Wind Velocity Predictions over the Penghu Islands of Taiwan during Tropical Cyclones

Abstract:

The purposes of this study were to forecast the hourly wind velocity over the Penghu Islands during tropical cyclones, and to determine the effects of the Central Mountain Range (CMR) terrain of Taiwan over the Penghu Islands based on typhoon tracks. On average, a destructive typhoon hits the Penghu Islands every 15-20 years. As a typhoon approaches Penghu Islands, its track and intensity are influenced by the CMR topography. Therefore, CMR complicates the wind forecast of the Penghu Islands. Six main typhoon tracks (Classes I-VI) are classified based on typhoon directions, as follows: (I) the direction of direct westward movement across CMR of Taiwan, (II) the direction of northward movement traveling through Taiwan Strait, (III) the direction of northward movement along the western coast of Taiwan, (IV) the direction of westward movement traveling through Luzon Strait, (V) the direction of westward movement traveling through the southern East China Sea (near Northern Taiwan), and (VI) the irregular track direction. The adaptive network-based fuzzy inference system (ANFIS) and multilayer perceptron neural network (MLPNN) were used as the forecasting technique to predict the wind velocity. We analyzed 49 typhoons from 2000 to 2012. Results showed that the ANFIS models provided high-reliability predictions for wind velocity, and the ANFIS achieved more favorable performance than did the MLPNN. In addition, we provide a detailed discussion on the interaction of the CMR with the Penghu Islands based on various track directions.