Analysis And Modeling Study Of Typhoon Sea Surface Wind Field In The Vicinity Of Taiwan

This study aims at modeling of typhoon sea surface wind field in the vicinity of Taiwan, where a mountain of 3000 m elevation and a narrow strait (the Taiwan Strait, 200 km width on average) were located. QuikSCAT remote sensing wind data from 1999 to 2005 as well as the"best size"data of the Northwest Pacific from 2001~2004 compiled by Joint Typhoon Warning Center (JTWC), were used to derive the characteristics of the typhoon wind field and the radius of maximum wind speed ( R max) of the Northwest Pacific. A typhoon wind field model was then developed for typhoon and storm surge simulation. Following were major results obtained:(1)Terrain had prominent effects on the formation of wind field features. Some interesting phenomena were observed, such as strong wind appearing in the Taiwan Strait early, formation of leeward trough and"corner flow"to the flanks of Center Mountain Range (CMR) and downstream the tips of CMR respectively. Effects of terrain were mainly related to position of typhoon center, typhoon strength and size, but less to typhoon track.(2)In the Northwest Pacific, 73% of R max was between 28 km and 56km, and the average of R max was 47km. When the maximum wind speed ( V max) got stronger, R max tended to be smaller and the distribution of R max became more concentrated; R max fitted V max better after the low probability data were excluded.(3)A typhoon wind field model was developed by combining two correction modules with an ideal wind model. The first module was for wind direction correction, which accounted for the"splitting influence"and"blocking influence"of terrain on wind direction. The second module was for wind speed correction, which took accounts for the enhancement of wind strength due to the specific terrain of the study region. Using this model, typhoon wind field was simulated, leading to a wind pattern generally consistent with that observed by QuikSCAT. The simulated wind was then applied to a storm surge model. Mean absolute error( MAE )of all the cases included in the modeling was 19.1 cm. The MAE was <=20 cm for 79% of the experimental cases, and 68% of maximum storm surge error( MSE )was between -20 cm to 20 cm. It was thus demonstrated that the typhoon wind field model proposed in this study was generally successful in the sense of reproducing the real typhoon wind pattern in...