Response time of mean square slope to wind forcing: An empirical investigation

We present an empirical study of the response time of surface wave mean square slope to local wind forcing using data collected over 11 years by 46 discus buoys moored at a wide variety of locations. The response time is defined as the time lag at which the time dependence of the waves exhibits the highest correlation with that of the local wind speed. The response time at each location is found to be fairly stable, with the time varying between 0.4 and 1.8 h depending on the location. Examination of long-term statistics reveals response time dependencies on wind speed magnitude, fetch, atmospheric stability, and wavelength. With the increasing reliance on satellite microwave remote sensing as a source of wind data, these results provide useful insights and bounds for their use.