4552035152

ZOFIA KACZOROWSKA

PRECIPITATION IN POLAND IN LONG-PERIOD AVERAGES

Summary

In the first part of this paper, the author investigates the trend of pre-cipitation, its tendencies and its plus and minus sign. She smoothes the se-ries of the sums of precipitation by the method of least sąuares, assuming a straight-line correlation to exist between time and yearly amounts of precipitation.

During the period from establishing climatic stations (1813—1878) until 1958, among the 12 investigated stations three situated in Central Poland

disclose a slight tendency of decrease (—0.1--0.9 mm/year), whereas nine

stations situated in the Northern, Western and Southern part of the country showed a tendency of increase (0.3—0.6 mm/year).

Verification of the validity of these results revealed the interdependence between time and total precipitation to be essential at 5 stations only, all of them showing a tendency of increase, — presupposing a confidence level eąualling 0.1 (Fig. 1).

In order to tie up with investigations madę by W. Okołowicz [22], J. Ostromęcki [25] and J. Lambor [17], the author additionally analyzed the series of total precipitaton for the 1851—1958 period. Among 8 investi-gated stations, 7 maintained a tendency of increase and 1 of decrease, whereof only 4 proved the validity of this determination (Fig. 2).

In order to illustrate the changes in the character of precipitation tendency during the recent 20-year period, the author investigated in closer detail the period from 1900 to 1959 on the basis of obseivations of 16 full-period stations and 28 stations with a „reduced“ period of observations (1900—1902, 1904—1913, 1918—1937, 1946—1959 (Fig. 4).

During the fuli period, a tendency of increase was maintained solely in the Eastern part of the country, whereas the whole West, Centre and South shows a tendency of decrease. The validity of correlation proved very feeble, and has been established for 4 stations only (Fig. 3).

During the „reduced“ period of observations there occurred in Northwestern, Western and Southern Poland a tendency of decrease (—0.2 —