The Relationship Between The Cold Wave Frequency In Northern China And The Change Of Polar Vortex

Based on NCEP/NCAR reanalyzed data of Geopotential Height, temperature date and zonal wind data and ECMWF the ground temperature data of the2m during1979-2013,74circulation index date provided by National Climate Center. This paper has studied the space-time distribution of cold wave frequency in the north of China during1979-2012.By calculating the polar vortex area index and intensity index, this paper has analysised the polar vortex factor and the relationship between the cold wave frequency in the north of China,and get the following conclusion:(1) In the north of China,cold wave activity begins in September and ends in May of the second year, and the most active cold wave happens activity in November and March.In the recent34years, cold wave activity which happens in Inner Mongolia, northeast China, northern Xinjiang is most active.(2) In the spring and winter of the recent34years, cold wave frequency in central and western Inner Mongolia is increasing, this phenomenon is more significant in spring. In spring and autumn, cold wave frequency has declined significantly in the northeast China,Hebei,the north of Shanxi,and Shandong.In autumn, cold wave frequency has declined significantly in the northern China and Gansu, but in winter there has been a significant upward trend.(3) The polar vortex area and intensity showed a trend of decrease during the last34winter half year.The polar vortex intensity trend of decreased more significantly than The polar vortex area.The polar vortex area showed a trend of decrease in autumn,winter and spring. Trend of decreased more significantly in autumn.The polar vortex intensity showed a trend of decrease in autumn,winter and spring. Trend of decreased more significantly in winter.(4) The area of polar vortex in Asia showed a trend of decrease during the last34winter half year.A increasing tread of the area of polar vortex in Asia recent years in autumn,winter and spring.The area of polar vortex in Asia rose significantly form2000in winter.The intensity of polar vortex in Asia showed a trend of decrease during the last34winter half year.The intensity of polar vortex in Asia rose significantly form2004in winter.(5) The frequency of cold wave relations with polar vortex in Asia is better than the relationship between the index of polar vortex. In autumn Asian polar vortex area index and the frequency of cold wave relationship more closely, is more consistent positive correlation. In winter Asian polar vortex strength index and the frequency of cold wave relationship more closely, is more consistent positive correlation.In spring relationship Asian polar vortex strength index of cold wave frequency more closely, there are significant regional differences in the distribution of the correlation coefficient.(6) In autumn Asian polar vortex area of positive (negative) anomalies the area of Lake Baikal and Barr kersh Lake temperature is low (high) at850hPa. In winter Asian polar vortex strength positive (negative) anomalies in the North of our country at high latitudes temperature is low (high) at850hPa, high(low) temperature low latitudes.(7) Temperature at850hPa and the frequency of cold wave SVD analysis showed that the relationship between the area of Lake Baikal and Barr kersh Lake temperature and cold wave frequency is negative correlation in autumn.In winter the relationship between temperatures and high latitudes and cold wave frequency is negatively correlated, low-latitude regions temperature and cold wave frequency is positive correlation.