关键词: 新疆西部, 暴雪, 中尺度特征

Abstract:

Based on the hourly observation data from the conventional and automatic weather stations, initial fields of ECMWF with 0.25°×0.25° spatial resolution, infrared cloud images of FY-2C, Doppler radar products and NCEP FNL reanalysis data with 1°×1° spatial resolution, the snowstorm process occurring on 28 January 2014 in western Xinjiang was analyzed. Results showed that the snowstorm district located in the front of mesoscale short wave trough, the overlaying area of strong convergence in low level and divergenc in high level of the mesoscale systems, the edge of mesoscale cold cloud cluster moving slowly eastwards and the front of the maximum TBB gradient region. The mesoscale systems causing the snowstorm were the convergence lines, shear lines and cold front, and the amounts and duriation of mesoscale cold clouds were positively correlated with snowfall. Radar products displayed that the snowstorm occurred in the echo band with the reflectivity factor more than 15 dBZ, and the strongest echo region was essentially coincident with the snowstorm center.The stronger warm advection, vertical wind shear and convergence appeared over the snowstorm region.The thickness of low-level jet was significantly positive correlated with precipitation, and the lowest height of low-level jet had close relationship with the start time of snowfall and the strong snowfall period.

Key words: western Xinjiang, snowstorm, mesoscale characteristics