Values of mean precipitation have been estimated from time series obtained using
15- and 30-day totals of the daily precipitation, measured at 40 stations throughout Estonia over a 45-year period (1961–2005). Six series were studied using different spatially averaged scales. The temporal variability of each series was fitted using an autoregressive and integrated moving-average (ARIMA) model of type IMA(0,1,1). The fitted model was non-stationary but allowed a formal decomposition into a stationary white noise and a non-stationary random walk component. The standard deviation of the stationary component was then used to define a 95% range of variability for the precipitation that divides the distribution into three regimes, a central and two outlying parts. We herein present simple statistics for each of these three regimes.
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