摘要
从计算大尺度热源和分析ＴＢＢ资料两个方面，阐述了１９９１年江淮梅雨期间降水性质与对流活动的季节性演变特征。结果表明：梅雨期间江淮上空３个强上升运动时段分别形成了３场暴雨，由暴雨释放的热量使江淮大气出现了３个时段的强加热；３场暴雨的降水性质呈显著的季节性演变，由第１场暴雨以锋面性降水为主发展到第３场暴雨异常强的对流性降水。文中详细分析了热源和水汽汇的时空分布特征，并从大气运动场和热力结构讨论了盛夏强对流降水期间积云对流以涡动形式对热量和水汽的强铅直输送作用。江淮地区ＴＢＢ值能很好地反映降水状况，雨期一致地对应于ＴＢＢ低于２５０Ｋ的时段。梅雨中后期东亚地区对流活动季节性地增强，带状对流区（特别是ＴＢＢ高负距平区）与雨带位置相符。对流带位置及对流活动强弱与西南暖湿气流活动密切相关，它很好地表征了东亚地区的低空急流（给积云输送热带对流大气）。梅雨期间对流带主要出现在江淮流域，但可在东亚范围内飘移。
Seasonal variability regarding the nature of precipitation and the activity of cumulus convection during the 1991 Meiyu season of Changjiang Huaihe River Basin (Jianghuai) has been investigated by calculating apparent heat source / apparent moisture sink and analyzing TBB data. It is found that three periods of strong ascending motion during the Meiyu season lead to three episodes of heavy rain, and the latent heat due to precipitation is of the sole heat source of the atmosphere over Jianghuai during the three rain episodes. The nature of precipitation shows distinct seasonal variability, from frontal precipitation of the first episode to the extremely strong convective precipitation of the third episode. The spatial and temporal distributions of Q 1 and Q 2 which describe the strong vertical eddy heat and moisture transport during the mid late stage of the Meiyu are presented in detail. In Meiyu season of Jianghuai, rainfall may be well reflected by TBB value, and rainy periods are usually corresponding to TBB values less than 250K. Evolution of TBB field also reveals the fact that the activity of cumulus convection strengthens seasonally, and cumulus zone of the third episode appears as a narrow belt which seems to be mainly determined by southwest airflow which provides water vapor and convective atmosphere for cumulus. In the whole Meiyu season, convection belt mainly stays in Jianghuai area, but for some short periods it may shift in the region of East Asia. Its locating in Jianghuai area or not results in the maintenance or break of Meiyu.
出处
《气象学报》
CSCD
北大核心
1997年第3期318-333,共16页
Acta Meteorologica Sinica
基金
国家自然科学基金
中日亚洲季风机制项目
关键词
暴雨
降水性质
对流活动
热量
Apparent heat source / apparent moisture sink, TBB data, Precipitation nature, Cumulus convection, Meiyu.
