Water Vapor Transport Characteristics During Typical Rainstorm Events Around Westerlies Continental High in Hami Area, Xinjiang
In this study, NCEP/NCAR FNL 0.25°×0.25° reanalysis data, GDAS 1°×1° reanalysis data, the fused hourly precipitation of satellite and radar, conventional weather data of Xinjiang, FY-2G satellite data, the GPS-observed PWV data and the HYSPLIT trajectory model are used to conduct an in-depth analysis of extreme precipitation events that occurred in the southeastern Hami Area of Xinjiang on 31 July 2018 (hereinafter referred to as the 31 July process) and in the northern Hami Area on 8 August 2016 (hereinafter referred to as the 8 August process). Based on calculations of water vapor transport stream function, potential function, water vapor transport trajectories, water vapor budge, the characteristics of large-scale water vapor transport and convergence during two severe rainfall events are analyzed. The results show that the two events both occurred in the situation of abnormal continental high, which provided a favorable circulation background for long-distance water vapor transport. The water vapor transports in both of the severe rainfall events consisted of three stages, and the Hexi Corridor water vapor transport contributed to the water vapor supply in both events. Before and during the 31 July process, affected by the easterly water vapor transport channel, there was an obviously humidification at stations of Hami Area and Gansu Province from southeast to northwest. The transport and supplement of water vapor from low latitude provided an abundant water vapor supply for the short-time severe rainfall in southeastern Hami Area. Comparatively, before and during the 8 August process, the water vapor transport channel from northern Tibetan Plateau to southern Bazhou Area in Xinjiang was established. The water vapor in Tibetan Plateau was carried toward north, joining in the water vapor taken by southwest airflow in front of the trough. At the same time, with the low-level water vapor from Hexi Corridor, three humidification processes were triggered in northern Hami Area.