Changes in the location, instrumentation and measurement times are documented for three Estonian meteorological stations during the last century. These metadata were used to check if such changes have introduced significant discontinuities into the time series of daily and monthly mean temperature, average wind speed and daily and monthly precipitation sums. For this purpose, time periods of the length of at least ten years were separated before and after each change and average values of meteorological elements during these periods were compared by means of the t-test at the significance level of 0.05. On the daily basis, such changes introduced an increase in all parameters under consideration. On the monthly basis, only wind speed and precipitation sums were affected in some cases. Earlier climatological analyses have shown that in Estonia the temperature has risen and the precipitation sums have increased. Therefore, it is very difficult to separate natural trends from the artificial changes.
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