glm-setup

name: glm-setup description: Running the General Lake Model (GLM) and understanding its NML configuration file format.

GLM Setup and Configuration

Running GLM

GLM is run from the directory containing glm3.nml:

cd /path/to/sim && glm

Key NML Sections

• &glm_setup: Layer configuration
• &light: Light attenuation (Kw = light extinction coefficient)
• &mixing: Mixing parameters (coef_mix_hyp = hypolimnetic mixing)
• &meteorology: Met forcing adjustments (wind_factor, sw_factor, lw_factor, cd, ce, ch)
• &time: Simulation period (start, stop, dt)
• &output: Output directory and file naming
• &init_profiles: Initial temperature/salinity profiles
• &morphometry: Lake bathymetry
• &inflow/&outflow: Hydrological boundary conditions

Output

• NetCDF file at <out_dir>/<out_fn>.nc
• Contains variables: temp (temperature), salt, etc.
• Dimensions: time × depth (layers vary per timestep)
• z variable gives height above bottom; convert to depth = lake_depth - z

NML Editing

Fortran namelist format. Parameters are key = value pairs within &section ... / blocks.