A study of heat transport at the ice base and structure of the under-ice water layer in Southern Baikal

Aslamov, Ilya; Козлов, В. В.; Kirillin, Georgiy; Mizandrontsev, I. B.; Kucher, K. M.; Макаров, М. М.; Granin, N. G.

doi:10.1134/s0097807817030034

Cited by 11 publications

(20 citation statements)

References 36 publications

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“…The high values of water-ice heat fluxes in Lake Baikal and their apparent relationship to the intensity of under-ice currents were previously noted by Aslamov et al (2014aAslamov et al ( , 2017. In the present study, the measured fluxes reached up to 40 W m −2 at their peaks, which is an order of magnitude higher than values reported from small Arctic lakes (Kirillin et al, 2018) and comparable to the highest reported values in alpine thermokarst ponds (Huang et al, 2019) and in the ocean (Gallaher et al, 2016;Peterson et al, 2017).…”

Section: Discussionsupporting

confidence: 65%

“…The resolution of the system was 0.002 • C for temperature, 0.1 W m −2 for solar radiation, and 0.1 mm for ice thickness (operational range of 0.2-2.8 m). The system collected data for a period of 2 min, logged them internally, and sent data several times a day via a cellular network to a remote Internet server (see Aslamov et al, 2017, for a detailed description of the ice station configuration). Two-dimensional electromagnetic current meters, "INFINITY-EM" (JFE Advantech Co., Ltd.), were used to measure the current velocities (velocity range: ±5 m s −1 ; resolution: 0.02 cm s −1 ; accuracy: ±1 cm s −1 ).…”

Section: Study Site and Field Methodsmentioning

confidence: 99%

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Turbulence in the stratified boundary layer under ice: observations from Lake Baikal and a new similarity model

Kirillin

Aslamov

Козлов

et al. 2020

Hydrol. Earth Syst. Sci.

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Seasonal ice cover on lakes and polar seas creates seasonally developing boundary layer at the ice base with specific features: fixed temperature at the solid boundary and stable density stratification beneath. Turbulent transport in the boundary layer determines the ice growth and melting conditions at the ice-water interface, especially in large lakes and marginal seas, where large-scale water circulation can produce highly variable mixing conditions. Since the boundary mixing under ice is difficult to measure, existing models of ice cover dynamics usually neglect or parameterize it in a very simplistic form. We present the first detailed observations on mixing under ice of Lake Baikal, obtained with the help of advanced acoustic methods. The dissipation rate of the turbulent kinetic energy (TKE) was derived from correlations (structure functions) of current velocities within the boundary layer. The range of the dissipation rate variability covered 2 orders of magnitude, demonstrating strongly turbulent conditions. Intensity of mixing was closely connected to the mean speeds of the large-scale under-ice currents. Mixing developed on the background of stable density (temperature) stratification, which affected the vertical structure of the boundary layer. To account for stratification effects, we propose a model of the turbulent energy budget based on the length scale incorporating the dissipation rate and the buoyancy frequency (Dougherty-Ozmidov scaling). The model agrees well with the observations and yields a scaling relationship for the ice-water heat flux as a function of the shear velocity squared. The ice-water heat fluxes in the field were the largest among all reported in lakes (up to 40 W m −2 ) and scaled well against the proposed relationship. The ultimate finding is that of a strong dependence of the water-ice heat flux on the shear velocity under ice. The result suggests large errors in the heat flux estimations when the traditional "bulk" approach is applied to stratified boundary layers. It also implies that under-ice currents may have much stronger effect on the ice melt than estimated by traditional models.

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Section: Discussionsupporting

confidence: 65%

Section: Study Site and Field Methodsmentioning

confidence: 99%

Turbulence in the stratified boundary layer under ice: observations from Lake Baikal and a new similarity model

Kirillin

Aslamov

Козлов

et al. 2020

Hydrol. Earth Syst. Sci.

