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Summary:
Vertical Discretization
The article discusses the vertical discretization of lakes in the CLM (Community Land Model) model. Key points:
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Each grid cell currently contains one lake with prescribed or assumed depth, extinction coefficient, and fetch. This could be modified in future model versions.
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The lake consists of:
- 0-5 snow layers
- 10 (global simulations) or 25 (site simulations) water and ice layers for the "lake body"
- 10 "soil" layers
- 5 bedrock layers
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The water mass in each lake body layer is fixed, with the frozen mass-fraction as a state variable.
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Resolved snow layers are present if the snow thickness meets a minimum threshold (4 cm by default).
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The default layer thicknesses for global (50 m depth) and site simulations are provided.
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For lakes with depths other than 50 m, the top layer is kept at 10 cm, and the other layers are adjusted to maintain fixed proportions. For lakes less than 1 m deep, all layers have equal thickness.
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The snow, soil, and bedrock layer thicknesses follow the scheme used over non-vegetated surfaces, with modifications to the snow layer thickness rules.