Comparative Analysis of Two Blizzard Processes in the South Slope of the Western Tianshan Mountains
This study used the data of conventional observation,FY-4A satellite and ERA5 reanalysis,and analyzed the causative factors behind two heavy snowfall events that occurred in Baicheng County from February 25 to 27,2010(process Ⅰ)and from April 1 to 4,2010(process Ⅱ).The results show that both snowstorms are caused by Central Asian low-pressure system,300 hPa westerly jet,500 hPa vortex(trough),850 hPa easterly jet,surface cold high pressure,cold front and vertical circulation over blizzard areas are the main dynamic mechanism of two snowstorms;water vapor is transported from west and southwest path,the strong convergence of water vapor at 700 hPa,during the period of snowfall,the extremes of TBB,the maintenance times of TBB less than-30℃ and the occurrence of TBB greater than-5℃ provide reliable indications for predicting the orders,duration and phase of snowfall.The differences of two snowstorms are as follows:process Ⅰ is characterized by the rapidly eastward-moving of the Central Asian trough with easterly jet streams confined to 850 hPa,the jet is weaker and locates southward.In contrast,Process Ⅱ is characterized by the slow eastward-moving of Central Asian vortex,significant easterly jets appear at 700 hPa and 850 hPa for a long duration,the jets are located in northern Aksu.Compared to process Ⅰ,the upward movement center of process Ⅱ is closer to blizzard center,process Ⅱ has stronger ascending motion intensity,the higher extension height and longer duration;there is more intense cold-warm convergence.Additionally,there is a more pronounced easterly water vapor transport with stronger convergence and a more prolonged duration.
blizzardsouth slope of western Tianshan Mountainscomparative analysisvertical circulationmoisture transport
万方数据
维普
