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Calculating the increments on different fields depending on the radiation is rather costly. Therefore, the option exists to calculate the increments only every n seconds but still apply them at every timestep. The following parameters of the namelist 'physics_cfgs' can get set to a multiple 4 to 6 of the model timestep.
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If the grid resolution is ~10 km or lower the model is hydrostatic and one should set 'Dynamics_hydro_L = .true.' in the namelist 'gemdyn_settings.nmlkernel'. For grid resolutions of ~4km and higher one should set 'Dynamics_hydro_L = .false.'
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Due to the semi-lagrangian advection scheme, which does not exactly conserve the total mass of the atmosphere, the GEM model is "loosing air" with time. Therefore, the parameter 'Schm_psadj' from the gem_settings.nml namelist 'dyn_fisl' needs to get set to one of the following:
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To get a list of fields that need to get provided have a look at the following wiki: Geophysical fields
Schemes
All schemes get set in the 'gem_settings.nml'.
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One needs to choose a land surface scheme that calculates the heat fluxes and diagnostic fields over the land fraction. The land fraction includes bare soil (desert) and vegetated areas. If no urban model (see below) is used it also includes the urban fraction. The parameter 'schmsol' from the namelist 'surface_cfgs' needs to get set to one of the following:
'NIL ' : No Land surface processes (default)
'ISBA' : Interaction Soil Biosphere Atmosphere (ISBA) land sfc scheme
'SVS ' : Soil, Vegetation, and Snow (SVS) (Multibudget) land sfc scheme
'CLASS': Canadian LAnd Surface Scheme
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If ISBA is chosen, the following other parameters from the namelist 'surface_cfgs' also need to get set:
!# If .true. apply temporary fix to ISBA
!# * timestep dependent KCOEF
!# * No PSN factor for meting and freezing
logical :: isba_melting_fix = .false.
!# Use the vegetation-only roughness length to compute vegetation snow fraction
logical :: isba_snow_z0veg = .false.
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If CLASS is chosen, the following other parameters from the namelist 'surface_cfgs' also need to get set:
!# Number of soil layers in CLASS
integer :: class_ig = 3
!# Soil layer thickness in CLASS
real :: schmsol_lev(200) = 0.0
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One needs to choose a lake scheme that calculates the heat fluxes and diagnostic fields over the land fraction. The parameter 'schmlake' from the namelist 'surface_cfgs' needs to get set to one of the following:
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One needs to choose a lake scheme that calculates the heat fluxes and diagnostic fields over the urban fraction. The parameter 'schmurb' needs to from the namelist 'surface_cfgs' needs to get set to one of the following:
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If 'TEB' is choosen, the following other parameters from the namelist 'surface_cfgs' also need to get set:
!# Adjust wind diagnostic in TEB with building height if .true.
logical :: urb_diagwind = .false.
!# Adjust temperature diagnostic in TEB in the street if .true.
logical :: urb_diagtemp = .false.
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For the following surface fractions the emissivity can get adjusted in the namelist 'surface_cfgs':
snow_emiss : Emissivity for snow, default 1, recommended '0.97'
water_emiss : Emissivity for water, default 1, recommended '1.0'
ice_emiss : Emissivity for ice (glacier and sea ice), default '0.99', recommended '0.97'
isba_soil_emiss : Emissivity for bare soil (ISBA scheme only), default '0.95', recommended 'climato'
Radiation
One needs to choose a radiation scheme. In general one chooses the latest one. Therefore, the parameter 'radia' needs to get set to one of the following:
Limit ice /snow
Due to biases, sea ice not drifting and glaciers not sliding downhill, sea ice and snow tend to get too think in certain places. Therefore, their depth can get limited by setting the parameters from the namelist 'surface_cfgs':
ICEMAX = 2.5 (recommended value)
SNOWMAX = 10. (recommended value)
Radiation
One needs to choose a radiation scheme. In general one chooses the latest one. Therefore, the parameter 'radia' from the namelist 'physics_cfgs' needs to get set to one of the following:
'NIL' : no radiation scheme (default)
'NEWRAD' : complete radiation scheme
'CCCMARAD' : most advanced radiation scheme
'CCCMARAD2': most advanced radiation scheme v2
When ' 'NIL' : no radiation scheme (default)
'NEWRAD' : complete radiation scheme
'CCCMARAD' : most advanced radiation scheme
'CCCMARAD2': most advanced radiation scheme v2
When 'cccmarad2' is chosen, one should also set the following parameters from the namelist 'physics_cfgs' to .true.:
!# Use climatological values of GHG in radiation (CCCMARAD2 only)
logical :: radghg_L =.false.
!# Use LINOZ prognostic Ozone in radiation (CCCMARAD2 .and. LINOZ only)
logical :: rad_linoz_L =.false.
Roughness length
Limit ice /snow
Due to biases, sea ice not drifting and glaciers not sliding downhill, sea ice and snow tend to get too think in certain places. Therefore, their depth can get limited by setting the parameters:
ICEMAX = 2.5 (recommended value)
SNOWMAX = 10. (recommended value)
Gravity wave drag
Emissivity
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Gravity wave drag
The parameter 'gwdrag' from the namelist 'physics_cfgs' should get set to one of the following:
'NIL' : no Gravity wave drag (default)
'GWD86' : gravity wave drag + low-level blocking
'SGO16' : new formulation (2016) of GWD86
The non-orographic GWD scheme, Hines, can get activated by setting the following parameter from the namelist 'physics_cfgs' to:
non_oro = .true. (default .false.)
Condensation
To select a condensation scheme the parameter 'stcond' from the namelist 'physics_cfgs' should get set to one of the following:
'NIL' : No explicit condensation scheme used (default)
'CONSUN' : Sunqvist type condensation scheme
'NEWSUND' : Sunqvist type condensation scheme
'MP_MY2_OLD' : Milbrandtl and Yau microphysics scheme (old formulation)
'MP_MY2' : Milbrandtl and Yau microphysics scheme
'MP_P3' : P3 microphysics scheme
Convection
Tracers to advect
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