Drought indices constructed for the area of Poland are based on:
instrumental data (eight long-term precipitation series) for period 1722-2015. The delimitation of droughts was conducted using two independent approaches. In the first approach (see file: Standard Precipitation Indices (SPIs)) the globally and nationally popular Standard Precipitation Index (SPI) calculated for 1-, 3-, and 24-month timescales was used. Three categories of droughts were analysed: meteorological (SPI1), agricultural (SPI3) and hydrological (SPI24). For delimitation of droughts (dry months), the criteria used were those proposed by McKee (1993) and modified for the climate conditions of Poland by Łabędzki (2007). Droughts were divided into three categories based on the following SPI values: moderate droughts (-0.50 to -1.49), severe (-1.50 to -1.99), and extreme (≤ -2.00). The second approach (see file: Droughts in Poland. Instrumental data) includes the new proposed method for distinguishing droughts and quantitatively estimating their intensity and duration. The following criteria were adopted to identify droughts and determine their duration. Firstly, instances of an SPI1 value within any of the above ranges for only a single month were considered irrelevant. Secondly, a drought was considered to be at least two consecutive months during which the SPI1 value was below -0.50. Thus identified, a drought was determined both in terms of duration and by category. Thirdly, drought category was determined by the dry month of lowest SPI1 value. A drought was thus considered extreme if the SPI1 value for at least one of the drought months was ≤ -2.00. If the SPI1 of the driest month within a particular instance of drought was between -1.50 and -1.99, the drought was determined to be severe. The remaining droughts were qualified as moderate. Number of droughts was determined for years and for climatological seasons. A drought’s final month determined its season.
various documentary sources from period 1451–1800; intensity, spatial coverage, and duration were taken into account (see file: Droughts in Poland. Historical data). The dataset is constantly updated and please contact us if you want the latest version.
References:
Łabędzki, L., 2007, Estimation of local drought frequency in Central Poland using the standardized precipitation index SPI, Irrig. Drain., 56, 67–77.
McKee, T. B., Doesken, N. J., and Kleist, J., 1993, The relationship of drought frequency and duration to time scales, in: Proceedings of the 8th Conference on Applied Climatology, Anaheim, 17–22 January 1993, 17, 179–183.
Related publication to cite using this dataset:
Przybylak R., Oliński P., Koprowski M., Filipiak J., Pospieszyńska A., Chorążyczewski W., Puchałka R., Dąbrowski H. P. 2020. Droughts in the area of Poland in recent centuries in the light of multi-proxy data. Clim. Past. 16: 627–661, https://doi.org/10.5194/cp-16-627-2020