Exploration of Use of Copulas in Analysing the Relationship between Precipitation and Meteorological Drought in Beijing, China

Table 1

Classification of SPEI values.

Class	SPEI value	Description
1	SPEI ≥ 2.00	Extremely wet
2	1.50 ≤ SPEI < 2.00	Very wet
3	1.00 ≤ SPEI < 1.50	Moderately wet
4	−1.00 ≤ SPEI < 1.00	Near normal
5	−1.50 ≤ SPEI < −1.00	Moderate drought
6	−2.00 ≤ SPEI < −1.50	Severe drought
7	SPEI < −2.00	Extreme drought