1998年淮河试验加密观测期间大气可降水的估算及其特征分析

摘要

GMS-5 satellite data at channels of infrared split windows and water vapor are analyzed to retrieve the precipitable water (PW) distributions under cloud-free conditions. Radiosonde data and surface station data are applied to estimate the PW distributions under cloudy conditions. These two methods are then merged to obtain the PW distributions under ali-weather conditions during the Huaihe River Basin Energy and Water Cycle Experiment (HUBEX). The results of the all-weather PW distributions from these methods demonstrate that this new merging technique may be applied to derive large-scale or global maps of PW. It is revealed that the atmospheric water vapor over the Yangtze-Huaihe River Basins came mainly from the southwest during the 1998 prevailing period of Meiyu. Sufficient atmospheric PW is a necessary condition for ground rainfall. Under certain dynamic conditions, it can be partially transformed into surface precipitation. Several types of rain are displayed and their PW conditions and characteristics,as well as atmospheric dynamic conditions, are analyzed. It is demonstrated that surface precipitation centers usually appear not at the high PW centers but on their downwind sides.%利用GMS-5卫星红外分裂窗通道和水汽通道资料反演晴空大气的可降水分布,同时利用探空站资料和地面站资料估算云天大气的可降水分布.将这两种方法进行融合,得到淮河流域能量与水分循环试验期间全天候的大气可降水分布.结果表明,这种新的融合技术可应用于确定大尺度或全球尺度的大气可降水分布图像.揭示了江淮流域1998年梅雨盛行期大气中的水汽主要来源于西南方向.充足的大气可降水是产生地面降水的必要条件,在某些动力条件的影响下,空中的大气可降水将部分地被转化为地面降水.给出了几种主要的降水类型,分析了相应的大气可降水条件及其特征,并剖析了产生降水的大气动力条件.结果显示,地面降水中心通常并非出现在大气可降水的高值中心区域而是产生在其下风方向的某一区域.