Figure 4 Spatial distribution of precipitation estimation parameters α , βfor 698 weather stations in China
As shown in Figure 4 . the gamma distribution is used to well fit the estimated parameters α and β of PDC for 698 weather stations across China. The values of α , except for the stations in the southwest and southeast inland regions of China distributed above 0.6, is basically distributed between 0.2 and 0.6. From Figure 4 (b), it can be found an increasing trend ofβ from northwest to southeast of China, and β is mainly distributed between 0 and 10 in northwest China, and is mainly distributed between 10-20 at stations in Northeast China, Central China, and Yunnan Province, and is distributed between 20-30 in most areas in the southeast, with a small number of coastal cities in the southeast distributed between 30 and 70. From the figure, it is discovered thatβ shares a similar spatial distribution pattern with average annual precipitation in China.