steady fetch-limited conditions. Making use of this property, the hurricane wind speed is retrievable from the dominant wave parameter (significant wave height or dominant wave period) using the fetch- or duration-limited wave growth functions. An algorithm based on such consideration is developed and applied to two hurricanes of different strengths (category 2 and 4). The retrieved wind speeds are in good agreement with the reference wind speeds from hurricane hunter measurements, and there is no indication of saturation problem in the wind retrieval using the dominant wave parameters.