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“…The assumption of conductive, turbulence-free IL does not hold true in large lakes, where under-ice water circulation is strong enough to produce long-lasting shear turbulence at the ice base: Aslamov et al (2014Aslamov et al ( , 2017 reported a strong, up to an order of magnitude, variability in the ice-water heat flux in Lake Baikal at synoptic time scales of several days and referred it to variations of the large-scale surface currents, as a part of geostrophic circulation in Lake Baikal. Aslamov et al (2014) also 25 demonstrated that the resulting increase of the heat supply from water to the ice cover may cancel the ice growth and produce bulk melting even at atmospheric temperatures below the freezing point of water and upward heat flux at the ice surface.…”

Section: Simmondsmentioning

confidence: 99%

“…As the ice gets thinner, and the stratification in the IL gets stronger, the role of the wind-induced mixing in the upward heat transport from the CL to the ice base is expected to significantly increase. The effect of the shear mixing under ice on the vertical heat transport is 15 akin to the shear turbulence produced by the geostrophic circulation in ice-covered Lake Baikal (Aslamov et al, 2014(Aslamov et al, , 2017, with one important difference: a strong lake-wide circulation under ice takes place only in very large lakes, while production of shear turbulence by fluctuations of the ice cover is expected to develop in the majority of ice-covered lakes. Aslamov et al (2014Aslamov et al ( , 2017 reported heat fluxes of up to 50 W m −2 at the ice base of Lake Baikal, associated with ε = O(10 −8 ) W kg −1 .…”

mentioning

confidence: 99%

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Turbulent mixing and heat fluxes under lake ice: the role of seiche oscillations

Kirillin¹,

Aslamov²,

Leppäranta³

et al. 2018

Preprint

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We performed a field study on mixing and vertical heat transport under ice cover of an Arctic lake. Mixing intensities were estimated from small-scale oscillations of water temperature and turbulent kinetic energy dissipation rates derived from current velocity fluctuations. Well-developed turbulent conditions prevailed in the stably stratified interfacial layer separating the ice base from the warmer deep waters. The source of turbulent mixing was identified as whole-lake (barotropic) oscillations of the water body driven by strong wind events over the ice surface. We derive a scaling of ice-water heat flux based on 5 dissipative Kolmogorov scales and successfully tested against measured dissipation rates and under-ice temperature gradients.The results discard the conventional assumption of nearly conductive heat transport within the stratified under-ice layer and suggest contribution of the basal heat flux into the melt of ice cover is higher than commonly assumed. Decline of the seasonal ice cover in the Arctic is currently gaining recognition as a major indicator of climate change. The heat transfer at the ice-water interface remains the least studied among the mechanisms governing the growth and melting of seasonal ice. The outcomes of 10 the study find application in heat budget of seasonal ice on inland and coastal waters. Copyright statement. Author(s) 2018 1 IntroductionSeasonal formation of ice cover is an essential feature of the hydrological regime of temperate and polar climatic zones. Freshwater lakes are, in this regard, a special class of hydrological objects, both in terms of thermal and hydrodynamic processes that 15 control the formation and melting of ice, and from the point of view of the impact of the ice regime of the global freshwater budget. The majority of world lakes is concentrated in the northern temperate and boreal environments between 40 • N and 80 • N and have the potential to freeze seasonally . Seasonally ice-covered lake systems-Lake Baikal, Laurentian Great Lakes, European Great Lakes Ladoga and Onego, lake systems of Fennoscandia and Northern Canadaaccumulate the bulk of the world's surface freshwater. Their seasonal ice regime determines climatic balance of precipitation 20 and evaporation, as well as the ecosystem state and the water quality of lakes themselves. The lakes of high latitudes remain less studied than temperate lakes, while arctic regions are reported to have the strongest air temperature increase (Screen and 1 Hydrol. Earth Syst. Sci. Discuss., https://doi.

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An analysis of ice growth and temperature dynamics in two Canadian subarctic lakes

Rafat

Pour

Spence

et al. 2023

Cold Regions Science and Technology

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A study of heat transport at the ice base and structure of the under-ice water layer in Southern Baikal

Cited by 11 publications

References 36 publications

Turbulence in the stratified boundary layer under ice: observations from Lake Baikal and a new similarity model

Turbulence in the stratified boundary layer under ice: observations from Lake Baikal and a new similarity model

Turbulent mixing and heat fluxes under lake ice: the role of seiche oscillations

An analysis of ice growth and temperature dynamics in two Canadian subarctic lakes

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