Variability of sequences of days with precipitation in the eastern part of the Mazowian Lowland

Abstract

This study aimed to examine the frequency and variability of sequences of days with atmospheric precipitation across the Mazovian Lowland during the growing season (April–October) over the period 1971–2020. The research was based on daily precipitation totals recorded at meteorological stations in Legionowo, Pułtusk, and Siedlce. A precipitation sequence was defined as a series of consecutive days with rainfall ≥0.1 mm, and classification was conducted following the methodology proposed by Zawora (1995). The structure and variability of these sequences were assessed in both spatial and temporal dimensions, and trends in their number were analysed using the Mann– Kendall test. During the study period, a total of 1,787 precipitation events at least three days long were recorded. The majority (approximately 64%) comprised sequences of 4–9 days. Shorter, 3-day events represented 19% of observations, while sequences exceeding 9 days were considerably less frequent. Exceptionally long sequences (≥23 days) occurred sporadically. The highest number of short and medium-length events was observed in Legionowo, whereas Siedlce experienced a greater frequency of extended sequences exceeding 10 days. The structure of sequences in Pułtusk was the most stable, with a predominance of medium-length series. Seasonally, 4–9 day sequences were most common in spring, while in the latter half of the growing season, both short events and those exceeding 10 days became increasingly prominent.