三个模式对2008年夏半年西南区降水预报效果的检验

Verification of Three Model Precipitation Forecast Performances in Southwest China in Summer Half Year,2008

利用AREM（-YWand SY）、T213L31、JAPAN三个模式对2008年夏半年（5~11月）西南地区（25°~34.5°N,97°~110.5°E）降水预报进行了统计检验,并对其中两次强降水过程的预报效果进行对比分析,以期了解各模式在西南地区的预报效果及特点,结果表明：（1）小雨-大雨量级JAPAN模式预报情况较好,暴雨量级T213L31、JAPAN、AREM均预报较好,大暴雨量级AREM-SY模式预报较好。（2）对西南地区的降水预报,T213L31预报偏强情况较多,AREM预报偏弱情况多,JAPAN预报相对适中。（3）在西南地区,当降水陡增（即实况降水量较前一天大一个量级以上,且雨量比前一天多5 mm以上）和其后强降水持续阶段,是各模式预报偏弱情况最可能发生的时期,同时也是各模式预报效果较差的时段。（4）三个模式在青藏高原东南缘地区均有降水空报现象,AREM模式的降水空报与其在此处存在低涡空报有关。（5）对于西南低涡这一尺度小、结构复杂的特殊天气系统,当前模式对其强度、位置和诱发的强降水预报效果仍有待提高。

In order to get the precipitation forecasting performance of three models,namely AREM（YW and SY）,T213L31 and JAPAN in Southwest China,the precipitation forecast from May to November in 2008 was statistically analyzed,and the forecasts for two heavy rain cases were verified detailedly.The results show that：（1） JAPAN forecasts well from light to heavy rain grades,T213L31,JAPAN,AREM all forecast well in rainstorm grade,and AREM-SY forecasts well in heavy rainstorm grade.（2） In southwest China,the rainfall forecasted by T213L31 is heavier than observation,AREM is lighter than observation and JAPAN forecasts relatively moderate.（3） In southwest China,in the period of rainfall increasing suddenly（comparing with the rainfall of last day,24 h observation precipitation in the very day is not only more than one grade but also over 5 mm larger） and the heavy rain continuing,models most likely forecast weaker than observation,and have poor precipitation forecasting skill.（4） All of the three models have false rain prediction on the southeast edge of the Qinghai-Xizang Plateau,and the false rain forecast of AREM perhaps relate to the false forecast of southwest vortex nearby.（5） For southwest vortex,because of its small scale and complex structure,it is still hard today to make accurate prediction for its intensity,location and the inducing heavy rain.