Progress in Research on the East Asian Monsoon

Chinese Academy of Meteorological Sciences (CAMS) has organized the investigation on the East Asian Monsoon with its influences on the weather and drought/flood in China for a long term since the foundation of new China. A summary of the achievements of the past researches by CAMS is briefly depicted. A basic review of the East Asian Monsoon researches in China after 1950s; the study on the East Asian Monsoon circulation system (EAMCS): the history of proposals to EAMCS affecting the weather and climate in China, the interactions between East Asian and Indian Monsoon system, the water vapour transportation resulting in the torrential rain in China, and the design of the monsoon index representing the East Asian Monsonn activity are set forth. The seasonal variation of EAMCS is summarized on the onset of the South China Sea Summer Monsoon, Meiyu and the rainy season in China and its propagation. The Madden-Julian oscillation (MJO) of EAMCS and its impacts on the summer precipitation in China are presented by the study on the characteristics of zonal and meridional propagation of the subtropical MJO of EAMCS, the differences between it and that on the Equatorial area, and its possible effects on the formation of El Niño, the onset of East Asian tropical and subtropical monsoon and the weather and climate in China. The calculation and distribution of atmosphere apparent heat source in Asia, and its possible influence on the East Asian Summer Monsoon and the rainfall, and the possible influence of the winter cold source over the Tibetan Plateau on the formation of El Niño are given. The inter-annual and interdecadal variation of the EAMCS are reviewed on the characteristics of the inter-annual variation of the EAMCS and the rainfall, the analysis of the quasi-4-year oscillation, the interaction between it and the formation of El Niño, the impact of the polar region on the summer rainfall in East Asia, and the inter-decadal variation of the EAMCS. The possible mechanism of the formation of the EAMCS is proposed, especially the essential role in the formation of summer and winter monsoon, the EAMCS and the Indian Monsson system of the land-sea thermal difference between the Asian continent and the West Pacific, the African continent, the Indian and IndoChina peninsula, Australian continent, and the ocean and sea around them.