Spatiotemporal Variations of Drought in the Arid Region of Northwestern China during 1950–2012

Table 3

Frequency of droughts in each season (%).

Season	SPI	SPEI	SC-PDSI	Average drought frequency
Spr.	13.89	19.44	36.11	23.15
Sum.	18.89	22.78	44.44	28.70
Fall.	21.11	25.56	38.33	28.33
Win.	18.89	28.33	36.11	27.78