A Study of the Circulation Patterns Affecting Drought and Wet Years in Central Iran

Table 1

Varying intensities of drought based on standard precipitation index.

Standard precipitation index	Index value
2 and more	Strongly severe wet years
1.5 to 1.99	Severe wet years
1 to 1.49	Moderate wet years
to 0.99	Normal
−1 to −1.49	Moderate drought
to	Severe drought
and less	Strongly severe drought