江南地面热通量对江淮气旋暴雨影响的模拟研究  

THE SIMULATION STUAY OF THE EFFECTS OF UPPER STREAM SURFACE THERMAL FLUXES ON CHANG JIANG HUAIHE RIVER BASIN CYCLONE ACCOMPANIED WITH HEAVY RAIN

作　　者：翟国庆[1] 高坤[1] 

机构地区：[1]杭州大学地理系

出　　处：《气象学报》1997年第1期55-65,共11页Acta Meteorologica Sinica

基　　金：国家自然科学基金;浙江省自然科学基金

摘　　要：通过对一次江淮气旋暴雨个例的数值模拟，研究地面热通量与大尺度流型结合作用对气旋降水系统的影响。过程前期存在南北两大片地面热通量正值区，北片位于气旋所在处及其前方，南片位于上游低空急流处。模拟比较两片地面热通量的作用发现，前期南片地面热通量，特别是强潜热通量，通过与其上空低空急流的共同作用，对后期下游江淮气旋降水系统的加强起着更为重要的作用。对其机制的初步探讨表明：由地面通量进入低层大气的水汽，通过西南气流向长江中下游输送，改变下游大气的温湿结构，并通过积云对流和层状云雨潜热释放等非绝热过程。By conducting some numerical simulations for a cyclone case in Changjiang Huaihe River basin, the combination effects of surface themal fluxes and large scale flow patterns on cyclonic precipitation system are investigated. The surface thermal fluxes distribution in the stage preceding development of the cyclone shows that there are two large areas of strong positive surface heat and moisture fluxes, one north area to the northeast of the cyclone, another south area underneath the upper stream low level jet. Comparing the roles of surface thermal fluxes in the two areas by sensitivity simulations withholding fluxes in the two areas, the surface thermal fluxes in south area, especially the strong moisture fluxes occurring before development of the cyclone, make more substantial contributions to the later intensification of the cyclonic precipitation system. It causes cyclone deepening 4 hPa more and about 70 percent increment of the central intensity of 24 hour accumulated precipitation. The evaporated moisture from surface underneath the low level jet in the early stage is transferred downstream into the middle and lower reaches of Changjiang river with southwest flow, and the accumulation of moisture there lead to moistenning of lower layer, especially in the top of boundary layer, which causes slightly stabilization of low level air and strong destabilization above boundary layer. This characteristics of stability is favorable for the accumulation of instability energy and the intensification of low level jet near boundary layer top by reducing the vertical mixing of momentum, which also intensify the transfer of moisture. The downstream accumulation of moisture near boundary layer top also causes frontogenesis, and enhances stratiform cloud and stratiform precipitation, whose releasing of latent heat is advantageous to the deepening of cyclone and the enhancing of lower level convergence intensifing the front secondary vertical circulation by the rapid release of the instability energy. By which the peak

关 键 词：边界层 地面热通量 暴雨 江淮地区 气旋 

分 类 号：P458.121.1[天文地球—大气科学及气象学]