内蒙古强冷空气时空变化特征及大气环流型分析

Spatio-temporal Characteristics and Atmospheric CirculationPatterns of Strong Cold Air in Inner Mongolia

【目的】为探究1981—2022年内蒙古强冷空气事件的气候特征及大气环流型。【方法】利用中国气象局逐日降水和日最低气温及NCEP/NCAR再分析数据集,对内蒙古强冷空气事件进行判别,并采用REOF及合成分析等方法对内蒙古强冷空气时空特征及大气环流型进行分析。【结果】就强冷空气事件线性变化趋势空间分布特征来看,2月强冷空气次数增加的站点最多。分析各区冷干型、冷湿型强冷空气次数,1区、2区冷干型强冷空气过程多于冷湿型,3区冷湿型强冷空气过程多于冷干型。长期变化趋势只有3区冷干型、冷湿型强冷空气次数都为减少趋势,1区、2区冷湿型强冷空气次数为增加趋势,1区、2区冷干型强冷空气次数为减少趋势。【结论】各区域形成冷干型强冷空气过程的主要条件是需要有西北气流影响该区域,而形成冷湿型强冷空气过程的主要条件是东南的暖湿气流输送到该区域。

To explore the climatic characteristics and atmospheric circulation patterns of strong cold air events in Inner Mongolia from 1981 to 2022,this paper identifies the strong cold air events in Inner Mongolia by using daily precipitation and daily minimum temperature data from China Meteorological Administration as well as the NCEP/NCAR reanalysis dataset.Besides,the spatial and temporal characteristics of the strong cold air in Inner Mongolia and the atmospheric circulation types are analyzed by the methods of REOF and synthetic analyses.The results show that,in terms of the spatial distribution of linear trends in strong cold air events,the stations with the increase in cold air events are mostly observed in February.Based on the analysis of occurrence frequency of cold-dry and cold-wet strong cold air events in different regions,Regions 1 and 2 have more cold-dry type events,while Region 3 encounters more cold-wet type events.The long-term variation trends indicate a decreasing tendency in the frequency of cold-dry and cold-wet types of strong cold air events in Region 3,while Regions 1 and 2 show an increasing trend in cold-wet type events and a decreasing trend in cold-dry type events.In summary,the primary condition for the formation of cold-dry type strong cold air processes in each region is the influence of northwest airflow,whereas the formation of cold-wet type strong cold air processes requires the transport of warm and moist airflow from the southeast.