Estimation of mixing efficiency of a small dimictic lake due to surface cooling
S. R. Bogdanov,
N. I. Palshin,
R. E. Zdorovennov,
A. V. Mitrokhov,
P. S. Kuznetsov,
J. S. Novikova,
G. E. Zdorovennova https://doi.org/10.59887/2073-6673.2023.16(2)-6
Abstract
The paper presents the results of studying the mixing of the water mass of a small forest dimictic lake at the stage of summer heating. The wind effect is limited by the small area of the mirror (the size of the lake is 80–110 by 400 m) and the forested shores, so in summer the convective mixing mechanism prevails when the lake surface cools at night. Evaluation of the mixing efficiency η was carried out by the integral energy method, based on the calculations of energy pumping and changes in the background potential energy according to the temperature profile transformation. For this purpose, a chain with 13 highly sensitive temperature sensors was used; the measurements were carried out in the middle of summer 2022 for 35 days with a time interval of one minute. Acoustic current profiler’s data were used to estimate turbulent velocity fluctuations and calculate the energy dissipation rate, which made it possible to make an alternative assessment of the mixing efficiency. The value of η ~0,4 was obtained, which significantly exceeds the “canonical” value of 0,17 for the case of wind mixing.
Keywords
a small dimictic lake,
water temperature,
buoyancy flux,
energy dissipation rate,
available potential energy,
mixing efficiency
Supporting agencies: This work was supported by Russian Science Foundation grant 21-17-00262, “Mixing in Boreal Lakes: Mecha- nisms and its effeciency”.
About the Authors
S. R. Bogdanov
Northern Water Problems Institute of the Karelian Research Centre of RAS
Russian Federation
Russian Federation
185030, Aleksander Nevsky st., 50 Petrozavodsk, Republic of Karelia
N. I. Palshin
Northern Water Problems Institute of the Karelian Research Centre of RAS
Russian Federation
Russian Federation
185030, Aleksander Nevsky st., 50 Petrozavodsk, Republic of Karelia
R. E. Zdorovennov
Northern Water Problems Institute of the Karelian Research Centre of RAS
Russian Federation
Russian Federation
185030, Aleksander Nevsky st., 50 Petrozavodsk, Republic of Karelia
A. V. Mitrokhov
Northern Water Problems Institute of the Karelian Research Centre of RAS
Russian Federation
Russian Federation
185030, Aleksander Nevsky st., 50 Petrozavodsk, Republic of Karelia
P. S. Kuznetsov
Northern Water Problems Institute of the Karelian Research Centre of RAS
Russian Federation
Russian Federation
185030, Aleksander Nevsky st., 50 Petrozavodsk, Republic of Karelia
J. S. Novikova
Northern Water Problems Institute of the Karelian Research Centre of RAS
Russian Federation
Russian Federation
185030, Aleksander Nevsky st., 50 Petrozavodsk, Republic of Karelia
G. E. Zdorovennova
Northern Water Problems Institute of the Karelian Research Centre of RAS
Russian Federation
Russian Federation
185030, Aleksander Nevsky st., 50 Petrozavodsk, Republic of Karelia
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For citations:
Bogdanov S.R., Palshin N.I., Zdorovennov R.E., Mitrokhov A.V., Kuznetsov P.S., Novikova J.S., Zdorovennova G.E. Estimation of mixing efficiency of a small dimictic lake due to surface cooling. Fundamental and Applied Hydrophysics. 2023;16(2):73-88. (In Russ.) https://doi.org/10.59887/2073-6673.2023.16(2)-6
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