2009年我国汛期降水形势总结与三个常用模式预报效果检验

SUMMARY OF RAIN SITUATION OF CHINA IN FLOOD SEASON IN 2009 AND EVALUATION OF PREDICTION BY THREE MODELS

利用实况24小时降水、形势场资料及T213、T639、Japan模式降水、形势场的预报资料,对2009年汛期(5—9月,下同)中国降水时空分布进行分析,并对T213、T639、Japan三个常用模式对2009年汛期的天气形势、降水及其影响系统的预报做主客观检验,以期得出2009年汛期降水分布特点及三个模式的降水预报效果对比。结果表明:(1)2009年汛期华南地区降水量为全国之最,长江中下游和西南东部地区其次,东北和华北地区再次。(2)从TS评分看,Japan模式的小雨～大雨量级评分较高,T639模式暴雨～大暴雨量级评分较高;T213模式对华北地区暴雨、大暴雨量级降水预报评分高于Japan和T639模式。(3)从降水预报偏差看,T213模式对华北预报明显偏强,T639模式对华北预报强度较为适中,两模式对其他区域中等以下强度降水预报偏强,对强降水预报偏弱;T639对中等以下强度降水预报偏强程度明显小于T213,而对强降水除华南和东北区域外,预报偏弱程度明显大于T213;Japan模式预报偏差随降水量级增大而减小,对大雨以上各量级预报均明显偏弱,且偏弱程度明显大于T213、T639。(4)由代表性形势场预报检验结果可知,除T213对500 hPa高度场、850 hPa温度场预报效果好于其他两模式外,各模式预报效果相差不大。(5)三个模式对500 hPa副高总体预报偏东、偏北、偏强,但Japan预报效果明显好于T213、T639。(6)T639模式对台风和低涡的预报相对较好,T213较差。

Using 24 h rain observations and data of weather patterns as well as model predictions of rainfall from T213,T639 and Japan,the spatio-temporal distribution of rain in the flood season（May to September） in 2009 is summarized,and the rain,weather patterns and synoptic systems predicted by T213,T639 and Japan for this period are evaluated in order to obtain the distribution character of the rain in 2009 and to compare the prediction effect of the three models.The results are shown as follows.（1） The rain in the South China flood season in 2009 was the most of the whole China,followed in turn by that of the middle-and lower-reach of Yangtze River,the east of Southwest China,and Northeast China and North China.（2） In terms of TS,Japan was the highest for magnitudes from light to heavy rain,T639 was the highest for magnitudes from rainstorm to heavy storm,with the exception that for North China T213 was higher than either Japan or T639.（3） In terms of bias,T213 forecast heavier rainfall than the observation and T639 predicted modest rainfall in North China,and the two models forecast heavier amount for small and modest rain and lighter amount for heavy rain,while generally,T639 predicted lighter amount than T213 for small and modest rain and predicted heavier amount than T213 for heavy rain;the bias of rain prediction by Japan always decreased with the increase of rain magnitude,the predicted amount of Japan in rainstorm and heavy storm magnitudes was lighter than the observation,and was the lightest of the three models.（4） From the evaluation of the representative weather patterns,it is known that the prediction effect of the three models is equivalent to each other except that T213 predicts best for 500 hPa and 850 hPa temperature.（5） T213,T639 and Japan＇s predictions of the 500 hPa subtropical high are generally eastward and northward deviated from and stronger than the observation.Japan predicted the subtropical high significantly better than T213 and T639.（6） For the prediction of typhoons and low vortexes,T639 behaved the best,followed by Japan and then T213.