Different Morphological Distribution Of The Stratospheric Polar Vortex And Its Relationship With Weather And Climate In China

In recent years, the interaction between stratosphere and troposphere, especially theimpact of the significant abnormal of the stratosphere on tropospheric climate change ispaid more and more attention. Using of NCEP/NEAR reanalysis data and thetemperature and precipitation data of160stations in China provided by the NationalClimate Center, the diagnostic statistics and other analysis methods are used in thispaper. The changes in the polar vortex, especially the relationships between theMorphological Changes of the polar vortex and temperature and precipitation in winterin china, and the impact process and mechanisms of planetary wave propagation on theMorphological Change of the Stratospheric Polar Vortex are discussed. The mainconclusions are as following:(1)In these years while the polar vortex is relatively strong, the temperature inNorth China and East China especially in Northeast china is higher than that in yearswhile the polar vortex is relatively weak. At the same time the temperature is lower inmost Southwest China. But it has little change in Yangtze River area and South China.And the precipitation is above normal in southern region especially in mid-downstreamarea of Yangtze River and South China, but below normal in the North China. Besidesthese, it can be found that the potential height of500hPa is higher in the middle-highlatitudes and lower in the high latitudes while the polar vortex is relatively strong. Thecirculation implies that the East Asian Winter Monsoon and East Asian trough is weakercorrespondingly. Under this situation, the cold air gathered around the polar and warmair flows to inland region, which causes the higher temperature in East China and Northeast China, and more precipitation in the southern region and the Yangtze Riverarea.(2) The significant areas, which the correlation coefficient between the deflectionintensity index (the extent of the polar vortex moves toward the Eurasia) in January andthe temperature of China is significantly positive, is mainly located in northeast China,northland in the north china, eastern coastal China and the central and north Xinjiang.Compared with the January, the obviously positive correlation region of the temperaturein February is smaller, which is mainly located in northeast China. The significantlypositive correlation between the deflection intensity index and the precipitation inJanuary is mainly located in south of north China, central China and west of east China,the negative correlation locates in central Xinjiang. Compared with the January, theobviously positive correlation region of precipitation is in central China and it extendsto northwest and southeast of the central China. The circulation background field showsthat the East Asian trough and East Asian winter monsoon are obviously reduced in theEurasian polar vortex years in January. The departure of the southeast wind isremarkable in Central and eastern China which causes the warm and humid air to movetoward the northwest of China easily. And the departure of the north wind is remarkablein the north region of the lake Baikal, which makes cold and warm air’s meeting areasmove to north more than normal years. Also the lower humid air transmits upwardobviously. The correlation between the deflection intensity index (the extent of the polarvortex moves toward the North America) and the meteorological elements in Januaryand February are very small, only a few station through a significant test. It is explainedthat North America polar vortex years has a little effect on temperature and precipitationin china. The analysis of the circulation background supports the conclusion.(3) Planetary waves activity can lead to the stratospheric polar vortex deflectionand morphological changes. In the process of the deflection of the polar vortex to theEurasia, the amplitude and phase of wavenumber1increases gradually, the peak islocated in the Western Hemisphere, wave activity lean to the east with height increasesin vertical. And the wave amplitude of wavenumber2is smaller than wavenumber1and decreases, wave activity also lean to the east with height increases in vertical. Whilein the process of the deflection of the polar vortex to the North American, the amplitudeand phase of wavenumber1decreased sustained, the peak is mainly located in theEastern Hemisphere and the wave activity gradually shift from lean to the eastward tolean to the westward with height increases in vertical. The amplitude of wavenumber2increases gradually，the wave activity mainly lean to the westward with height increases in vertical. From the changes of the E-P flux, there are clear differences in the polarwaveguide between the two different forms of pre-deflection process of the polar vortex.In the process of the deflection of the polar vortex to the Eurasia, the polar waveguideof the wavenumber1enhance abnormally but that of the wavenumber2showeddecrease. However, in the process of the deflection of the polar vortex to the NorthAmerican, the polar waveguide of the wavenumber1decreases abnormally, even polarspread upward into the waveguide propagates down; The polar waveguide of thewavenumber2showed clearly enhance.