Application of precipitable water vapor from ground based GPS to three precipitation processes in Dalian region

Based on precipitable water vapor (PWV) data from GPS/MET observation network in Dalian, characteristics of PWV and its relationships with precipitation and precipitation intensity in Wafangdian, Zhuanghe and Changhai regions in 2001 were analyzed. According to the above analysis and physical quantity field as well as weather system, relationships of PWV variation with large-scale water vapor transport convergence and moisture convergence, and application of GPS to a rainstorm process were discussed. The results show that increase of PWV is often restricted by the local weather system. For a clear precipitation process, PWV changes and precipitation have a clear relation from beginning to end of the precipitation process. When water vapor transports from south to north, PWV increases gradually before precipitation begins. When it has large range moisture convergence at surface and upper level, and specific humidity reaches above 10g·kg^-1, PWV increases significantly in previous 4-5 hours of rainstorm. Main precipitation period corresponds to the peak value of PWV. Meanwhile, PWV increment has a significant relation with precipitation intensity.