2.5.2. Measurement of Variability

The Standardized Anomaly Index (*SAI*) was calculated to discern variation in average temperature across the years. It was calculated using the following formula:

$$SAI = \frac{T\_A - T\_M}{\delta}$$

where *TA* refers to average temperature of a year; *TM* shows long-term (1988–2017) mean average temperature; and δ is standard deviation of the long-term average temperature. The annual Rainfall Anomaly Index (*RAI*) was used to identify years and seasons of positive and negative anomalies [32]. It was computed as follows for positive and negative anomalies, respectively:

$$RAI = \ +3\left(\frac{RF - M\_{RF}}{M\_{H10} - M\_{RF}}\right) \text{ and } \ RAI = \ -3\left(\frac{RF - M\_{RF}}{M\_{L10} - M\_{RF}}\right)$$

where *RF* is the amount of rainfall during a particular year; *MRF* is the mean rainfall of the observation period (1988–2017); *MH*<sup>10</sup> is mean rainfall of the 10 highest values during the observation period; and *ML*<sup>10</sup> is the mean of the lowest 10 values of the period of record.
