Inversion of precipitable water vapor in Hongkong

GPS data of August in 2004 obtained from 4 sites in Hong Kong GPS/MET network has been used to inverse the precipitable water vapor. The inversed GPS integrated water vapor has 1.44 mm RMSE and 0.97 mm BIAS compared with that from radiosonde data in Hong Kong Observatory, which shows good agreement between them. In this paper, we analyze the temporal and spatial change of Hong Kong summer water vapor using inversed GPS PWV, and have studied the relations of integrated water vapor with the average temperature, precipitation and ground vapor pressure. The results show that: there exists obvious temporal and spatial change of PWV, and for stations with close basic geographic location, it is obvious of the impact of altitude that the PWV in mountain station is lower than that in plain point under normal circumstances; ground vapor pressure has a good correlation with PWV; there often comes forth a precipitation process when the PWV increases rapidly, but there is no obvious correlation between the amount of integrated water vapor and the size of precipitation, and so the average amount before, the increase range in short time, and the maximum value of PWV should be considered in the precipitation forecast.