AbstractThe Objective Analysis, which is widely implemented in routine weather forecsting, is utilized in present study to predict typhoon waves around Taiwan. In order to establish the statistical model, large amount information of historical typhoon waves, which were obtained by observations and numerical model simulations, have been adopted.
Due to the following facts that the typhoon wind fields features the nature of highly temporal and spatial variation, and that the typhoon wave filed is largely influenced by the evolution of typhoon swells, the Hybrid Wave Model proposed by Wen(1999) is utilized in present study to simulate the typhoon waves. Concerning to the input of the wave model, the predicted wind field is calculated using Lee(1993)’s formula, which were derived based on Ekman theory. The predicted wind direction and wind speed at the elevation of 10 m could thus be estimated from the forecasting barometric field, which is provided by Central Weather Bureau every twelve hours.
As the barometric data issued with time interval of 12 hours, details of the fast moving typhoon might not be conserved. For the sake to obtain accurate interpolation of barometric for single hour estimation, an new interpolation method is proposed in present study. The method entitled as Shift Linear Interpolation, is proved to be capable of eliminating the unreasonable results of using tradictional linear interpolation, such as the appearance of two typhoon eyes. Finally, the statistical model established using objective analysis is validated by observed typhoon wave. The results demonstrate the effective of present model.
The present typhoon wave forecasting model is easy to be implemented. It is useful for engineering applications when there is no numerical wind field available and providing typhoon wave forecast for a specific site in the offshore or coastal regions is necessary.
|Date of Award||2003|
|Supervisor||Zsu-Hsin Chuang (Supervisor)|