资源环境科技发展态势分析平台

Daily precipitation data from 162 stations in the Czech Republic over 1961-2012 are used to examine changes in seasonal precipitation indices, their spatial patterns and links to temperature and atmospheric circulation. The results show a divide between the western and eastern parts of the country as to trends in most precipitation characteristics in both winter and summer. Increases were more pronounced in the west, where Atlantic influences are stronger. In the eastern region, where continental and Mediterranean influences become more important, the trends are often inconclusive. Aggregated over the country as a whole, positive trends of mean precipitation as well as indices of precipitation intensity and extremes dominate in both winter and summer, and the mean precipitation trends are significant at a much larger percentage of stations than previously reported for 1961-2005. Spring is the only season with prevailing negative trends in mean precipitation and the number of wet days. The trends are least conclusive and close to zero in autumn. The trends differ for cold days (below the seasonal 25th percentile of daily maximum temperature) and warm days (above the seasonal 75th percentile). In contrast to overall winter trends, negative trends of mean precipitation, seasonal maxima and number of wet days prevail on cold days in winter. In summer, by far the most pronounced positive trends occur during warm days, when most precipitation comes from convective storms. Longitudinal dependency was found for most indices in winter and for mean precipitation and the number of wet days in summer. The different influence of the North Atlantic Oscillation on precipitation in the western and eastern parts of the Czech Republic together with positive (negative) trend of the North Atlantic Oscillation index in winter (summer) may contribute to the longitudinal dependency of the precipitation trends.