Contrasting impacts of spring thermal conditions over Tibetan Plateau on late-spring to early-summer precipitation in southeast China

Abstract

The thermal condition of the Tibetan Plateau (TP) is considered as an important factor impacting the Asian monsoon. However, how to determine the thermal condition and when and where the Asian monsoon is influenced are still open issues. Here the spring thermal condition of TP is determined using 600 hPa temperatures. For the past 30 years (1979-2008), we have determined three cold years (CY) and three warm years (WY) and conducted contrasting analyses of the subsequent precipitation and large-scale atmospheric dynamics over China. Our analyses indicate that the precipitation is more than normal in late spring (LS) and less than normal in early summer (ES) during WY in southeast China (SEC), while the opposite pattern is true during CY. Further analyses of 850 hPa circulation and tropospheric vertical motion show that the anomalous southerly wind and ascending motion are dominated in SEC during LS for WY and ES for CY, while the anomalous westerly wind and descending motion are dominated during ES for WY and LS for CY. The coherent dynamical structure impacts the monsoon moisture transport and large-scale atmospheric stability, and therefore is the fundamental cause of precipitation anomalies. © 2011 Royal Meteorological Society © 2011 Royal Meteorological Society.