The cyclical nature of seasonal precipitation in Pomerania in the period 1951-2010

Abstract

The aim of the present paper is to detect recurring fluctuations in the course of annual and seasonal total precipitation in Pomerania. The basic material consisted of monthly sums of atmospheric precipitation obtained from 11 IMGW weather stations from 1951-2010. The analysis comprised both annual and seasonal precipitation recorded in spring (March-May), summer (June-August), autumn (September-November), and winter (December-February). The results of spectral analysis obtained using module functional series revealed a significant cyclical nature of rainfall occurrence. Annual and seasonal total precipitation recorded at 11 stations representative for Pomerania that occurred in the period 1951-2010, have cycles of variable length, i.e., 10-year period for annual sums, 30-year period for autumn, and quasi 7-year period for winter sums. However, the detected cyclical elements differed depending on the station, and their lengths varied greatly depending on the season: approximately from 6 to 30 years. The greatest variability in cyclicality was recorded in summer precipitation, whereas during the calendar spring the changes in total precipitation recorded at most of the hstations in periods of the same length.