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Radiatively driven convection in ice-covered lakes: Observations, scaling, and a mixed layer model

Mironov, D; Terzhevik, A; Kirillin, G; Jonas, T; Malm, Joakim LU and Farmer, D (2002) In Journal of Geophysical Research 107(C4).
Abstract
Penetrative convection is discussed where the instability is driven by radiative heating of water below the temperature of maximum density. Convection of this type occurs in ice-covered freshwater lakes in late spring, when the snow cover vanishes and solar radiation is absorbed beneath the ice cover. The vertical temperature structure, bulk mixed layer scaling, and mixed layer deepening are examined for a number of temperate and polar lakes. A bulk mixed layer scaling for this type of convection is based on energy arguments underlying the classical Deardorff convective scaling. The depth of the convective layer serves as an appropriate length scale. However, a modified scale that takes account of the energetics of a distributed radiation... (More)
Penetrative convection is discussed where the instability is driven by radiative heating of water below the temperature of maximum density. Convection of this type occurs in ice-covered freshwater lakes in late spring, when the snow cover vanishes and solar radiation is absorbed beneath the ice cover. The vertical temperature structure, bulk mixed layer scaling, and mixed layer deepening are examined for a number of temperate and polar lakes. A bulk mixed layer scaling for this type of convection is based on energy arguments underlying the classical Deardorff convective scaling. The depth of the convective layer serves as an appropriate length scale. However, a modified scale that takes account of the energetics of a distributed radiation source term replaces the surface buoyancy flux velocity scale used by Deardorff. The scaling compares favorably with large-eddy simulations of turbulence kinetic energy (TKE) and with both observations and large-eddy simulations of the TKE dissipation rate. Mixed layer deepening is simulated with a model of convection beneath lake ice. The model describes the structure of the stably stratified layer just beneath the ice with a stationary solution to the heat transfer equation; the structure of the entrainment layer is parameterized with a zero-order jump approach. The entrainment equation is derived from the mixed layer TKE budget and bulk mixed layer scaling. Entrainment regimes characteristic of convection beneath ice are analyzed. It is shown that if the Deardorff convective velocity scale is replaced with a scale incorporating the distributed buoyancy flux, the entrainment equation describing atmospheric and oceanic convective boundary layers also applies beneath the ice. Model predictions compare well with data from observations in a number of lakes. We propose and compare with observations an extension of the mixed layer model that allows for the inclusion of salinity. Although the salt concentration is low in most temperate and polar lakes, its dynamical effect can be significant close to the temperature of maximum density. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
scaling, convection, ice-covered lake, mixed layer model
in
Journal of Geophysical Research
volume
107
issue
C4
publisher
American Geophysical Union
external identifiers
  • wos:000178923600001
  • scopus:0037092388
ISSN
2156-2202
DOI
10.1029/2001JC000892
language
English
LU publication?
yes
id
1f900905-760b-4085-a067-e4c63d33abb6 (old id 324743)
date added to LUP
2007-11-02 12:01:35
date last changed
2017-09-03 03:45:03
@article{1f900905-760b-4085-a067-e4c63d33abb6,
  abstract     = {Penetrative convection is discussed where the instability is driven by radiative heating of water below the temperature of maximum density. Convection of this type occurs in ice-covered freshwater lakes in late spring, when the snow cover vanishes and solar radiation is absorbed beneath the ice cover. The vertical temperature structure, bulk mixed layer scaling, and mixed layer deepening are examined for a number of temperate and polar lakes. A bulk mixed layer scaling for this type of convection is based on energy arguments underlying the classical Deardorff convective scaling. The depth of the convective layer serves as an appropriate length scale. However, a modified scale that takes account of the energetics of a distributed radiation source term replaces the surface buoyancy flux velocity scale used by Deardorff. The scaling compares favorably with large-eddy simulations of turbulence kinetic energy (TKE) and with both observations and large-eddy simulations of the TKE dissipation rate. Mixed layer deepening is simulated with a model of convection beneath lake ice. The model describes the structure of the stably stratified layer just beneath the ice with a stationary solution to the heat transfer equation; the structure of the entrainment layer is parameterized with a zero-order jump approach. The entrainment equation is derived from the mixed layer TKE budget and bulk mixed layer scaling. Entrainment regimes characteristic of convection beneath ice are analyzed. It is shown that if the Deardorff convective velocity scale is replaced with a scale incorporating the distributed buoyancy flux, the entrainment equation describing atmospheric and oceanic convective boundary layers also applies beneath the ice. Model predictions compare well with data from observations in a number of lakes. We propose and compare with observations an extension of the mixed layer model that allows for the inclusion of salinity. Although the salt concentration is low in most temperate and polar lakes, its dynamical effect can be significant close to the temperature of maximum density.},
  author       = {Mironov, D and Terzhevik, A and Kirillin, G and Jonas, T and Malm, Joakim and Farmer, D},
  issn         = {2156-2202},
  keyword      = {scaling,convection,ice-covered lake,mixed layer model},
  language     = {eng},
  number       = {C4},
  publisher    = {American Geophysical Union},
  series       = {Journal of Geophysical Research},
  title        = {Radiatively driven convection in ice-covered lakes: Observations, scaling, and a mixed layer model},
  url          = {http://dx.doi.org/10.1029/2001JC000892},
  volume       = {107},
  year         = {2002},
}