Atmospheric Precipitable Water Amount Retrieval And Its Preliminary Study UsingGround-based GPS Data

Water vapor in earth's atmosphere plays a crucial role for climate,dynamics of weather system,atmosphere environment, hydrology and space geodesy. However, the scarcity in water observation greatly restricts the development of these disciplines and understanding of water vapor.GPS technology provides a new means for sensing atmosphere with the advantages of real-time, continuity, high precision and unaffected by weather et al, which has become powerful supplementation for routine atmosphere sensing system.This paper discussed some problems about real-time retrieving absolute PWVwith high precision from local GPS network, including the choice of appropriate computation software and method, well determination and suitable zenith delay parameter.In order to guarantee the absolute value of PWV, appropriate remote assistant stations more than 500 km should be combined.In this thesis, how many remote stations is best choice has been studied first. And the end problem of real application in weather forecast are also discussed. Some useful methods are developed to eliminate the effects of tropospheric gradient by analyzing the changes of atmosphere in different seasons and different regions.Comparisons between GPS/PWV and radiosonde observations show that GPS/PWV retrieved by above method get better results. Atmospheric gradient's establishment syzygy position each direction is influential, moreover the different season, the different regional influence is different, therefore proposed when chooses the satellite station considers the climate difference .Meanwhile some tests are held to make the comparison of the Saastamoinen model with the Hopfield. The results showed that the general model's suitable region and the climatic conditions are very limited, climatic conditions special particularly high elevation area when actual use should the model localization. Practically, Sounding information in the application of very limited information is limited to the surface data.This paper have built the local correction models for dry delay and atmospheric weighted temperature on the basis of actual upper-air detecting data. The results show that the conclusion is satisfied.