Ice Phenomena of the Middle Siberia Rivers for the Period of the Last 300 Years (according to historical data) as a Reflection of the Climate Changes

Abstract

The study represents the analysis results of the long-term time series of observation of ice breaking and freezing of the Siberian Rivers (the Ob, the Irtysh, the Yenisei, the Angara, etc.). There have been obtained statistic characteristics of the dependence of ice events dates on spring and autumn temperatures. We prove that during two last centuries there has been a steady trend towards shifting of ice-breaking moments for earlier ones and freezing dates for latter periods. We have specified common features of the variability of ice breaking and freezing periods, and there have been singled out the periods of fall in general temperature in the territory of Siberia for the last 300 years. On the basis of tree-ring chronologies data, there has been revealed a connection between the indirect indicator of summer temperatures change (tree growth) and the period of open water. The results of the work significantly enlarge the knowledge of variability of the Siberian climate for the previous centuries. Two last centuries are characterized by the steady trend of shift of ice-breaking moments towards earlier dates and those ones of freezing - towards later periods. So the long-term time series of ice events (especially the period of open water) are the indication of warming over the considerable territory of Southern Siberia, that confirms the general tendency of warming in the temperate latitudes of the Northern Hemisphere. There was found out a multi-directed trend in the ice events and long temperature-sensitive tree-ring chronologies after the 1950s. As the ice events are the consequence of physical processes, the cause of the divergence is necessary to be looked for in the biological response of trees for the climate changes or in other active biological factors of the environment. The revealed close connection between ice events and the temperature of some months gives an opportunity to use the statistical characteristics for the forecast of ice events dynamics of the Siberian Rivers, especially for the warming impacts.

В работе представлены результаты анализа длительных рядов наблюдения по вскрытию и замерзанию рек на территории Сибири. Получены статистические характеристики зависимости дат ледовых явлений от весенних и осенних температур. Показано, что для двух последних столетий характерен устойчивый тренд на смещение моментов вскрытия на более ранние, а замерзания на более поздние сроки. Установлены общие черты изменчивости сроков вскрытия-замерзания и выделены периоды общего понижения температуры на территории Сибири за последние 300 лет. На основе привлечения данных древесно-кольцевых хронологий выявлена связь между косвенным индикатором изменения летних температур (приростом деревьев) и периодом открытой воды. Результаты работы существенно дополняют общие закономерности изменчивости климата Сибири за прошедшие столетия.