利用TRMM PR和IGRA探测分析的拉萨降水云内大气温湿廓线特征  

Analysis of Atmospheric Temperature and Humidity Profiles within Precipitation Cloud in Lhasa Measured by TRMM PR and IGRA

作　　者：王梦晓 王瑞 傅云飞[1] WANG Mengxiao;WANG Rrui;FU Yunfei(School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China)

机构地区：[1]中国科学技术大学地球与空间科学学院

出　　处：《高原气象》2019年第3期539-551,共13页Plateau Meteorology

基　　金：国家自然科学基金项目(91837310);公益性行业(气象)科研专项(GYHY201406001)

摘　　要：利用热带测雨卫星测雨雷达(TRMM PR)降水回波反射率因子廓线(降水率廓线)与全球探空大气温湿廓线(IGRA)的多年融合资料,研究了青藏高原拉萨站夏季降水结构及相应的大气温湿结构特征。结果表明,该站降水回波反射率因子分布在17~45 dBz,大部分小于26 dBz;回波顶高度达17 km,呈现“瘦高”外形;相应的大气低层湿润,降水云内大气并非饱和,但温度露点差比全部状态时的值小。深厚降水系统的回波外形也呈现“瘦高”,按照降水率随高度的非线性变化,其垂直结构可分为三层,而浅薄降水系统的垂直结构呈现一层,即平均降水率斜率随高度呈对数线性变化,最大平均降水率(0.7 mm·h^-1)出现在地面。深厚降水与浅薄降水云体内400 hPa高度(7.5 km)上下的露点温度递减的速率不同。降水云体内的零度层高度大约6.3 km,但PR没有探测到零度层亮带。统计结果还表明拉萨探空站及附近的大气可降水量为20.89 mm·d^-1,降水转化率为27.0%,深厚降水系统的降水转化率是浅薄降水系统的2.9倍,深厚降水系统和浅薄降水系统的CAPE值分别为1941.7 J·kg^-1和1451.8 J·kg^-1。本研究结果为模式模拟青藏高原降水云内的温湿结构提供了观测依据。The atmospheric temperature and humidity profiles of precipitation cloud reflects the structure characteristics of precipitation cloud. In order to reveal the profiles inside the precipitation clouds of Lhasa in Qinghai-Tibet Plateau, the multi-year merging data of the precipitation profiles derived from the Tropical Rainfall Measuring Mission (TRMM)Precipitation Radar (PR)and the temperature and humidity profiles issued by the Integrated Global Radiosonde Archive (IGRA) are analyzed. The results show that the precipitation echo reflectivity factor is distributed between 17 and 45 dBz, most of which is less than 26 dBz. The echo height of the storm top reaches 17 km, presenting a ‘thin and tall’ appearance, corresponding to wetness but unsaturation in the lower atmosphere. However, the difference between the temperature and dew-point temperature within such precipitating clouds is smaller than its climatic value. The echo shape of deep precipitation system also presents "thin and tall" appearance. According to the nonlinear variation of rain rate with height within deep precipitating system, its vertical structure can be divided into three layers. While the vertical structure of shallow precipitating system presents one layer, that is, the slope of rain rate varies logarithmically linearly with height, and the maximum average rain rate (0.7 mm·h^-1) appears on the ground. The lapse of dew-point temperature is different in deep precipitation system and shallow precipitation system above and below the height of 400 hPa (7.5 km). The altitude of the melting layer in the precipitation system is about 6.3 km, but no brightness band is detected by PR. The statistical results also show that the atmospheric precipitable precipitation is 20.89 mm·d^-1 in Lhasa sounding station and its vicinity, the conversion rate of precipitation system is about 27.0%. Probably, the conversion rate of deep precipitation system is 2.9 times higher than that of shallow precipitation system. Besides, The CAPE of the deep precipitation

关 键 词：热带测雨卫星测雨雷达 降水廓线 温湿廓线 深厚降水 浅薄降水 

分 类 号：P407.2[天文地球—大气科学及气象学]