We investigated upwelling events in the pelagic area of Lake Baikal that developed during summer stratification (July-November) using a combination of in situ and satellite observations. These upwellings appear in the centres of local cyclonic macrovortices with compensatory downwelling located on their periphery in coastal areas. The average duration of upwelling events was 5 weeks, with an observed maximum of 16 weeks. The most stable upwellings in Southern Baikal and over the Academician Ridge covered areas of up to 4,400 km 2 (59 % of Southern Baikal's surface) and 1,550 km 2 , respectively. Water was ascending in the upwelling zones at velocities of 1 9 10 -4 to 1.2 9 10 -2 cm s -1 . Temperature differences of 1-4°C and 2-13°C were observed between the downwelling and upwelling zones in the epilimnion and metalimnion, respectively. On the surface of the lake, water temperature can drop 4-7°C for water ascending from depths of 10-75 m, but the observed thickness of the layer within which water was ascending reached a depth of 280 m in August-September and 380 m in October; i.e. the ascending water included the entire upper layer (0-300 m). Geostrophic currents reached up to 24-38 cm s -1 on the boundary between up-and downwelling zones (usually 5-7 km offshore), but did not exceed 6-10 cm s -1 in the centres of upwelling zones.Comparison with other large lakes of the world is carried. This study is important for understanding the upwelling process that develops in Lake Baikal during summer stratification and can influence the heterogeneity of nutrients and primary production.

МЕТОДИКИ ДОЛГОСРОЧНОГО ПРОГНОЗИРОВАНИЯ СРОКОВ ПОЛНОГО ОЧИЩЕНИЯ ОТО ЛЬДА ВОДОХРАНИЛИЩ АНГАРО-ЕНИСЕЙСКОГО КАСКАДА Иркутский государственный университет, г. ИркутскОсновная цель настоящего исследования -разработка методик долгосрочного прогнозирования сроков полного очищения ото льда Красноярского, Иркутского, Братского и Усть-Илимского водохранилищ с использованием значений телеконнекционного индекса AO (Arctic Oscillation). Установленные в ходе исследования прогнозные зависимости позволяют предвидеть характер развития данного ледового явления со средней заблаговременностью от 29 до 46 сут., максимальной заблаговременностью -от 38 до 58 сут. Величина обеспеченности допустимой погрешности полученных прогностических зависимостей составляет от 89,5 до 94,7%, индекс корреляции имеет значения от 0,89 до 0,91, что определяет категорию качества предложенных методик прогнозирования сроков полного очищения ото льда Красноярского, Иркутского, Братского и Усть-Илимского водохранилищ как хорошую. Значения коэффициента прогностической информативности выше 0,82 демонстрируют временную устойчивость и возможность практического использования полученных методик прогнозирования.К л ю ч е в ы е с л о в а : индекс AO, ледовые прогнозы, полное очищение ото льда, Ангаро-Енисейский каскад. E.N. Sutyrina LONG-TERM FORECASTING TECHNIQUES FOR THE TERMS OF THE COMPLETE DISAPPEARANCE OF ICE ON RESERVOIRS OF THE ANGARA-YENISEI CASCADE Irkutsk State University, IrkutskThe main purpose of the research is to develop techniques for long-term forecasting of when there comes complete disappearance of ice on Krasnoyarsk, Irkutsk, Bratsk and Ust'-Ilimsk reservoirs using teleconnection AO (Arctic Oscillation) index values. The predictive dependencies obtained in the course of the study permit to anticipate forecasted ice phenomena with an average lead time from 29 to 46 days and maximum lead time from 38 to 58 days. The probability values for the margin of error of the received predictive dependencies are from 89.5 to 94.7%, their correlation index ranges from 0.89 to 0.91. Thus, the qualtity class for the proposed forecasting techniques for the terms of the complete disappearance of ice on Krasnoyarsk, Irkutsk, Bratsk and Ust'-Ilimsk reservoirs is identified as a good one. The values of prognostic information coefficient above 0.82 reveal the temporal stability and possibility of practical use of the predictive techniques obtained.K e y w o r d s : AO index, ice forecasts, complete disappearance of ice, Angara-Yenisei cascade

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