INTERANNUAL VARIATION OF EAST ASIAN WINTER MONSOON IN EARLY AND LATE WINTER AND ITS RELATIONSHIP WITH EAST ASIAN PRECIPITATION

JIAN Yun-tao; JIAN Mao-qiu; YANG Song

doi:10.16032/j.issn.1004-4965.2017.04.009

Abstract：Based on the ERA-Interim reanalysis data and the NOAA sea surface temperature (SST) and CMAP precipitation data,the interannual variability of the East Asian winter monsoon (EAWM) in early and late winter and itsrelationshipwith the precipitation over East Asia are studied in this paper.The relative importance of tropical and mid-high latitude circulation systems for the variability of EAWM is also discussed.The first leading mode of anomalous early EAWM shows significant anomalies in the whole East Asia,meaning that strong or weak northerlies occur in the whole East Asia consistently.The second leading mode is a southern anomalous pattern with strong or weak northeasterlies over southern China and the northern South China Sea.From early winter to late winter,these first two leading modes of the EAWM appear alternatively.Although the leading modes of the early and late winter EAWMs exhibit large interannual variability,there exists an intensified trend of the monsoon in the first leading mode.The locations of large precipitation anomalies associated with the leading anomalous patterns of EAWM are different.In early winter,the variation of EAWM mainly influences the precipitation over northern China,the Bohai Sea,the Yellow Sea,the Korean Peninsula,and southern Japan.In late winter,however,the EAWM is linked to the precipitation anomalies over Southeast China and its eastern vicinity.Both tropical Indo-Pacific SST and mid-high latitude circulation systems affect the first two leading modes of the early winter EAWM significantly,but ENSO and mid-high latitude circulation systems play important roles on the first and second modes of the late winter EAWM,respectively.