| In this paper we used satellite data and ground humidity parameter (water vapor pressure) to retrieve the precipitable water in cloudless sky and cloudy sky. The precipitable water got from high levels sounding stations was chosen as the real value for tests. The region between 105°~115°E and 35°~40°N was chosen as the calculated zone for investigations.Under the cloudless conditions, the precipitable water was calculated by satellite data and ground humidity parameter respectively, and it was also calculated by the combinable satellite data and ground humidity parameter data. Research results were showed as follows:The distribution of the precipitable water retrieved from satellite data was of well spatial and temporal resolutions. The configuration of vapor field was quietly fine, whose distribution of 'hot centers' and 'wet centers' was obvious. The 'hot centers' were located at the high value zone of the split-window brightness and the wet ones were at the low zone correspondingly.Using the ground humidity parameter data, the precipitable water of single station was more accurate than the data retrieved from satellite data. But it was of low spatial and temporal resolutions compared with that retrieved from satellite data. There were also obvious 'hot centers' and 'wet centers' in the distribution of the precipitable water, yet the numbers of those centers were less than the retrieved data.Based on above discussions, a new method for calculating the precipitable water was put forward by combing the above both data. Conclusions indicate that the calculated water vapor fields were better than the former two methods. It was more precise of single point to interpolate into the whole discussed area, therefore, it was more practical.Furthermore, the precipitable water in cloudy sky was also calculated by the ground humidity parameter data. The calculated data were of high precision and low errors so that it was convenient to apply for investigations. |
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