区域中尺度模式对西南地区一次强降水过程的预报分析

Analyses on a Heavy Rainfall Process Prediction of Regional Numerical Models

为了认识区域数值模式对西南地区降水预报能力,探索降水预报误差原因,本文应用MICAP资料,NCEP再分析资料,FY-2E辐射亮温资料,自动站资料,西南涡加密观测资料等,针对2012年7月2～5日西南地区一次强降水过程,分析了西南区域中心运行的WRF模式和GRAPES中尺度模式的预报能力,得到：（1）两模式不同程度反映了本次强降水过程.相对而言,WRF模式的预报略好于GRAPES,得益于WRF模式对对流层中低层温度、水汽、流场等演变的较好反映.（2）两模式预报对流层中低层温度偏差总体呈现正偏差,GRAPES模式呈现较大的温度偏差,正偏差特征更显著.两模式不同程度出现空报降水,特别是在高原东南坡.GRAPES模式空报雨区特征更明显.（3）两模式预报近地层湿度较实况大,都预报高原南坡,特别是高原东南坡风场辐合、水汽场辐合偏强,可能是造成虚假降水的主要原因.（4）较实况,WRF模式预报对流层高层的高压和对流层中低层的低压系统偏强,GRAPES模式预报西南低空急流偏强（可能是引起温度正偏差的原因）,两个模式预报的对流层正涡度较深厚,辐合上升运动强,这些可能是造成降水预报偏差的原因.

Using MICAPS data , NCEP 1°×°re -analysis data, FY- 2E infrared temperature data , south -west vortex observation data and so on, prediction capabilities of WRY model and GRAPES model run at Southwest Region Meteorology Center have been examined aimed at the model predictions of an heavy rainfall process over southwest area during 2nd to 5th July, 2012. The re- sults show that ： 1 ） The two models reflect the precipitation process on some degree. Comparatively, the prediction of WRF model is better than that of GRAPES model, which profit form WRF model provided better the prediction of temperature, water vapor, stream fields on lower- middle troposphere. 2） Temperature prediction errors of the two modes in lower- middle troposphere are collectivity positive differences. The error of GRAPES model is bigger than that of WRF model. The two models predict false precipitation on some degree, especially in the southeast of Qinghai - Tibet Plateau . The prediction characteristics of GRAPES model is more obvious. 3） The humidity field predictions of the two models are bigger than the real near ground, at the same time, stream fields convergence and water vapor fields convergence prediction of the two model are stronger than that of the real ,which are likely to the main reasons of false precipitation prediction. 4）Compared with the real, the predictions of the high pressure on upper troposphere and low pressure system on lower- middle troposphere of WRF model are stronger, the southwest jets （maybe cause positive temperature difference） prediction of GRAPES model is stronger on lower troposphere ,as well as the positive vortexes are deeper, the convergence and ascent movements are stronger for the two models ,which are likely to the reasons of precipitation prediction errors.