Features of the precipitation changesover the Svalbard in the annual cycle

Abstract

This article discusses the changes in an annual cycle of precipitation observed over many years in the Svalbard area. Monthly precipitation sums recorded at the Isfjord Radio station, Björnöya, Jan Mayen were used to accomplish the analysis. Data presented come from GHCN (Vose et al. 1997), MCDW (1957-1997) and WWR (1929,1944,1947,1959,1968,1979,1981, 1987, 1994, 19(5). The characteristics of the annual precipitation were described using Wilgat's indicator of periodicity of precipitation ( 1949) and Vemic's pluviometric coefficient (Szreffel 1961). Apart from that the amount of the highest and the lowest occurrence of precipitation in each month was calculated during the 10-years moving periods. In addition the annual change of the monthly sums of precipitation was characterised. The analysis of the annual change of the periodicity indicator has proved that during the examined period the precipitation regime on Isfjord Radio station and Jan Mayen do not show clear changes. On Björnöya station from the mid forties periodicity of precipitation has decreased. On all examined stations until the late thirties the value of the pluviometric coefficient were less than 50%. Since the mid forties over half of the amount of precipitation occurred from March to November. The highest sums of precipitation most often occurred in April, May and June. The highest sums of precipitation on Jan Mayen station and Björnöya station occurred mainly in September and October. On Isford Radio station the highest sums of precipitation were recorded chiefly in March. September. February and August