On The Interannual Variation Of Temperature Difference Between Polar And Equatorial Regions In Association With Anomalies Of East-Asian Climate

Based on NCEP/NCAR reanalysis data we develop an index of the Temperature Difference between the Polar and Equatorial Regions (TDPE), and investigate the interannual variability of the index (ITDPE-S) at2-m height above surface in relation to winter rainfall and temperatures over Eastern Asia.(1)In winter, results suggest that ITDPE-S is able to reveal the remarkable increase in winter surface temperature at boreal high latitudes during global warming, with4-8year periodic variation found on its interannual scale. The ITDPE-S is in good correlation to winter rainfall and temperature of Eastern Asia. As the index is larger (smaller), the winter precipitation increases (decreases) over NE China, Xinjiang, Hexi Corridor, the Sea of Japan, the South-China Sea and the Philippines, corresponding to the drop (rise) in winter mean temperature in the northern and northeastern parts of China. Further study discovers that in the higher-valued ITDPE-S year the anomalous vapor in East-Asian mid latitudes comes mainly from the western North Pacific and the vapor related to the anomaly of rainfall at the low latitudes has its origin mainly in tropical oceans. Horizontal temperature advection-caused anomalous reduction of temperature can be employed to explain partially the abnormally lower mean temperature in winter at mid latitudes of Eastern Asia.(2)In summer, ITDPE-S shows its increasing trend in late2000s, with4year periodic variation found on its interannual scale. The ITDPE-S is in geographical correlation to summer rainfall of Eastern Asia, just in the Tibetan plateau has positive correlations. The region of positive correlations with temperature appears in the Yangtze river basin,especial in the middle and lower reaches, in other word, As the index is larger, the middle and lower reaches of the Yangtze river easily to appear hot whether. Horizontal and vertical temperature advection-caused anomalous increase of temperature can be employed to explain partially the abnormally higher mean temperature in summer at middle and lower reaches of the Yangtze river.(3)In spring and autumn, The ITDPE-S also has4to8year periodic variation found on its interannual scale, but both appear on the time is not consistent, the spring is1970s to1990S, the autumn is in the1980S. In spring, the ITDPE-S is significantly correlation to precipitation in east Asia less than the other seasons, beasaus of both high and low troposphere exists anticyclone circulation structure in east Asia. In autumn, the ITDPE-S significantly correlated with precipitation in low latitudes are similar whit in winter. In spring, the ITDPE-S is significantly associated with surface temperature of east Asia in south of China to the south China sea. In autumn, the ITDPE-S is significantly negative correlation to surface temperature in middle east China, especially the huaihe river. The whole troposphere atmosphere heating can make part of the explanation on those surface temperature anomalies. These results are of importance to understanding in depth the formation mechanisms and the effect of anomalies of atmospheric circulations.