...
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 parameter to set is called 'KntRad_S' from the 'gem_settings.nml'. It should following parameters of the namelist 'physics_cfgs' can get set to a multiple 4 to 6 of the model timestep. The unit is seconds.
Resolution → (non) hydrostatic
.
'kntrad_S' : Time between full radiation calculation (units D,H,M,S,P)
'kntraduv_S' : Time between UV radiation calculation (units D,H,M,S,P)
Resolution → (non) hydrostatic
If the 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.'
...
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:
...
At the beginning of every simulations several fields (atmospheric, surface and soil) need to get initialized. Especially for short simulations it is very important to use fields that best represent the starting state of a simulation. If such fields are not available one can also chose choose to spinup the simulation. Whereas atmospheric fields get into equilibrium very quickly, surface fields like snow on the ground might take up to at least a season. Soil fields, like soil temperature and soil moisture, can take several years to get into equilibrium, depending on the soil depth.
...
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'.
Land surface scheme (ISBA, CLASS, SVS)
One needs to chose 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
ISBA
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.
...
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
Lake scheme (non, FLake, CSLM)
One needs to chose 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:
'NIL' : Lakes get treated my water routine routine (default) => Prescribed SST and SIC will get used
'FLAKE' : FLake lake scheme
'CSLM' : Canadian Small Lake Model
Urbain scheme (non, TEB)
One needs to chose choose a lake scheme that calculates the heat fluxes and diagnostic fields over the urban fraction. The parameter 'schmurb' from the namelist 'surface_cfgs' needs to get set to one of the following:
'NIL' : No Urban surface processes processes (default) => the urban fraction will get taken care of by the land surface model - see above
'TEB' : Town Energy Balance (TEB) urban scheme
If 'TEB' is chosenchoosen, 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.
Radiation
Roughness length
Limit ice /snow
Gravity wave drag
Emissivity
Condensation
Convection
Tracers to advect
Precipitation (Bourgouin)
Boundary layer
Horizontal diffusion
Output fields
Output fields
Instantaneous / averages / min / max
Initial condition fields
Pilot fields (2-D / 3-D)
Output frequency
Output levels
Size of output files (monthly/daily/hourly/...)
Submission
Account
Wall clock time
On the clusters of the Alliance are different queues for jobs requesting different amounts of walltime as well as memory. To find out which type of queues exist on the cluster you want to run on check out the following wiki of the Alliance: Job_scheduling_policies
In the config file 'configexp.cfg' set 'BACKEND_time_mod' to the amount of seconds you want to request for a single job(1) - not for the whole simulation which can consist of multiple jobs.
In general, the shorter the requested time the shorter the queued time. Therefore, you want to request as little time as possible for a job. However, runtimes on clusters of the Alliance can vary by a lot, normally between -15 % to + 20 % of the average runtime. Hence, one should request runtimes that are about 25 % larger than the average expected runtime.
If you only want to run one job you can just request "enough" runtime. But when you are running a simulation with a sequence of jobs you might want to try to fit the jobs at the higher end of a queue. For Assuming, there are the following queues on a cluster:
- 3 hours or less,
- 12 hours or less,
- 24 hours (1 day) or less,
- 72 hours (3 days) or less,
And the simulation you want to run usually needs 14 hours per job.
...
Emissivity
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'
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 '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.
Turbulent orographic form drag
By default, part of the unresolved topography gets "added" as an orographic roughness length to the roughness length of the surface schemes. But instead one can also use a turbulent orographic form drag scheme. To do this the following parameters of the namelist 'physics_cfgs' can get set to:
Tofd = 'beljaars04'
Tofd_alpha = 35.
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
For resolutions of 10 km and lower we usually use 'consun'. For resolutions of 4 km and higher 'MP_P3'. However, 'MP_P3' can also get used at lower resolutions (down to 12 km), especially when the output is used to drive a higher resolution simulation that uses 'MP_P3'.
When using stcond = 'MP_P3' one should also set the following parameters from the namelist 'gem_cfgs', for example to:
p3_ncat = 1
p3_depfact = 1.0
p3_subfact = 1.0
p3_debug = .false.
p3_scpf_on = .true.
p3_pfrac = 1.
p3_resfact = 0.46
p3_clip_qv = .true.
Tracers to advect
Depending on the condensation scheme, several tracers can get chosen to get advected by setting the parameter 'Tr3d_list_S' from the namelist 'gem_cfgs'. For example:
for 'stcond = consun':
Tr3d_list_S = 'HU,wload=0,mono=2,mass=1,hzd=0,min=0.',
'QC,wload=1,mono=2,mass=1,hzd=0,min=0.'
for 'stcond = MP_P3':
Tr3d_list_S = 'HU , wload=0,mono=2,mass=1,hzd=0,min=0.',
'MPQC, wload=1,mono=2,mass=1,hzd=0,min=0.',
'MPNC, wload=0,mono=2,mass=1,hzd=0,min=0.',
Precipitation (Bourgouin)
To improve the precipitation type(!) (not the quantity) an extra scheme can get used by setting the parameter 'pcptype' from the namelist 'gem_cfgs' can get set to one of the following:
'NIL' : no call to bourge (default)
'BOURGE' : use Bourgouin algorithm (bourge1) to determine precip. types - can sometimes improve the type of precipitation when using 'stcond = MP_P3'
'BOURGE3D' : 3-D version of the Bourgouin algorithm - should get used when using 'stcond = consun'.
