Climate indicators: standardized precipitation evapotranspiration index (spei)

Other: Standardized Precipitation Evapotranspiration Index: A precipitation and evapotranspiration(Hargreaves) anomaly is considered relativ to the mean of a reference period (1981-2010) and based on the underlying statistical distribution (Gamma). The anomlies are considered over different months (3, 6, 9, 12). (More information under: https://climate-indices.readthedocs.io/en/latest/)