Mechanism of the summer rainfall variation in Transitional Climate Zone in East Asia from the perspective of moisture supply during 1979–2010 based on the Lagrangian method

Transitional Climate Zone (TCZ) over East Asia, characterized by semi-arid climate, is ecologically fragile environment with limited water resources, making atmospheric moisture supply being the key influential factor. This study investigates sources of summer (JJA) rainfall in TCZ Asia and associated impact during 1979–2010 Lagrangian particle dispersion model. Seven source regions contribution are quantified: Eurasia continent to northwest (EC, 32.14%), central-eastern China (CEC, 16.62%), western Pacific Ocean (WPO, 8.58%), South Sea Indonesia (SCSI, 2.99%), Bay Bengal (BOB, 1.4%), Arabian (AS, 0.71%) local evaporation (TCZ, 32.58%). The direct from ocean (13.67%) much less than those (81.34%), due great loss en-route. In particular, not only contributes most among 7 selected regions, but also exerts greatest influence precipitation variability TCZ. Furthermore, related conveyed westerlies monsoon discriminated according dominant system regions. It found that contributions (30.3%) mid-latitude (32.14%) areas quite close. However, further analysis shows takes more responsibility for inter-annual fluctuation perspective supply, followed westerlies.