The relationship between the state of the stratosphere and the occurrence of meteorological drought in Poland
Meteorological drought has a strong impact on many areas of life. In this paper, this phenomenon is of interest during the warm and cold halves of the year at 11 synoptic stations in Poland. The five classes of drought are specified by the value of the standardized precipitation index (SPI). This article attempts to verify the hypothesis of the connection between the class of drought and changes in the stratosphere. The state of the stratosphere is defined based on temperature, geopotential height, and the zonal wind component at levels from 10 hPa to 250 hPa. A selection of potential predictors is proposed based on the correlation. The information capacity for the full set of predictors is compared with the capacity given by the selected explaining variables. The self-organizing map (SOMs) method was used to determine the input stratospheric patterns for each drought class. Then, using a fuzzy classification, drought classes were reconstructed based on pre-defined patterns. Next, the verification of the quality of the model for the connection stratospheredrought for various configurations was conducted, indicating the best model parametrisation. The results are promising. However, it is crucial that the validation be carried out separately for each synoptic station and updated with the addition of extra data.