Okresy suche i wilgotne w Łodzi w XX wieku

Abstract

The aim of this work is to present the results of total daily precipitation series, which had been registered in Łódź in 1904-2000. In the structure of daily precipitation conditions the days without falls (54.2%) and with falls of 0.1-4.9 mm (36.1%) were dominant. Total maximum daily precipitation changed perennially from 14.2 mm to 103.5 mm. The longest continuous peńods of dryness in Łódź lasted 45 days, whereas the longest periods of continuous falling lasted 31 days. It was observed that 40's and 50's were the years of the most frequent dry periods. Maximum length of continuous precipitation periods shortened from 30 days in 30's to 14 and 15 days in 80's and 90's. Looking for long lasting tendencies of the time changeability of precipitation characteristics by using non-parametric test by Mann-Kendall and non-parametric Sen's method, which is used for calculating regression coefficients in linear trends equations, shows lack of statistically significant tendencies. This happens in case of daily capacities and extreme total fall, as well as total annual number of days without and with falling being equal or bigger than 5 mm and ~ 10 mm. Positive trends, statistically significant on a level of 0.05 characterize dryness indices in February and April, while indices on a 0.01 level are characteristic for August.