0806号台风“风神”过程分析及预报精度评估

Analysis and Forecast Evaluation on Typhoon "Fengshen"(0806)

本文利用NECP一天4次的1°×1°和2.5°×2.5°经纬网格再分析资料以及一周1次的NOAA海温资料,对0806号台风"风神"的移动路径、强度进行分析。结果表明:"风神"的移动路径与副高位置的演变有关,"风神"发展过程中强度变化不仅与其非对称结构及环境流场的影响相关,而且后期南部低层冷空气的侵入对"风神"强度的减弱有一定影响。2008年6月南海海温低于常年是近海台风活动减少的可能原因,西南季风指数对南海及附近海域的台风活动有一定指示意义。对实时的综合预报和数值预报结果检验表明:各业务预报中心对路径预报意见相对一致,路径均偏东,且误差较大,数值预报和客观分析方法效果相当。强度预报中北京综合预报和上海台风模式预报效果较好。

Based on the data of 1°×1°NCEP reanalysis,2.5°×2.5° NECP reanalysis,and 1°×1° NOAA SST,the moving track and intensity of Typhoon Fengshen(0806)are analyzed.The results indicate that the moving track of Fengshen had a close relation to subtropical high.The intensity change was not only related to the asymmetric structure and environmental flow field,but also to the cold air in the low levels from south which would help decrease the intensity of Fengshen.The reduction of typhoon intensity may result from the unusually lower sea surface temperature of the South China Sea,and the index of southwest monsoon can provide more valuable information for the typhoons over the South China Sea and the neighboring sea area.Examinations on the real-time subjective and objective forecasts show that they nearly had the same track forecast result for Fengshen.The tracks were biasing to the east,and they had larger errors than usual.The numerical model performances were quite similar to that of the objective analysis methods.And for the intensity forecast,The Beijing subjective forecast and the Shanghai Typhoon Model performed much better than other methods.