A numerical model on sea surface wind of typhoon and its hindcasting calibration

A numerical model on typhoon sea surface wind is developed and then tested. The model is devided into two parts. The first part is the derivation of the vertically averaged boundary layer dynamic equation and from the equation, a quasi-steady state of vertically averaged wind field of typhoon for a given pressure field is obtained; the second part is to convert vertically averaged wind to that at 10-m elevation. With observed Marex buoy data of three typhoon cases in the South China Sea, the model wind is calibrated.
The results show that, at buoy sites, the correlation coefficient is about 0.95 between the hindcast and the observed wind speeds. The error statistics show that the error of maximum value of wind speed is smaller than 2 m/s and the absolute mean relative error of wind speeds about 10% and wind direction 15° or so. With the hindcast wind as an input of the third generation wave model, the wave hindcast results are also well calibrated.