基于地基微波辐射计遥感的天津大气水汽和液态水特征

Characteristics of atmospheric water vapor and liquid water over Tianjin identified by remote sensing data from ground-based microwave radiometer

利用2013年3月至2017年2月天津西青地基35通道微波辐射计观测资料,分析天津地区大气水汽和液态水特征。结果表明:天津地区各季节积分水汽和积分液态水的日变化趋势基本一致,均呈单峰型日变化特征,其中夏季最大,秋季次之,冬季最小。各季节积分水汽最大值出现在23:00时(北京时,下同)的概率均明显大于其他时次,夏季和冬季的积分液态水的最大值出现在14时的概率最大,春季和秋季分别出现在10时和13时的概率最大。天津地区水汽密度由地面至35km处逐渐减小,递减梯度由夏季、秋季、春季和冬季的顺序依次增大,各季节从15km往上日变化均不明显。1km以下,春季、夏季和秋季平均水汽密度的日变化曲线呈双峰型,主峰值分别出现在08时、11时和12时左右。冬季呈单峰型变化,峰值区出现在1216时。液态水密度随高度分层变化,夏季的液态水密度大值区(008014g m-3)为56km,在1820时出现最大值。秋季、春季和冬季液态水密度的大值区出现的高度为1535km,但数值依次减小,春季和冬季的最大值出现在05时前后,秋季则出现在02时左右。另外天津地区水汽、液态水与温度和降水量的变化趋势基本一致,除夏季0618时及冬季部分时次外,水汽与温度呈正相关。液态水与温度相关性较差,但与降水量呈正相关,全年液态水与降水量夜间的相关性大于白天。

The characteristics of atmospheric water vapor and liquid water in Tianjin were analyzed using the observation data from 35 channel microwave radiometers at Xiqing district from March 2013 to February 2017.The results show that daily variation trends of water vapor and liquid water over the Tianjin region are basically the same during the four seasons.The diurnal variation characteristics are unimodal,with the largest in summer,the second in autumn,and the smallest in winter.The probability that the maximum value of the integrated water vapor during each season appears at 23:00-00:00(Beijing time,the same below)is significantly greater than that at other times.The probability that the maximum value of the integrated liquid water in summer and winter appears at 14:00 is the highest,and the probability that appears at 10:00 in spring and at 13:00 in autumn is the highest.The water vapor density over Tianjin decreases gradually from the ground to 3.5 km.The decreasing gradient increases successively from summer to autumn,spring and winter.The diurnal variation is not significant from 1.5 km to 3.5 km in each season.The diurnal variation curve of the average water vapor density shows a bimodal pattern below the height of 1 km in spring,summer and autumn,and its main peak value appears at around 08:00,11:00 and 12:00,respectively.In winter,there is a single peak type change.The peak area appears between 12:00 and 16:00.The density of liquid water varies with the height of stratification.In summer,the high-density region of liquid water(0.08-0.14 g·m-3)is between 5-6 km,and its maximum value occurs between 18:00 and 20:00.The high-value areas of liquid water density in autumn,spring and winter are between 1.5-3.5 km,and the value decreases successively.The maximum value of liquid water density in spring and winter is around 05:00,while that in autumn is around 02:00.In addition,the variation trend of water vapor and liquid water in Tianjin is basically the same as those of temperature and precipitation.The water vapor is positively correlated with temperature except for the time from 06:00 to 18:00 in summer and part of the time in winter.Liquid water has a poor correlation with temperature,but a positive correlation with precipitation.Throughout the whole year,liquid water has a greater correlation with precipitation at night than during the day.