Abstract: The evolution features of GPS-PWV in a persistent heavy snowfall process in the Tianshan Mountains from November 6 to 9, 2012 were analyzed using the GPS Perceptible Water Vapor (GPS-PWV) observations derived from the ground-based GPS network in the Tianshan Mountains, reanalyzed data and observed precipitation data from an automatic weather station. The results indicated that the variation trend of GPS-PWV in the Tianshan Mountains had an indication effect on snowfall. The value of GPS-PWV was increased continuously and obviously in more than ten hours prior to snowfall, and the amplification of GPS-PWV equaled the average monthly precipitable water vapor in recent ten years. Snowfall started within 3 hours before or after GPS-PWV was increased to its maximum. The high value of GPS-PWV in spatial distribution coincided with the snowfall areas. With water vopar converging and accumulating, GPS-PWV was increased with the time. Along with water vapor moving into Xinjiang with westerly wind, GPS-PWV was significantly increased from the west to the east. The temporal and spatial evolution characteristics can be used to accurately indicate the characteristics of water vapor.

Key words: ground-based GPS Perceptible Water Vapor, heavy snowfall, circulation pattern, Tianshan Mountains, Xinjiang