Moisture Sources and Their Contributions to Summer Precipitation in the East of Southwest China |
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Authors: | LI Yong-hu HUANG Ding-an LU Chu-han XIANG Bo ZHOU Jie and HE Juan-xiong |
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Institution: | 1. CMA Key Open Laboratory of Transforming Climate Resources to Economy/Chongqing Climate Center, Chongqing 401147 China,2. School of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing 210044 China,3. Key Laboratory of Ecosystem Carbon Source and Sink, China Meteorological Administration (ECSS-CMA), Wuxi University, Wuxi, Jiangsu 214063 China,1. CMA Key Open Laboratory of Transforming Climate Resources to Economy/Chongqing Climate Center, Chongqing 401147 China,1. CMA Key Open Laboratory of Transforming Climate Resources to Economy/Chongqing Climate Center, Chongqing 401147 China and 4. CAS-TWAS Center of Excellence for Climate and Environment Sciences, Beijing 100029 China |
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Abstract: | Complex topography, special geographical location and sea-land-air interactions lead to high interannual variability of summer precipitation in the east of Southwest China (ESWC). However, the contributions, influencing factors and mechanisms of remote and local evaporation remain to be further investigated. Using clustering analysis and Hybrid Single-Particle Lagrangian Integrated Trajectory version 5 model, we analyze the contributions of remote moisture transport and local evaporation to summer precipitation in the ESWC and their causes. There are mainly five remote moisture channels in the ESWC, namely the Arabian Sea channel, Bay of Bengal channel, western Pacific channel, Northwest channel 1 and Northwest channel 2. Among the five channels, the western Pacific channel has the largest number of trajectories, while the Bay of Bengal channel has the largest contribution rate of specific humidity (33.33%) and moisture flux (33.14%). The amount of regional average precipitation is close to that of the precipitation caused by remote moisture transport, and both are considerably greater than the rainfall amount caused by local evaporation. However, on interannual time scales, precipitation recirculation rates are negatively correlated to regional average precipitation and precipitation caused by remote moisture transport but are consistent with that caused by local evaporation. An apparent "+ - +" wave train can be found on the height anomaly field in East Asia, and the sea surface temperature anomalies are positive in the equatorial Middle-East Pacific, the South China Sea, the Bay of Bengal and the Arabian Sea. These phenomena cause southwest-northeast moisture transport with strong updrafts, thereby resulting in more precipitation in the ESWC. |
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Keywords: | east of Southwest China summer precipitation moisture sources local evaporation contributions of moisture |
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