Long-term changes in observed temperature and precipitation series 1901-1998 from Hungary and their relations to larger scale changes

Trends and low frequency fluctuations relying on 14 observed temperature and precipitation series 1901-1998 from Hungarian sites are presented. The statistical significances of systematic changes are calculated by the t-test for the linear trends and the Mann-Kendall test. Characteristics of long-term fluctuations are investigated by spectrum analysis (Fisher-test), fitting optimum-ranked polynomials as well as illustrated by smoothed curves of 15-point Gauss-filter application. While the increase of mean temperature in Hungary during the 20(th) century is not significant, the annual precipitation totals have substantially decreased. In the first half of the century mainly the precipitation totals in the transitional seasons decreased. By the second half of the century the seasonal structure of the precipitation trends has altered significantly: there was practically no systematic change in the transitional seasons, but winter precipitation decreased dramatically. The paper makes some comparisons with the same type climatic characteristics of the surrounding geographical regions, the temperature changes of the Northern Hemisphere, as well as discusses the relationship between winter precipitation in Hungary and the North Atlantic oscillation. A significant 50-year oscillation was found in the summer mean temperatures and the annual sums of extreme positive daily temperature anomalies in Hungary. This oscillation seems to be in tune with other processes over the Euro-Atlantic region. A cycle of 3.6 years in the annual precipitation totals was found to be significant at the 0.10 level.