Characteristics of GPS-retrieved precipitable water vapor in different precipitation types

The precipitable water vapor (PWV) data are retrieved from the ground-based Global Positioning System (GPS) observational network together with the automatic weather stations in Chengdu region during the period of August 21, 2007 to November 30, 2008. The GPS-retrieved PWV data are analyzed for diurnal cycle characteristics as well as for different precipitation types including the summer heavy rainfall, the autumn continuous rain and the winter snow-rainfall. The result shows that storms occurred in different seasons correspond the distinct PWV. For example, the summer storms are associated with the change of PWV values from peaks to troughs. The opposite PWV change characteristic to the summer heavy rainfall is found at the end of summers. The result suggests that the change ratio of PWV values before a rainfall event may well indicate the intensity of subsequent heavy rainfalls. Significant variations in PWV ratios during the autumn continuous rain can potentially predicate the beginning or the ending of a rainfall event. The real-time consecutive GPS-retrieved PWV data can thus be used in operational precipitation forecasting.