Boundary layer
A boundary layer scheme should get chosen by setting 'fluvert' from the namelist 'gem_cfgs' to one of the following:
'NIL' : no vertical diffusion (default)
'CLEF' : non-cloudy boundary layer formulation
'MOISTKE' : cloudy boundary layer formulation
'SIMPLE ' : a very simple mixing scheme for neutral PBLs
Usually, we are choosing either 'CLEF' or 'MOISTKE'.
When using fluvert = 'MOISTKE' one can also set the following parameter from the namelist 'gem_cfgs', for example to:
Fnn_reduc = 1.0 ,
Fnn_mask = .false. ,
Mixing length
The mixing length calculation scheme should get set by setting the parameter 'longmel' from the namelist 'gem_cfgs' to one of the following:
'BLAC62' : mixing length calc. using Blackadar
'BOUJO' : mixing length calc. using Bougeault
'TURBOUJO' : mixing length calc. using Bougeault in turbulent regimes (otherwise Blackadar)
'LH' : mixing length calc. using Lenderink and Holtslag
Horizontal diffusion
Convection
The shallow convection scheme should get set by setting the parameter 'shal' from the namelist 'convection_cfgs' to one of the following:
'NIL' (default)
'KTRSNT'
'KTRSNT_MG' (not recommended)
'BECHTOLD'
The deep convection scheme should get set by setting the parameter 'deep' from the namelist 'convection_cfgs' to one of the following:
'NIL' :
'SEC' :
'OLDKUO' :
'KUOSTD' :
'KFC' :
'KFC2' :
'KFC3' :
'BECHTOLD' :
Output fields
Have a look at the following wiki page to learn more about the format of the file 'outcfg.out', in which all output fields need to get specified, apart from station data (see below): outcfg.out
One needs to define the output:
grid - choices are : model, core, free
frequency - either in number of timesteps or hours
level - level type, either model or pressure levels
2-D output fields
Instantaneous / averages / min / max
If a field is an average (average), a minimum (min), a maximum (max), an accumulator (accum) or an accumulator to be averaged (avgacc) before output.
Initial condition fields
The output of fields that can later get used to initialize another simulation can get triggered by setting the parameter 'CLIMAT_out_anal' in the file configexp.cfg.
Pilot fields (2-D / 3-D)
The output of fields that can later get used to drive another simulation at the lateral boundaries can get triggered by setting the parameter 'CLIMAT_out_pilot' in the file configexp.cfg.
Size of output files (monthly/daily/hourly/...)
The following parameters of the namelist 'out' should get set to determine the size of the output files and the frequency at which the post processing should get triggered:
'Out3_close_interval_S' - output file size: monthly, daily, hourly, minutely, secondly files or one file per timestep
'Out3_postproc_fact' - interval after how many output files the post processing should get triggered
'Out3_pilot_unit_S' - file size for case pilot files (nm_*): monthly, daily, hourly, minutely, secondly files or one file per timestep
Timeseries for certain points
The output of certain fields for specific points can get set by setting the following parameters in the namelist 'series':
!# List of time series for surface variables
character(len=SER_STRLEN_VAR) :: P_serg_srsrf_s(NVARMAX) = ' '
!# List of time series for profile variables
character(len=SER_STRLEN_VAR) :: P_serg_srprf_s(NVARMAX) = ' '
!# Number of timesteps between time-series writeout
integer :: P_serg_srwri = 1
!# Times series package stops at this timestep
integer :: P_serg_serstp = huge(1)
!# Stations chosen in lat,lon for time-series
!# Format: "STN1_NAME",lat1,lon1, "STN2_NAME",lat2,lon2, ...
type(SER_STN_LALO_T) :: xst_stn_latlon(NSTATMAX)
Submission
Account
On clusters of the Alliance one needs to set under which allocation account a simulation should run. The default allocation account can get set in the file '~/.Account'. But it can get overwritten by exporting(!!!) the parameter 'RAPid' in the file configexp.cfg.
Wall clock time
On the clusters of the Alliance are different queues for jobs requesting different amounts of walltime as well as memory. To find out which type of queues exist on the cluster you want to run on check out the following wiki of the Alliance: Job_scheduling_policies
In the config file 'configexp.cfg' set 'BACKEND_time_mod' to the amount of seconds you want to request for a single job(1) - not for the whole simulation which can consist of multiple jobs.
In general, the shorter the requested time the shorter the queued time. Therefore, you want to request as little time as possible for a job. However, runtimes on clusters of the Alliance can vary by a lot, normally between -15 % to + 20 % of the average runtime. Hence, one should request runtimes that are about 25 % larger than the average expected runtime.
If you only want to run one job you can just request "enough" runtime. But when you are running a simulation with a sequence of jobs you might want to try to fit the jobs at the higher end of a queue. For Assuming, there are the following queues on a cluster:
- 3 hours or less,
- 12 hours or less,
- 24 hours (1 day) or less,
- 72 hours (3 days) or less,
And the simulation you want to run usually needs 14 hours per job.
Memory
By default, the maximum memory of the smallest compute nodes will get used. To use the default, the parameter 'BACKEND_cm' from the file configexp.cfg must be set to:
BACKEND_cm=
But it can get overwritten with any other value. Accepted units are 'M' and 'G'.