DOI: 10.5194/hess-24-1691-2020
论文题名: Turbulence in the stratified boundary layer under ice: Observations from Lake Baikal and a new similarity model
作者: Kirillin G. ; Aslamov I. ; Kozlov V. ; Zdorovennov R. ; Granin N.
刊名: Hydrology and Earth System Sciences
ISSN: 1027-5606
出版年: 2020
卷: 24, 期: 4 起始页码: 1691
结束页码: 1708
语种: 英语
Scopus关键词: Atmospheric thermodynamics
; Boundary layer flow
; Boundary layers
; Budget control
; Heat flux
; Kinetic energy
; Kinetics
; Lakes
; Mixing
; Shear flow
; Thermal stratification
; Density stratification
; Ice-water interfaces
; Scaling relationships
; Stratification effects
; Stratified boundary layers
; Turbulent energy budgets
; Turbulent kinetic energy
; Turbulent transports
; Ice
; buoyancy
; energy budget
; heat flux
; ice lake
; kinetic energy
; melting
; mixing
; model test
; seasonality
; stratification
; turbulent boundary layer
; Lake Baikal
; Russian Federation
英文摘要: 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. © 2020 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/162738
Appears in Collections: 气候变化与战略
There are no files associated with this item.
作者单位: Kirillin, G., Department of Ecohydrology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany; Aslamov, I., Department of Hydrology and Hydrophysics, Limnological Institute, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russian Federation; Kozlov, V., Institute for System Dynamics and Control Theory, Siberian Branch of Russian Academy of Science, Irkutsk, Russian Federation; Zdorovennov, R., Northern Water Problems Institute (NWPI), Karelian Research Center, Russian Academy of Sciences, Petrozavodsk, Russian Federation; Granin, N., Department of Hydrology and Hydrophysics, Limnological Institute, Siberian Branch of Russian Academy of Sciences, Irkutsk, Russian Federation
Recommended Citation:
Kirillin G.,Aslamov I.,Kozlov V.,et al. Turbulence in the stratified boundary layer under ice: Observations from Lake Baikal and a new similarity model[J]. Hydrology and Earth System Sciences,2020-01-01,24(4)