Standardized Climate Indices (SCI)

The SCI package is a free extension to the R language that efficiently calculates Standardized Climate Indices, including the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), and the Standardized Runoff Index (SRI). The SCI package adds flexibility by incorporating a free choice of the statistical distribution used for data transformation, maximum likelihood estimation, and use of reference periods.

User guide (pdf)

SCI package (CRAN archive)