GRAPES_TCM模式对影响浙江省热带气旋风力的预报评估

基于2006—2011年热带气旋影响时浙江省气象站实测风力和上海台风研究所GRAPES_TCM模式输出资料分析得出:模式地形高度与实际差异越大则直接输出风速平均误差越大,通过对浙江沿海模式地形高度误差绝对值在10 m以内的站点进行风力预报评估,结果发现:12~72 h模式直接输出风速存在一定的系统性误差。模式对浙江沿海站点风力预报的TS评分随风力等级的提高而降低,主要缘于空报率的增大。BS评分则表明,模式对越强的风力越有过度预报的倾向。模式20时预报的TS评分一般好于08时,主要得益于漏报率的降低。经MOS释用后可以在一定程度上提高站点风力预报与实况的正相关和预报稳定性,同时提高不同等级风力预报的TS评分;12、24 h模式站点,6级以上风力预报能力与主观预报相当。

Verification of wind forecasts in tropical cyclones in Zhejiang province based on GRAPES_TCM model

Based on wind speed of tropical cyclones from automatic weather stations in Zhejiang and GRAPES_TCM model outputs of U, V at 10 m from Shanghai Typhoon Institute during 2006-2011, verification has been carried out on different speed criteria in coastal areas of Zhejiang province. Result shows that the more the terrain simulation deviations are, the greater the mean errors of GRAPES model direct output velocity are. Wind speed verification at the stations with absolute model terrain deviations less than 10 m indicates that there exist systematic errors in the model output velocities for the leading hours of 12-72 h. Threat scores tend to descend with speed criteria ascending, owing to increasing false alarming ratio. Bias scores imply that the model tends to overforecast the winds. Analysis indicates that the model outputs issued at 08 PM perform better than those at 08 AM because of the declining missing event ratio. MOS can improve correlation coefficients between forecast and practical speeds, as well as output stability and Threat scores, moreover, to some extent, it can also help improve the model Threat scores under different wind scales, it is proved to be able to forecast for leading hours of 12 and 24 h and for wind force over 6 scale as good as the subjective one.