Drought indices for the Czech Republic (1876–2018)

Drought indices were calculated for 8 long-term stations located in the Czech Republic, their elevations ranging roughly from 200 to 450 m a.s.l. The sites represent weather stations with the longest daily precipitation and temperature records available within the Czech Hydrometeorological Institute database. The study applies four drought indices. Palmer Drought Severity Index (PDSI; Palmer, 1965) was one of the first historical attempts to identify droughts using more than just precipitation data. This index incorporates precipitation, temperature, and water-holding capacity of soils. Although it originally was developed to identify droughts affecting agriculture, PDSI is used today also for other applications. Palmer Z Index (PZIN) is a first step in estimating PDSI and it expresses anomaly in water balance over the calculation period. It therefore responds to short-term conditions better than does PDSI and enables identifying rapidly developing drought conditions. Another drought index applied is the Standardized Precipitation Evaporation Index (SPEI) that uses precipitation and temperature data only. Two versions of SPEI were calculated: SPEI-52, which characterizes rather long-term droughts, and SPEI-4, which is more suitable for analyzing short-term events. All drought indices were calculated using temperature and precipitation data only, because other drought-related meteorological variables (e.g., solar radiation, wind speed, and humidity) are not available in these historical records. The indices are available in weekly temporal resolution (52 values per year) from the start of the individual stations’ observation to 2018. The longest records are available for Prague-Klementinum and Tabor (1876–2018, 143 years) while the shortest series at Klatovy starts in 1922 (97 years).