Moisture conditions during the vegetation season in years 1954–1995 in Łódź

The standardized precipitation index (SPI), standardized reference evapotranspiration index (SEI) and standardized climatic water balance index (SCWBI) were used to analyze moisture conditions in the vegetation seasons of 1954–1995 in Łódź. SPI and SEI were calculated on the assumption that empirical monthly precipitation sums and monthly sums of reference evapotraspiration are gamma distributed. Because monthly sums of climatic water balance are normally distributed, they required standardization to SCWBI. The aim of study was to compare those three indexes (SPI SEI and SCWBI) for years 1954–1995 in Łódź.