Influence of Atmospheric Circulation Anomalies in the Southern Hemisphere on May Precipitation in Yunnan

Based on NCEP/NCAR monthly global reanalysis data and May precipitation of 124 meteorological stations in Yunan during 1961 to 2006,this research reveals atmospheric circulation of the southern hemisphere from January to April influences on May precipitation of Yunnan.The results show there was a significantly positive correlation between the north line of Antarctic Circumpolar Wave in January and May precipitation in Yunnan,and in January and February,the influencing significant key area was located in the southern hemisphere mid-latitude westerly belt,when the southern hemisphere mid-latitude westerlies geopotential height was higher(lower),May precipitation would be more(less).In March,the key area was located in the Antarctic,when the Antarctic polar vortex geopotential height was higher(lower),May precipitation would be more(less).In April,southern hemisphere middle and high latitude circulation influence weakened,but influences of tropical Pacific enhanced,when the Southern Oscillation in the positive(negative) phase,May precipitation would be more(less).From January to April,meridional wave structure appeared over the Pacific,the wave was basically consistent from low level to high level in troposphere and changed with the time,the Pacific region would be another influencing key area for May precipitation of Yunnan.