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Drivers of deep‐water renewal events observed over 13 years in the S outh B asin of L ake B aikal
Author(s) -
Tsimitri Chrysanthi,
Rockel Burkhardt,
Wüest Alfred,
Budnev Nikolay M.,
Sturm Michael,
Schmid Martin
Publication year - 2015
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2014jc010449
Subject(s) - hypolimnion , downwelling , structural basin , geology , environmental science , spring (device) , oceanography , climatology , upwelling , mechanical engineering , paleontology , chemistry , organic chemistry , nutrient , eutrophication , engineering
Lake Baikal, with a depth of 1637 m, is characterized by deep‐water intrusions that bridge the near‐surface layer to the hypolimnion. These episodic events transfer heat and oxygen over large vertical scales and maintain the permanent temperature stratified deep‐water status of the lake. Here we evaluate a series of intrusion events that reached the bottom of the lake in terms of the stratification and the wind conditions under which they occurred and provide a new insight into the triggering mechanisms. We make use of long‐term temperature and current meter data (2000–2013) recorded in the South Basin of the lake combined with wind data produced with a regional downscaling of the global NCEP‐RA1 reanalysis product. A total of 13 events were observed during which near‐surface cold water reached the bottom of the South Basin at 1350 m depth. We found that the triggering mechanism of the events is related to the time of the year that they take place. We categorized the events in three groups: (1) winter events, observed shortly before the complete ice cover of the lake that are triggered by Ekman coastal downwelling, (2) under‐ice events, and (3) spring events, that show no correlation to the wind conditions and are possibly connected to the increased spring outflow of the Selenga River.