CR 36:17-28 (2008)  -  DOI: https://doi.org/10.3354/cr00707

ABSTRACT: Ice cover persistence in the lower reaches of the Nemunas River has decreased during the last 150 yr. The variation in the river freeze- and break-up dates is related to climatic variables. The significance of the negative break-up trend exceeds that of the positive freeze-up trend. Low-frequency large-scale atmospheric circulation patterns such as the North Atlantic Oscillation and Arctic Oscillation (NAO/AO) appear to have more influence on the break-up date than on the freeze-up date. Different classification methods applied to the atmospheric patterns prevailing in the early freeze-up events reveal similar results; however, differences arising between classifications are attributable to non-persistent and high frequency patterns.

KEY WORDS: River ice cover · Freeze up · Break up · Atmospheric forcing