Circulation types and their relationships with extreme wind energy generation events in Poland

This study investigates the influence of different atmospheric circulation types on wind energy production in Poland from 1948 to 2019. By utilizing the ERA5 reanalysis dataset, which provides detailed atmospheric and surface parameters, and the Litynski calendar of circulation types, this research is directed toward understanding how various circulation patterns affect wind energy generation. The study specifically focuses on periods of energy droughts (days with very low wind energy production) and energy floods (days with very high wind energy production). The analysis reveals trends, along with annual and seasonal variations in the frequency of energy droughts and floods. Over the period of study, the number of drought days varied from 51 to 108 per year, while the number of flood days varied from 44 to 97 per year. Cyclonic circulation types with NW winds are found to be the most favorable for wind energy production, leading to higher daily energy generation. Conversely, anticyclonic circulation types with winds from the north, northeast, and east are more likely to result in energy droughts. Certain seasons exhibit higher variability in the number of drought and flood days, influenced by the prevailing circulation types. The standard deviation of the number of drought days in summer is 7.3 compared to 4.8 in spring; for flood days the standard deviation for winter is 8.4 and for summer only 3.4.