Inter-decadal Relationships between Summer Arctic Oscillation and Aridity-Wetness Feature in Northwest China
夏季北极涛动与西北夏季干湿特征的年代际关系

Based on observation data of summer precipitation and evaporation from 1960 to 2003 at 131 stations in Northwest China(Xingjiang,Qinghai,Gansu,Ningxia,Shanxi and the west of Neimenggu) and summer Arctic Oscillation index,at first,an aridity-wetness homogenized index was defined,then the correlation between summer Arctic Oscillation and summer drought and moist characteristics of northwest China was analyzed.The results show that the inter-decadal correlation is prominent between summer Arctic Oscillation and summer drought and moist characteristics of northwest China.In decades with strong summer Arctic Oscillation,the sea level pressure(SLP) was positive anomaly in East Asia and negative anomaly in Pacific;700 hPa wind field showed anticyclone anomaly circumfluence in Baikal and its south region,west wind anomaly in westerly region of Northwest China and north wind anomaly in monsoon region of Northwest China;500 hPa height field showed west-low and east-high characteristics in Northwest China,thus the East Asia monsoon was weakened,the west wind air flow prevailed in westerly wind region of Northwest China,precipitation increased and the climate became wetter,while north wind air flow prevailed in monsoon region of Northwest China,precipitation decreased and the climate became more dry,and vice versa.