2010年6月中旬浙闽赣地区暴雨特征和冰云热力效应的数值模拟分析

Modeling analysis of rainstorm characteristics and ice cloud thermal effect over Zhejiang,Fujian and Jiangxi in middle June 2010

以2010年6月19日发生在浙闽赣地区的一次强降水过程为例,利用中尺度WRF模式进行模拟,用模拟资料对该地区降水收支特征和冰云热力作用进行分析。依据局地水汽/热量变化项、水汽/热量辐合辐散项和云凝物辐合辐散项这3个因子可将降水分为8类,其中局地水汽变干和大气变暖、水汽辐合和热量辐散以及云凝物辐合时,降水强度(雨强)最强,而局地水汽变湿和大气变冷、水汽辐合和热量辐散以及云凝物辐合时,降水覆盖率最大。冰云热力效应包括辐射和潜热两部分。基准试验与敏感性试验对比分析表明冰云辐射减弱降水,而冰云潜热增强降水。热量收支对比分析发现冰云辐射造成辐射冷却的减弱在对流层中低层随高度增加,减弱大气不稳定和降水;而冰云潜热造成潜热增强在对流层中高层随高度减小,增强大气不稳定和降水。

The mesoscale WRF model was used to simulate a heavy rainfall process in Zhejiang,Fujian and Jiangxi Province on June 19,2010.The characteristics of precipitation budget and the thermal effect of ice clouds in this region were analyzed with the simulation data.According to the three factors of local water vapor/heat change,water vapor/heat convergence and cloud hydrometeor convergence,precipitation can be divided into eight categories.When local atmosphere dries and warms,water vapor convergence and heat divergence,and cloud hydrometeor convergence,precipitation intensity(rain intensity)is the strongest,while local water vapor becomes wet and atmosphere cools,water vapor convergence and heat divergence,and cloud condensate convergence,the rainfall coverage is the largest.The thermal effect of ice cloud includes radiation and latent heat.The comparison between control experiment and sensitivity experiments shows that the radiative effect of ice cloud decreases rainfall,while the latent heat of ice cloud enhances rainfall.The comparation analysis of heat budget shows that the decreasing of radiative cooling caused by ice cloud radiatiive effect increases with height in the middle and lower troposphere,which reduces atmospheric in stability and rainfall;while the increasing of latent heat caused by ice cloud latent heat decreases with height in the middle and upper troposphere,which enhances atmospheric instability and rainfall.