Changes in the amount of low clouds in Estonia (1955-1995)

Based on data from 16 meteorological stations, trends in the amount of low clouds in Estonia have been investigated for the period 1955-1995. Analysis shows that the amount of low clouds has increased in March at all stations, in June at 12 stations and in September at eight stations. The amount of low clouds has decreased in May at seven stations and in October at five stations. Only trends that are significant at at least the 0.1 level were taken into account. Regression analysis shows that the increase in the amount of low clouds in March can be ascribed to changes in the frequencies of occurrence of European circulation patterns and/or to an increase in the amount of low clouds within the zonal circulation. Copyright (C) 2001 Royal Meteorological Society.