华中地区夏季区域性极端日降水事件变化特征及环流异常  

Regional mean daily precipitation extremes over Central China during boreal summer and its relation with the anomalous circulation patterns

作　　者：柯丹[1] 管兆勇[1] 

机构地区：[1]南京信息工程大学气象灾害省部共建教育部重点实验室,南京210044

出　　处：《气象学报》2014年第3期478-493,共16页Acta Meteorologica Sinica

基　　金：公益性行业(气象)科研专项(GYHY201406024);国家自然科学基金重点项目(41330425)

摘　　要：利用1961—2010年夏季(6—8月)华中区域239个中国国家级气象台站逐日降水观测资料及NCEP/NCAR再分析资料集,对华中地区夏季区域性极端日降水事件及环流异常进行了分析,结果表明:华中地区夏季区域性极端日降水量的99百分位阈值为23.585 mm/d,20世纪80年代中期以后的极端日降水事件明显偏多,且6月下旬至7月中旬为华中地区极端降水多发期。极端日降水事件由具有从低层到高层呈斜压结构的异常环流控制,其南侧的水汽通过孟加拉湾与中国南海地区的异常反气旋外围呈阶梯状输送至华中地区。位于青藏高原东北侧的波作用量通量向华中地区的辐合有利于华中地区上空波动扰动的产生和维持,同时极端日降水事件的发生亦与华中地区的大气净加热及华中周边大范围区域中的净冷却形成的加热场梯度有关。这些结果表明华中地区夏季区域性极端日降水事件有显著的年际和年代际变化,且极端事件的发生与华中地区气旋性环流异常、青藏高原东北侧地形强迫、以及华中地区与周边非绝热加热梯度异常关系密切。By using in situ precipitation records at the 239 stations in Central China （the Huazhong region）including Henan, Hubei and Hunan Province,and the NCEP/NCAR reanalysis data,the anomalous circulation patterns for the regional mean daily precipitation extreme （DPE）events over the Huazhong region in June,July and August of the boreal summer during the period from 1961 to 2010 were investigated.The results demonstrate that the threshold of the precipitation amount of the DPE events is 23.585 mm/d on the 99th percentile.The DPE events tend to occur more frequently from late June to mid-July,espe-cially after the mid-1980s.The circulation anomalies of DPE events show a baroclinic structure throughout the troposphere. The water vapor is transported from the periphery of an anomalous anticyclone in the Bay of Bengal and the South China Sea northward into Central China.The wave activity fluxes on the northeastern side of the Tibetan Plateau converge around the Huazhong region,which is favorable to generating and maintaining of the wave perturbation in this region.The DPE events are also related to the heat gradient caused by the local net heating of air over the region and the net cooling of air in the surround-ing areas.All of these suggest that the regional summer DPE events in Central China vary significantly on both interannual and interdecadal time scales.Also,the occurrences of the DPE events are closely associated with the anomalous cyclonic circula-tion,topographic forcing of the northeastern side of the Tibetan Plateau and the anomalous gradient of diabatic heating between Central China and the surrounding areas.

关 键 词：区域性极端降水 环流异常 波作用量通量 华中地区 北半球夏季 

分 类 号：P426.6[天文地球—大气科学及气象学]