Fig. 1: The monsoon region and its north-south division in China.
From: Divergent impacts of climate interventions on China’s north-south water divide
a Topography and climate zones; b Precipitation climatology; c Temperature climatology; d The first Empirical Orthogonal Function (EOF) mode of precipitation (1901–2020) over China. Topography data is from the Copernicus Global Digital Elevation Model96. Precipitation climatology and temperature climatology is based on observations from 1960 to 2021 in China97. The EOF in d was calculated based on data from the Climate Research Unit (CRU ts4.06). The monsoon region encompasses major river basins in Eastern China (east of the black line), based on GIS Dataset of Boundaries among four Geo-Eco Regions of China98. The Qinling mountain range-Huaihe river (blue line, around 33°N) in the monsoon region is typically regarded as the dividing line between northern and southern China, with the south being wetter and the north being drier in terms of annual precipitation (b)99. The climatic boundary (red line, around 41°N) between the warm temperate zone and the mid-temperate zone (c)100 further divides the monsoon region to northern and northeastern regions. The dashed ellipses in d characterize the well-known North-Drought (pink ellipse) South-Flood (cyan ellipse) hydrological division (NDSF) of China60,101,102. This study focuses on the relatively drier northern monsoon (between red and blue lines) and wetter southern monsoon (south of blue line) regions, largely consistent with NDSF regions, to analyze climate intervention impacts on NDSF.
