Abstract：The pressure and temperature parameters are the prerequisite for the precise precipitable water vapor monitoring based on the ground GPS. When lacking in the above meteorological data, the precipitable water vapor is firstly derived on the basis of the extrapolated pressure and temperature, and its precision is also analyzed. At the same time, the linear relationship from fitting between the precipitable water vapor and zenith total delay is used to get the precipitable water vapor. The conclusion shows that, the precision of the precipitable water vapor from fitting is higher thanks to the avoidance of the apriori error. So, once the empirical relationship is determined, we can monitor the precipitable water vapor using GPS in high precison.
