Impact of moisture source variation on decadal-scale changes of precipitation in North China from 1951 to 2010

The Hybrid Single-Particle Lagrangian Integrated Trajectory platform is employed in this study to simulate trajectories of air parcels in the rainy season in North China during last six decades (1951–2010), with the purpose of investigating moisture sources, their variation, and the eventual relationship with precipitation in North China. Climatological trajectories indicate that moisture in North China originates, respectively, from Eurasia (14.4%), eastern China (10.2%), the Bay of Bengal-South China Sea (33.8%), the Indian Ocean (10.7%), and the Pacific (30.9%). The spatiotemporal analysis of moisture trajectory based on extended empirical orthogonal function indicates that a decrease of precipitation in North China is caused mainly by a decrease of water vapor sources from the south, the Indian Ocean, the Bay of Bengal, and the South China Sea, which overwhelms an increase of water vapor sources from the North, mainly Eurasia, eastern China, and northern western North Pacific Ocean. In particular, the significant decrease of precipitation in the late 1970s (by 11.6%) is mainly caused by a 10.6% decrease of moisture from all sources. The Bay of Bengal, the South China Sea, and the Indian Ocean are dominant moisture source areas affecting the decadal-scale variation of precipitation in North China.