Module 2: Configuring Model Parameters

Getting Familiar with the .nml

To configure the model, open the glm3.nml file in the Kinneret97 directory with a text editor. A chunk of this .nml file is shown below. For example, if you wanted to change the maximum number of lake layers the model simulates, you would change max_layers = 500.

The easiest way to edit the glm3.nml file is with the Atom text editor. You can download it here.

!------------------------------------------------------------------------------!
!                                                                              !
!          .----------------.  .----------------.  .----------------.          !
!          | .--------------. || .--------------. || .--------------. |        !
!          | |    ______    | || |   _____      | || | ____    ____ | |        !
!          | |  .' ___  |   | || |  |_   _|     | || ||_   \  /   _|| |        !
!          | | / .'   \_|   | || |    | |       | || |  |   \/   |  | |        !
!          | | | |    ____  | || |    | |   _   | || |  | |\  /| |  | |        !
!          | | \ `.___]  _| | || |   _| |__/ |  | || | _| |_\/_| |_ | |        !
!          | |  `._____.'   | || |  |________|  | || ||_____||_____|| |        !
!          | |              | || |              | || |              | |        !
!          | '--------------' || '--------------' || '--------------' |        !
!          '----------------'  '----------------'  '----------------'          !
!                                                                              !
!-------------------------------------------------------------------------------

!-------------------------------------------------------------------------------
! general model setup
!-------------------------------------------------------------------------------
&glm_setup
   sim_name = 'Example Kinneret GLM Simulation'
   max_layers = 500
   min_layer_vol = 0.025
   min_layer_thick = 0.15
   max_layer_thick = 1.50
   density_model = 1
/

Exercise: Adding Output Points

Go to the &output section of glm3.nml and customize the configuration to make two output files, one at 5m from the bottom (ie. in the lake hypolimnion) and one at 35m from the bottom (ie. in the lake epilimnion). This create two .csv files (WQ_5.csv and WQ_35.csv) with conditions at these water depths. Plot the temperate of the two layers in excel. Identify the periods where the lake is stratified and mixed.

!-------------------------------------------------------------------------------
! format for output and filename(s)
!-------------------------------------------------------------------------------
&output
   out_dir = 'output'
   out_fn  = 'output'
   nsave = 6  !This will output every 6 hours
   ! General summary file
   csv_lake_fname = 'lake'
   ! Depth specific outputs
   csv_point_nlevs = 2 
   csv_point_fname = 'WQ_'
   csv_point_at = 5.,35.
   csv_point_nvars = 4
   csv_point_vars = 'temp','salt','PHS_frp','NIT_amm'
/

Assess how the degree of stratification changes as the initial water level of the lake is reduced by 20m. To do this change the initial starting lake depth and profile details in glm3.nml.

You will need to update the output depth of your surface output file.

For future activities make sure you change back to 43m.