新疆春季气温前后反相变化及其环流异常特征OA

Based on the monthly spring air temperature observations,NCEP/NCAR reanalysis data,and circulation indices in Xinjiang from 1961 to 2023,we studied the dominant modes of intraseasonal temperature variation in spring over Xinjiang and their corresponding circulation anomalies.The results show that over the past 60 years,spring temperatures in Xinjiang have increased significantly,with two dominant intraseasonal variation modes:uniform change and inverse phase.When the temperature in spring is uniformly warm(cold),the upper-troposphere zonal winds exhibit a north-south dipole pattern,the middle layer is positive(negative)like the East Atlantic-West Russia Pattern(EA/WR),an anomalous cyclone(anticyclone)develops over the Ural Mountains at lower levels,and the surface Eurasian cold high is weak(strong).When the temperature reverses during the season,key circulation systems including the subtropical westerly jet,the meridionality of the mid-to high-latitude circulation,geopotential height of the Ural Mountains and Western Siberia,the abnormal cyclone-anticyclone dipole distribution in the lower level,and the persistence and evolution of the Eurasian cold high,which affect the temperature fluctuation,are the reasons driving the temperature in phase and reversed-phase.Furthermore,the analysis shows that the Scandinavia Pattern(SCA),Asian Zonal Circulation Index(AZC),Atlantic-European Polar Vortex Intensity Index(AEPVI),East Atlantic-West Russia Pattern(EA/WR),Asia Polar Vortex Area Index(APVA),and East Atlantic Pattern(EA)have important effects on the intraseasonal temperature variability and can be used as important predictors for intraseasonal temperature fluctuations.