Distribution of extreme wet and dry days in Estonia in last 50 years

摘要

Estimation of extreme wet and dry weather conditions on the basis of moving average of daily precipitation allows to determine the most drastic periods and trends of the precipitation regime in Estonia in last 50 years.The wet and dry days have been selected from the calculation results of the precipitation moving average.A day is considered as extreme wet when the moving average of the daily precipitation is at least 10 mm on 10 successive days till this day.A day is considered as extreme dry when there was no precipitation during 20 successive days till the observed day.Inter-annual variability of the average number of wet and dry days in Estonia has remarkably grown in 1957-2006;the years with a large number of wet or dry days can be easily distinguished.The increase of the annual total number of extreme(wet and dry) days is obvious.