Cases of mass development of intrusions in Lake Baikal and the correlation of intrusions with atmospheric circulation processes

Abstract

Abstract. The cases of the development of mass intrusions in some basins of Lake Baikal were reviewed based on the measurements of water temperature and dissolved oxygen in water in 1993-2022. It was shown that in Southern, Middle and Northern Baikal during the development of intrusions in the spring-summer period, the heat deficit value was within 0.5-103.0, 3.1-15.8, 0.2-3.6 MJ/m2, dissolved oxygen amount was 0.2-161.3, 14.7-46.0, 0.6-6.3 g/m2 and the renewed bottom layer thickness was 36-318, 48-176, 38-94 m respectively. In winter in Southern Baikal, the heat deficit value varied within 0.8-5.2 MJ/m2, the amount of dissolved oxygen was 9.9-19.2 g/m2, and the thickness of the renewed bottom layer was 24-124 m. Analysis of the correlation between the heat deficit values and the circulation indices revealed that mass intrusions in Southern and Northern Baikal during the spring-summer period were associated with the prevailing meridional transport of air masses from the Eastern Atlantic and blocking zonal transport of air masses from the Atlantic and Pacific Oceans. On the contrary, in Middle Baikal, mass intrusions during the spring-summer period were developing under the conditions of zonal transport of air masses simultaneously from the Eastern Atlantic and northern and western areas of the Pacific Ocean. The development of mass intrusions in Southern Baikal in winter was related to the intensification of circumpolar circulation and zonal transport of air masses from the Atlantic Ocean.