全球模式对华北区域性强降水中期预报能力检验

The performance verification of several numerical models in middle range forecasting of regional heavy rainfall in North China

选取2010—2016年夏季华北70个典型强降水个例,根据环流形势场,将其分为低涡型、西来槽型和切变线型。然后,利用降水空间检验法(MODE方法),通过对比质心距离、轴角以及纵横比等要素,讨论了几种常规业务模式对华北地区夏季强降水的中期预报能力。结果表明:ECMWF模式和T639模式对低涡型强降水预报能力较差;当实况强降水落区范围较大时,ECMWF模式和T639模式中期预报的雨带为狭长型并呈东北—西南向,预报与实况较为一致,但两种模式预报的降水落区均较实况偏西、偏南;这两种模式对较小面积降水,其预报的降水范围较实况偏大,而对较大面积降水,预报较实况明显偏小。

Seventy(70)typical heavy rainfall cases in North China during the summers from2010to2016were selected and divided intothree categories,i.e.the vortex type,the west trough type and shear line type according to the atmospheric circulation.Then we verified themiddle range forecasting abilities of several operational models to the regional heavy rainfall in summer in North China by using the MODEmethod and the contrast of the difference of centroidal distance,axis angel and aspect ratios,etc.The results show that ECMWF and T639models cannot well forecast the vortex-typed regional heavy rainfall.When the area of heavy rainfall is large,the rain belt predicted by ECMWFand T639models show a long-narrow shape in the northeast to southwest direction,which is consistent with observations.However,thelocation of heavy rainfall predicted by ECMWF and T639models deviate to the south and to the west with respect to observations.The heavyrainfall area predicted by ECMWF and T639models is bigger than observations for small area of rainfall cases,but far smaller for widespreadrainfall cases.