THE VARIATIONS OF POLAR VORTEX AND SOUTH ASIA HIGH AND CHARACTERS OF NORTHERN ATMOSPHERE CIRCULATIONS AT 100HPA

The NCEP/NCAR re-analysis data and wavelet transform are used to study Polar Vortex and South Asia High. At the same time,the EOF analysis and long-term variation means are used to analyze 100hPa geopotential height in winter and summer. The results shows that Polar Vortex and SAH has similar periodic characters,both of which displaying 5-year and 20-year time scales,and the characters of precedent Winter Polar Vortex and SAH were especially similar to each other. But the trends of Polar Vortex and SAH are opposite. EOF analysis shows that the structure of the first mode and the second mode display differences between high latitudes and low latitudes in winter. Meanwhile,the trends of time coefficient of the first mode and precedent Winter Polar Vortex are consistent. To some extent,the structure of the first mode reflects the characters of the precedent winter atmosphere circulations. In summer,the first mode displays negatively at the entire 100 hPa geopotential height,and reflects abnormal characters generally. The second mode displays differences between high latitudes and low latitudes and reflects the variations of Polar Vortex circles in summer. It means that the abnormal changes of atmosphere circulation of the Northern Hemisphere have close relations with Polar Vortex and SAH. The long-term variations display negative trends in high latitudes but positive ones in subtropical anticyclonic regions in winter. Expect for north China,which displays negatively,other areas displays positively,in summer. Polar Vortex and South Asia High are related with the long-term variations of 100 hPa geopotential height. As it is known,Polar Vortex exists in every season,but South Asia High exits mainly in summer,and precedent Polar vortex can affect later atmosphere circulations. Therefore,it can provide some theories to forecast abnormal variations of SAH by studying the characters of Polar Vortex,especially precedent Polar Vortex.