极端干旱

中等干旱

轻度干旱

正常

轻度湿润

中等湿润

极端湿润

SPEI-3

£−2.0

−2.0~−1.0

−1.0~−0.5

−0.5~0.5

0.5~1.0

1.0~2.0

³2.0