This paper mainly discusses how to determine the optimized strategy for retrieval of Precipitable Water Vapor (PWV) with high accuracy from tropospheric zenith wet delay using ground-based GPS receivers. GPS analytical network are constructed on the base of two observation sites in Antarctica in 1999 and several IGS sites. Tests are conducted to study the performance of different network sizes and different schemes parameters. A high-accuracy GPS processing software package GAMIT/GLOBK is utilized; multiple schemes are adopted for searching the optimized parameters for accurate PWV. After having running GAMIT/GLOBK of all test combination, the results are analyzed by Baseline Repeatability Rate(BRR) and bias between calculated GPS water vapor and actual water vapor. The primary achievements and conclusion are reached including the optimal IGS sites involved, network configurations, elevation cut-off angles, processing periods, knots position.
Weather Satellite data has great potential for Precipitation forecast which plays an important role in flood disaster monitoring. In this paper, the GMS-5 infrared cloud imagery combined with surface temperature data for two years in Binjiang reaches of Guangdong province in China is used to study the relationship between infrared cloud imagery and surface rainfall rates. First, parameterization estimate of infrared cloud imagery is made one the base of atmospheric probing principle, then some parameterization estimate result have been obtained under different analysis field from 3×3 to 15×15 pixels. The result shows:1 there exist obvious correlation between the probability of rain and parameterization estimate such as average brightness temperature(Tb), brightness temperature variance(fc), equivalent cloudage(CN),brightness temperature area index(A1--the first A5--the fifth grade, A6-the sixth grade );2 The rainfall intensity increase with Tb and f and CN, and that it decrease with Tb and A1.Finally,the prediction empirical formula of rainfall intensity has been established by means of optimized subclass regression under different analysis field. The following formula is made under analysis field of 11×11 pixels. The statistical result shows that the average precision of rainfall intensity is about 80% using infrared cloud imagery parameters and the size of analysis field has slight effect on it. If the rainfall intensity reached the storm standard, the flood alarm would be sent out.