Figure 1

(a) Topographic features and hydrological networks in arid eastern–central Asia (AECA). Major rivers in the Chinese portion of AECA are drawn in blue. Glaciers are drawn in white. Solid dots denote weather stations, with cyan stations located in the Tien Shan, brown stations located in basin areas, and grey stations located in other parts of AECA. River runoff measurement stations are indicated with numbers corresponding to the key in Fig. 4. The subregions of AECA discussed in the text are delineated by the cyan dashed line (Tien Shan) and the brown dashed line (basin areas). Time series of standardized warm season precipitation anomalies based on station records (black) and an ensemble of six gridded precipitation datasets (blue) in (b) AECA (all dots in a), (c) the Tien Shan mountains (cyan dots in a), and (d) basin areas (brown dots in a). All data are normalized relative to the mean and standard deviation of the overlapping period (1998–2007) prior to construction of the ensemble. Climate shifts in the time series are marked in red, including changes in the mean state over all AECA and the basin areas in 1987 and a change in the trend over the Tien Shan mountains in 1998 (see Methods for details). Shading and dotted lines in (b–d) indicate 95% confidence intervals.