Three zenith hydrostatic delay (ZHD) models of Saastamoinen

Hopfield and Black are adjusted by using sounding data and GPS/MET observations from Nanchang and Ganzhou in 2010. These adjusted ZHD models not only reduce the model bias

but also improve the accuracy of ZHD. Compared with old ZHD models

the improved ZHD models are much closer to the sounding observations because they yield smaller bias and standard deviation from sounding data. Based on the GPS PW from Hopfield ZHD model (which has minimum bias)

the typhoon “Haikui” was analyzed during 7-11 August 2012 when it influenced northeast of Jiangxi. Results showed that the precipitation occurred two hours after GPS PW exceeding 60 mm

became much heavy when GPS PW was high and finally came to the end when the GPS PW was less than 60 mm. In this paper

the variation of GPS PW in Jingdezhen located northeast of Jiangxi was diagnosed using water-vapor budget equation. Results showed that in the early stage of typhoon's influence on Jiangxi，the specific humidity advection was the main cause for the increase of GPS PW. In the middle stage

the specific humidity advection weakened and the convergence of horizontal wind became the main cause for the increase and maintenance of GPS PW.  In the late stage

the convergence of horizontal wind reduced rapidly and the water vapor consumed by rainfall was the main reason for the decrease of GPS PW.