Ice break‐up on southern Lake Baikal and its relationship to local and regional air temperatures in Siberia and to the North Atlantic Oscillation

Abstract

The calendar date of ice break‐up on southern Lake Baikal has been recorded uninterruptedly since 1869. A strong trend to earlier thawing up to around 1920 (1 d per 3.3 yr) is followed by the lack of any significant trend thereafter. For the period 1931–1994, the timing of break‐up is related to local surface air temperatures integrated over periods of 1–3 months. Although highest unimodal correlations are with the 3‐month mean air temperature, a bimodal relationship between break‐up and air temperature exists at shorter integration times, with break‐up date being related not only to the air temperature prevailing during thawing (April) but also to that prevailing during the time of ice formation, when air temperatures are lowest (February). High frequency (interannual) fluctuations in the timing of break‐up appear to be influenced mainly by the air temperatures prevailing during thawing, and low‐frequency (interdecadal) fluctuations by those prevailing during ice formation. Whereas correlations with April air temperatures are always significant, those with February air temperatures are only significant during the latter part of this century, i.e., after cessation of the tendency toward earlier thawing.