Adaptive Modeling for Typhoon Wave Predictions around Taiwan

In this paper, we apply a quadtree-adaptive scheme for hindcasting wave spectra during Typhoon Soulik. In the simulation, the quadtree grid system can be adapted to the vicinity of the typhoon and some prescribed regions, where require higher resolutions. In other words, the quadtree grid system can move with the typhoon and then reduce the number of grids for computation. In our simulations we consider a square computational domain of 3,200*3,200 square kilometers with its center at latitude 26.5°N and longitude 126.5° W, and use the combined wind fields of the NOAA operational wave model and the model of Taiwan's Central Weather Bureau. The required computing time for the adaptive scheme is about 10 times shorter compared with that of the traditional model. In an adaptive simulation with the highest spatial resolution of 25 kilometers and temporal resolution of 1 hour, the required computing time is only 0.67 hours for the 7-days typhoon event. At the same time, the difference between the predicted significant wave heights and the buoy measurements is accredited. These results indicate that the proposed adaptive scheme can significantly save the time required for a specific simulation and is very convenient for an operational forecasting.