蒙古高压和极涡中期过程对2010年疆北持续性降雪的影响

利用NCEP1再分析的逐日、逐月位势高度、海平面气压、风、温度、相对湿度资料与中国地面气候资料日值数据集(3.0)降水资料,分析了新疆北部2010年1-2月连续5次降雪过程以及蒙古高压和极涡对其的影响。结果表明:在充沛水汽条件下蒙古高压强而连续的爆发是导致2010年降雪极端异常的重要原因。该年蒙古高压平均强度为历年最强,在此次持续性过程中,存在5次蒙古高压的南北移动和5次蒙古高压强度与面积的振荡。且每一次降雪、降温过程前基本都存在蒙古高压南进、面积增大、强度增强。蒙古高压中心纬度超前新疆日平均温度1~3天的相关和蒙古高压强度和面积指数超前新疆北部日平均温度1~4天的相关均显著。研究极涡与蒙古高压二者关系发现,前期对流层高层极涡增强、极涡中心北移,有利于后期的蒙古高压增强增大且中心南移。

Impact of Mongolian High and Polar Vortex Mid-term Synoptic Activity on Continuous Blizzard in North Xinjiang in 2010

Based on the NCEP1 reanalysis of daily,monthly geopotential height,sea level pressure,wind,temperature,relative humidity data and daily precipitation data of China’s surface climate data multi-day data set V3. 0(SURFCLICHNMULDAY),the mid-term synoptic process characteristics of the 5 continuous snowfall episodes in northern Xinjiang province during January to February in 2010 and the influences of the surface Mongolian high pressure and the upper troposphere polar vortex on them are analyzed. The results show that the strong and continuous outbreak of Mongolian high pressure under abundant water vapor conditions is an important cause of extreme snowfall in 2010. In this year,the average intensity of Mongolian high pressure was the strongest in the historical data. During this continuous snowfall processes,there were 5 times north-south direction movements of the surface Mongolian high pressure’s center and 5 times oscillations of its intensity and area.In addition,before each snowfall and cooling process,the center of Mongolian high pressure at surface moved southward,and the area of Mongolian high pressure expanded and the intensity of Mongolian high pressure increased. Lead/lag correlation between the latitude of the surface Mongolian high pressure center and the daily average temperature of Xinjiang area is significant,and the number of days of leading is 1~3 days. Lead/lag correlation between the intensity of the surface Mongolian high pressure and the daily average temperature of Xinjiang area is significant,the number of days of leading is 1~3 days. Lead/lag correlation between the area of the surface Mongolian high pressure and the daily average temperature of Xinjiang area is significant as well,and the number of days of leading is 1~4 days. The article also selects the years of abnormal large snowfall in the historical records to study the lead-lag correlation between the upper troposphere polar vortex circulation index and the surface Mongolian high pressure circulation index,study found that the characteristics of the multi-year synthesis results are basically similar to the exceptional year 2010. The synthesis results further verify the correlation between the surface Mongolian high pressure and the upper troposphere polar vortex,that is,the enhancement of the intensity and the northward movement of the center of polar vortex at the upper troposphere in the early stage,which was conducive to the enhancement of the intensity,the expansion of the area and the northward movement of the center of the Mongolian high pressure at surface in the later stage.