河西走廊东部寒潮时空变化特征及典型个例分析

利用1986—2015年河西走廊东部5个气象站逐日气温、大气环流特征量和2016年5月常规天气图和物理量场，分析了河西走廊东部寒潮时空分布及其与大气环流特征量的关系和2016年5月3次寒潮天气过程天气成因。研究表明：河西走廊东部寒潮频次由北向南减少，中部最少；寒潮频次年际差异较大，总体呈下降趋势；寒潮主要出现在1—5月和10—12月，频次站次4月最多，6月最少，春季寒潮频次最多；寒潮最早出现在9月1日（永昌）、最晚出现在6月7日（乌鞘岭）。月寒潮频次与月亚洲、北半球的极涡面积和强度、北极涛动、亚洲经向环流和冷空气指数呈显著正相关，与北半球极涡中心纬向位置和强度、东亚大槽强度、西藏高原1和2指数呈负显著相关，前一月亚洲、北半球极涡面积和强度、北半球极涡中心强度、北极涛动指数对月寒潮预报预测具有良好的指示意义。使用多元回归建立寒潮月频次预报方程，通过了=0.1显著性水平检验。2016年5月3次寒潮天气均与极涡中心偏强有关，前期升温明显、高空强盛冷平流强盛、地面冷高压强烈是造成三次寒潮天气的主要原因，500 hPa横槽转向南压造成的降温幅度比小槽东移更大、影响范围更广。

Spatiotemporal variation and typical cases analysis of the Cold Wave in Eastern Hexi Corridor

Based on daily temperature, atmospheric circulation characteristics and conventional observation data and physical quantity fields, the spatiotemporal variation of cold wave and the relationship between cold wave and atmospheric circulation characteristics, and the causes of three cold wave processes in May 2016 were analyzed in eastern Hexi Corridor during 1986-2015. Research showed that the cold wave frequency decreases from north to south, central was the least. The inter-annual variations of cold wave frequency was larger, and showed a decreasing trend. The cold wave occurred mainly from January to May and from September to December, the mos was in April, the least in June, and the spring frequency was the most. The earliest cold wave appeared on September 1(Yong Chang), and The last cold wave appeared on June 7(Wu Shaoling). The monthly cold wave frequency was positively correlated with the Asia and Northern Hemisphere Polar Vortex Area and Intensity Index, Arctic Oscillation, Asian Meridional Circulation and Cold Air Activity Index, and negatively correlated with the Northern Hemisphere Polar Vortex Central Latitude and Intensity, East Asian Trough Intensity Index and Tibet Plateau Region 1, 2 Index. The Asia and Northern Hemisphere Polar Vortex Area and Intensity, Northern Hemisphere Polar Vortex Central Intensity and Arctic Oscillation Index of the previous month had a better indication for prediction of the cold wave. Multiple regression forecast equation of cold wave monthly frequencies was established, and passed significance level test of = 0.1. The three cold wave weather in May 2016 were related to the strong polar vortex center. Temperature increasing on early, strong cold advection in upper air and cold high pressure on ground were main reasons of the three cold wave weather. The 500 hPa transversal trough turning southward caused larger cooling range and wider influence range that that of small trough eastward.