1961—2010年我国冷空气的活动特征

利用1960—2010年我国384站逐日温度资料和NCEP/NCAR逐日再分析资料,分析了我国冷空气活动的频次、强度等特征。结果表明:我国单站冷空气呈北多南少、北强南弱的分布特征。按冷空气活动路径,北方分成3个区,它们在11月频次最多;南方以25°N为界分成2个区,它们在12月、1月频次较多,在年际尺度上该2区冷空气呈减少、减弱趋势。南北5个区冷空气活动频次的年代际变化不一致,但是各区冷空气活动的强度在20世纪60年代至80年代均呈年代际减弱。全国性冷空气活动频次在20世纪60年代和90年代显著减少,而北方冷空气活动频次的年代际变化不大。当欧亚大陆地面冷高压比正常年偏强(偏弱)、我国大部分地区温度比正常年偏低(偏高)、高层500 h Pa东亚大槽比正常年偏强(偏弱)时,当年冷空气活动的频次偏多(偏少)。

Activity characteristics of cold air in China from 1961 to 2010

Based on the daily surface temperature data at 384 stations of China and the NCEP/NCAR daily reanalysis data from 1960 to 2010,this paper analyzes the frequency and intensity characteristics of cold air activity in China.Results show that both frequency and intensity of cold air activity at single station in northern China are higher than those in southern China.Based on the invading routes of cold air,northern China is divided into three subareas,in which the most cold air activity occurs in November,and southern China is divided into two areas by 25°N,in which more cold air occurs in December and January.On the interannual scale,both frequency and intensity of cold air activity decrease.On the interdecadal scale,the frequency variations of cold air activity in the five areas are inconsistent,while the intensity variations weaken from 1960s to 1980s.The frequency of nationwide cold air activity decreases in both 1960s and 1990s,while the interdecadal variation of northern cold air activity frequency is weak.Compared with the normal years,when Eurasia surface cold high pressure strengthens(weakens),surface temperature in most parts of China decreases(increases) and East Asia trough strengthens(weakens) at 500 hPa,the frequency of cold air acitivity is higher(lower) in the corresponding years.