Possible Causes for the Anomalous Weak East Asian Winter Monsoon in 2013/2014
The East Asian winter monsoon was stronger than normal continuously for seven years since 2005,but it suddenly shifted to be weaker than normal in winter 2013/2014.The research results indicated that the increased Arctic sea ice extent in the last autumn was responsible for the negative sea level pres-sure in Siberia in winter 2013/2014,resulting in the weakening of Siberian high which was favorable for the anomalous weak East Asian winter monsoon and high temperature in China.During the winter,East Asian winter monsoon exhibited strong intraseasonal variations,weaker in the early winter and stronger in the late winter.Accompanying the intraseasonal variations of the East Asian winter monsoon,the temper-ature over China had two-stage variations in the last winter,warmer in the early winter and colder in the late winter.Furthermore,the warmer in the early winter and colder in the late winter over China also was influenced by the blocking high activities over the North Pacific.In the late winter,the westward shifting of the blocking high to the west of date line strengthened the merional circulation over East Asia,leading the sweeping down of the cold air over East Asia,further causing the anomalous low temperature in China in the late winter.However,the westward shift of the blocking high over the North Pacific may be related to the stratospheric circulation anomalies.
East Asian winter monsoonArctic sea iceblocking high
国家科技期刊平台
NSTL
万方数据
维普
