Changes in Precipitation in Poland in the 21^st Century in the Light of Quantile Classification

Abstract

The study aims to analyze the variability of the precipitation character of seasons and years at selected stations in Poland in the 21st century. The work includes six meteorological stations located in specific regions of Poland. The precipitation character of years and climatic seasons was determined using quantile classification, based on the values of 10, 30, 70, and 90% quantile of the empirical distribution of seasonal and annual precipitation. 1971-2010 precipitation data (normal period) were applied to calculate the quantiles values. In spring (MAM), the highest frequency of precipitation anomalies was recorded in Wroclaw station. In the 21st century, precipitation of only one spring period was classified as normal at this station. Seven springs were dry or very dry, and 11 were wet or very wet. The most stable seasonal precipitation in spring was observed in Suwałki station. In the years 2001-2019, the twelve spring seasons had normal rainfall. Three spring seasons in Suwałki were classified as dry or very dry and five as wet or very wet. In the summer season (JJA) Szczecin and Wroclaw recorded a high frequency of precipitation anomalies. At each of these stations, 15 summer seasons were characterized by abnormal rainfall. The frequency of rainfall anomalies in the summer season was the smallest in Suwałki, where ten seasons with abnormal rainfalls were recorded, including three seasons with low or very low rainfall and six seasons with high or very high rainfall. In the autumn season (SON), precipitation was more stable in western and central Poland, where the number of seasons with abnormal precipitation ranged between 9 in Szczecin and Wroclaw to 10 in Lodz. In Lublin, on the other hand, as many as 15 seasons with abnormal rainfall was recorded in the 21st century. In the winter season of 2001-2019, rainfall amounts of unusual nature dominated at all stations, with the frequency being higher at these located in eastern Poland. The analysis of annual sums of precipitation showed that most years were abnormal in terms of precipitation, with a higher frequency of precipitation anomalies at stations located in the eastern part of the country.