Abstract:

Based on the detection data of airborne microwave radiometer GVR (G-band water Vapor Radiometer) and Hotwire Liquid Water Content Sensor, cloud top brightness temperature of FY-2E satellite, radar reflectivity at Tanggu station of Tianjin and FNL reanalysis data from NCEP (National Centers for Environment Prediction) and NCAR (National Center for Atmospheric Research) on 20 November 2016, the distribution characteristics of water vapor and liquid water for typical stratiform clouds in Tianjin area are analyzed. The results show that the liquid water path of stratiform clouds in Tianjin area decreases with the increase of height from the bottom of clouds, and it drops to 0 mm at the height of ice cloud and above. The integrated water vapor content gradually decreases from the ground with the increase of height, and its value holds at 0.3-0.5 cm during the level flight at 3 500 m above clouds. The density of liquid water increases firstly and then decreases with the increase of height. The liquid water detected by GVR above the cloud base (900 m) is supercooled water. During the ascent of aircraft, the supercooled water is mainly distributed at the height of 900-2 400 m, and the maximum density is 0.63 g·m^-3. During the descent of aircraft, the supercooled water is mainly distributed at the height of 900-1 600 m, and the maximum density is 0.78 g·m^-3. Compared with the Hotwire Liquid Water Content Sensor, GVR can better reflect the supercooled water content of clouds, the height and thickness of the supercooled layers. The water vapor in Tianjing area mainly comes from the advection transport. The water vapor density increases continuously at the height of 400 m, and accumulates obviously near the cloud base, and then decreases rapidly. Within the height of 1 400-3 000 m, the water vapor density fluctuates little. With the approaching of precipitation, the maximum value of water vapor density and its corresponding height increases during the descent of aircraft, and the thickness of the high water vapor density layer increases, which can provide some references for precipitation prediction and weather modification.

Key words: airborne microwave radiometer, stratiform cloud, water vapor, cloud liquid water, distribution characteristics

摘要：

基于2016年11月20日机载微波辐射计GVR（G-band water Vapor Radiometer）和热线含水量仪探测资料以及FY-2E卫星云顶亮温、天津塘沽站雷达组合反射率、美国国家环境预报中心（National Centers for Environment Prediction，NCEP）/国家大气研究中心（National Center for Atmospheric Research，NCAR）FNL再分析资料，分析天津地区典型层状云水汽和液态水分布特征。结果表明：层状云的液态水路径自云底向上随高度上升而减小，到达冰云高度后减至0 mm，而积分水汽含量自地面向上随高度上升逐渐减小，在云上3 500 m高度平飞过程中稳定在0.3~0.5 cm。液态水密度随高度上升先增后减，在云底（900 m）以上GVR探测的液态水均为过冷水，在上升过程中过冷水主要分布在900~2 400 m高度，密度最大为0.63 g·m^-3，而在下降过程中主要分布在900~1 600 m高度，密度最大为0.78 g·m^-3。相比热线含水量仪，GVR能更好地反映云中过冷水含量及过冷层高度和厚度。水汽主要源于平流输送，水汽密度在400 m高度向上不断增大，在云底附近明显积聚后迅速减小，在1 400~3 000 m高度波动变化。随着降水的临近，飞机下降阶段的最大水汽密度增大且高度上升，水汽大值层厚度增大，可为降水预报及人工影响天气提供一定参考。

关键词: 机载微波辐射计, 层状云, 水汽, 云中液态水, 分布特征