Changes in River Ice Formation Dates and Tests for Their Statistical Significance Assessment

摘要

A methodological approach is developed to the analysis of long-term series of observations of hydrological characteristics including the testing of the hypothesis of randomness both for the full series and for their parts; the diagnosis of intraseries dependence of time series; the testing of the hypothesis of homogeneity of the parts of observations series under comparison; the identification of change points. Statistically significant changes in the dates of river ice formation in the Votkinsk Reservoir catchment were revealed for the periods of 1975-2012 and 1983-2012, whereas the entire observation period (1936-2012) did not reveal such changes. A possibility of localization of change points for the observation series was assessed using the inversion test.