2017 年秋季黄河源区连阴雨成因分析.

In this paper, the analysis was carried out for the circulation background, water vapor characteristics and energy field during a continuous autumn rain process from September 22 to October 4, 2017 in the source region of the Yellow River. The results indicate that the anomalous changes in the south Asian high and the subtropical high made the atmospheric circulation change significantly over the same period. The continuous convergence of the northern cold air and the warm wet air that come from the periphery of the subtropical high led to the occurrence of this continuous rain weather. The strong southerly flow of the west side of the subtropical high continuously transport water vapor from the western Pacific and the South China Sea to the source region of the Yellow River and the water vapor convergence is formed on the 500-400 hPa layer. When the specific humidity of 500 hPa layer is more than 4 g/kg, strong precipitation is easy to occur in the source region of the Yellow River. During the continuous rain period, a large amount of unstable energy accumulates in the lower layer (mainly below 400 hPa), which provides advantageous thermodynamic conditions for the continuous rain. [ABSTRACT FROM AUTHOR]