摘要
首先对比分析了三种测量水汽技术(地基微波辐射计、探空、GPS)之间的差异,得到地基微波辐射计与探空的差值为0.281cm,GPS与探空的差值为0.728cm,地基微波辐射计与GPS的差值为0.322cm。接着就地基12通道微波辐射计测量得到的水汽总量(简称PWV),分析了北京地区水汽在四个季节中的日变化特征。秋季日变化差为0.162cm,冬季日变化差为0.130cm,春季日变化差为0.229cm,夏季日变化差为0.276cm。另外,北京地区四个季节中水汽最大值/最小值出现频率最高的时间段呈现一定的特征。即四个季节中在北京时间00:00到00:59和23:00到23:59这两个时间段中,水汽出现最大值/最小值的概率较其他时间段都高,其中冬季在北京时间10:00到10:59之间出现最小值的概率最高。水汽总量PWV每小时变化率在四个季节中都存在这样的现象:出现正的水汽总量PWV每小时变化率的百分比与出现负的水汽总量PWV每小时变化率的百分比相当,几乎都为50%。最后就水汽与温度相关性做了分析,分别得到四个季节中各个小时水汽与温度的相关系数,结果显示各个小时水汽与温度的相关性在四个季节中,除了夏季从北京时间09:00到22:00为负相关外,其他时间段内都为正相关。而且各个小时水汽与温度的相关系数都按照秋、春、冬、夏的顺序递减。
Precipitable water vapor （PWV） is one of important green-house gases in the atmosphere. It affects the energy balance of the land-atmosphere system. The evolution of cloud and precipitation has a close relationship with the PWV. In the climate change,the PWV has a positive effect on temperature. Ground-based microwave radiometer can make all day unattended measurement of the PWV. Three different PWV measurements are compared. The PWV mean bias between the radiometer and the radiosonde is 0.281 cm. The PWV mean bias between the radiometer and the GPS is 0.322 cm. The PWV mean bias between the GPS and the radiosonde is 0.728 cm. In Beijing,there exist different diurnal variations in different seasons. The mean diurnal variation is about 0.162 cm in autumn,0.130 cm in winter,0.229 cm in spring,and 0.276 cm in summer. Moreover,the maximum PWV appears mostly at 0000 LST or 2300 LST in the four seasons. The minimum PWV is the same as the maximum PWV,except that the minimum PWV appears at 1000 LST in winter.The variation of PWV per hour decreases in the order of summer,autumn,spring and winter. Moreover,in every season,both percentages of the positive and negative PWV variations per hour are nearly 50%.The hourly correlations between the PWV and temperature are analyzed for the four seasons. The hourly correlation coefficients decreases in the order of autumn,spring,winter and summer. In autumn,spring and winter,all the hourly correlation coefficients are positive. However,in summer,the hourly coefficients are negative from 0900 LST to 2200 LST.
出处
《大气科学》
CSCD
北大核心
2009年第2期388-396,共9页
Chinese Journal of Atmospheric Sciences
基金
中央级公益性科研院所基本科研业务费专项基金项目"地基GPS斜路径水汽反演方法改进研究"
关键词
地基微波辐射计
水汽
日变化特征
温度
相关系数
12-channel ground-based microwave radiometer,precipitable water vapor （PWV）,diurnal variation,temperature,coefficient
