基于地基微波辐射计的大气液态水及水汽特征分析

摘要

The liquid water and water vapor are important to the study of disastrous weather. High temporal and spatial resolution data of liq-uid water and water vapor can be obtained by ground-based microwave radiometer. Using the microwave radiometer data in 3 stations of Hu-bei, the temporal and spatial variations of water vapor and liquid water content retrieved by microwave radiometer are analyzed. Precipitable water vapor (PWV) obtained by microwave radiometer is firstly compared with the radiosonde observation, and the result shows that there is a good correlation between them with relatively small bias. In general, the vapor density (VD) decreases with height, and the vapor density below 2 km in rainy condition is lower compare with that in cloudy condition. The liquid water content (LWC) firstly increases with height and then decreases, and the peak is larger in rainy condition than in cloudy condition. A clear diurnal variation of PWV is found in the rainy condition, with a character of"one peak and one valley". The integrated liquid water (ILW) is volatile at night and has the peak value after midday. The ILW of JingZhou is significantly lower than that of WuHan and XianNing as water vapor is difficult to condense with the influence of terrain. In autumn and winter, the ILW in XianNing is higher than that in JingZhou and WuHan. The water vapor accumulates mainly below 2 km and condenses around 4 km height when precipitation.%大气液态水及水汽的探测对研究灾害性天气具有重要作用,地基微波辐射计可同时获取高时空分辨力的液态水及水汽资料.利用湖北省内三个测站的微波辐射计资料,分析了三站液态水及水汽的时空分布及变化特征.对比武汉站微波辐射计与探空得到的大气可降水量(PWV, precipitable water vapor)发现,两者偏差较小且相关性较好.水汽密度(VD, vapor density)整体随高度递减,2 km以下部分高度的VD在降水时要小于阴天时.液态水含量(LWC, liquid water con-tent)随高度先增后减,降水时其峰值高度明显高于阴天时.降水时,PWV的日变化呈现"一谷一峰"的特征,液态水总量(ILW, integrated liquid water)在白天先增后减,在午后出现峰值,在夜间变化波动较大.受地形影响,荆州液态水总量明显低于武汉、咸宁,咸宁ILW在秋冬季明显高于荆州、武汉.降水发生时,水汽主要在2 km以下积聚,之后被抬升至4 km左右高度凝结并降落.