摘要:
台风Maggie(9903)的移动路径属于历史上罕见的疑难路径之一,在1999年6月6日0时(UTC,下同),台风位于22.3°N,119.8°E附近,它向西北方向移动,于6月6日12时抵达广东汕尾附近海面,然后沿海岸线折向西南行,于6月7日下午到达阳江附近海面,经历一次360°的打转后再折向北行在阳江登陆,澳门地球物理暨气象局以MM5为基础的台风数值预报试验系统在6月6日0时相当准确地报出Maggie的未来48h移动路径和降水,敏感性试验说明,华南大陆的海岸线走向和地形对Maggie的移动路径无明显的影响,它之所以沿海岸线折向西南行应是其环境场改变的结果,把华南陆地变为海洋后,Maggie在向西南移动过程中继续发展,这说明,当台风接近陆地或登陆后,陆面摩擦和下垫面水气供应的减少是引起台风减弱的主要因子。
Abstract:
The movement of Typhoon Maggie(9903) in June 1999 is one of the rare cases ever seen in the history.At 00U on June 6 Maggie was located at about 70 km to the southwest of Taiwan.When it arrived at the coastal region of Shanwei City(22.8°N,116.5°E),it turned suddenly to move southwestward along the southern China coastal line.On June 7 Maggie finally turned to move northward,making landfall to the north of Shangchuan Island.The experimental numerical prediction system on typhoon movement that was designed based on MM5 is proved quite successful for the 48 h prediction of Maggie's movement and rainfall.The mean prediction error of typhoon track is 81 km for 0-24 h and 74 km for 24-48 h.The location of typhoon center in the initial field of the model is approximately 100 km away from the actual observations.In order to modify the location of typhoon center,a bogus typhoon was introduced into the model and the prediction of typhoon track was improved in 0-24 h time interval.But the prediction error was enlarged in 24-36 h.We also performed a sensitivity experiment of changing the land of southern China into the ocean.It is found that the orientation of South China coastal line and the topography have no obvious effect on the movement of Typhoon Maggie.
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