Dynamic Plateau Monsoon Index and its Association with General Circulation Anomaly
Based on monthly ECMWF re-analysis-Interim (ERA-Interim) reanalysis data and monthly precipitation and temperature data,a Dynamic Plateau Monsoon Index (DPMI) was defined; it is a revision of the Traditional Plateau Monsoon Index (TPMI).A contrast analysis of the DPMI versus the TPMI was then conducted.The general circulation response to northern Qinghai-Xizang plateau summer monsoon anomalies and the correlation of the DPMI with general circulation anomalies were investigated.The results of this study show that during the plateau summer monsoon,the main body of the plateau is controlled by a powerful warm low; the wind field makes a cyclonic meander near the surface; and the air flow over the plateau converges toward the changeable warm low center over time.The DPMI reflected meteorological elements better and depicted climate variation more accurately than did the TPMI.In years when the plateau summer monsoon is strong,the low over the plateau and the trough near the eastern coast of Asia are deeper and higher than normal over South China.This correlation corresponds to two anomalous cyclones over the plateau and the eastern coast of Asia and an anomalous anticyclone in South China.The plateau and its adjacent regions are affected by anomalous southwesterly winds that transport more moisture to South China and cause more precipitation.The lower reaches of the Yangtze River appear to receive more precipitation by means of the strong westerly water vapor flow transported from the “large triangle affecting the region,” which corresponds to the strong plateau summer monsoon.In years when the plateau summer monsoon is weak,the low over the plateau and the trough near the eastern coast of Asia are shallower,and 3 the high over South China is weaker than normal,which corresponds to two anomalous anticyclones over the plateau and the eastern coast of Asia and an anomalous cyclone in South China.The plateau and its adjacent regions are affected by anomalous northwesterly winds that transport less moisture to South China and cause less precipitation,the lower reaches of the Yangtze River receive less precipitation due to the weak westerly water vapor flow transported from the “large Triangle affecting region,” which corresponds to the weak plateau summer monsoon.The plateau monsoon is closely related to the intensity and position of the South Asian high,and the existence of a teleconnection pattern in the mid-upper levels suggests a possible linkage of the East Asian monsoon and the Indian monsoon to the plateau summer monsoon.
Qinghai-Xizang Plateau Dynamic Plateau Monsoon Index low pressure systems center position general circulation
荀学义 胡泽勇 马耀明
国内会议
沈阳
英文
1-42
2012-09-01（万方平台首次上网日期，不代表论文的发表时间）