Other WRF Physics Options¶
Physics Contents¶
WRF Physics Overview
Cumulus Parameterization
Microphysics
Radiation
Planetary Boundary Layer (PBL) Physics
Surface Physics
Using Physics Suites
Physics Options for Specific Applications
Quicklinks to Specific Applications¶
Click on a link below to skip ahead to a specific application.
Surface Irrigation Parameterization
Tropical Storms and Cyclones¶
Options to use for tropical storms and tropical cyclone/typhoon/hurricane applications
sf_ocean_physics=1 : simple 1-D ocean mixed layer model following that of Pollard et al., 1972. Two other namelist options are available to specify the initial mixed layer depth (although one may ingest real mixed layer depth data) (oml_hml0) and a temperature lapse rate below the mixed layer (oml_gamma). This option works with all sf_surface_physics options.
oml_hml0 : Ocean mixed-layer depth; a setting < 0 initializes with real-time ocean mixed depth, and setting the value to =0 initializes with climatological ocean mixed depth.
oml_gamma : oml deep water lapse rate (K m-1)
sf_ocean_physics=2 : 3D Price-Weller-Pinkel (PWP) ocean model based on Price et al., 1994. This model predicts horizontal advection, pressure gradient force, and mixed layer processes. Only simple initialization via namelist variables ocean_z, ocean_t, and ocean_s is available.
ocean_z : vertical profile of layer depths for ocean (in meters)
ocean_t : vertical profile of ocean temps (K)
ocean_s : vertical profile of salinity
For e.g.,
&physics sf_ocean_physics = 2 &domains ocean_z = 5., 15., 25., 35., 45., 55., 65., 75., 85., 95., 105., 115., 125., 135., 145., 155., 165., 175., 185., 195., 210., 230., 250., 270., 290., 310., 330., 350., 370., 390. ocean_t = 302.3493, 302.3493, 302.3493, 302.1055, 301.9763, 301.6818, 301.2220, 300.7531, 300.1200, 299.4778, 298.7443, 297.9194, 297.0883, 296.1443, 295.1941, 294.1979, 293.1558, 292.1136, 291.0714, 290.0293, 288.7377, 287.1967, 285.6557, 284.8503, 284.0450, 283.4316, 283.0102, 282.5888, 282.1674, 281.7461 ocean_s = 34.0127, 34.0127, 34.0127, 34.3217, 34.2624, 34.2632, 34.3240, 34.3824, 34.3980, 34.4113, 34.4220, 34.4303, 34.6173, 34.6409, 34.6535, 34.6550, 34.6565, 34.6527, 34.6490, 34.6446, 34.6396, 34.6347, 34.6297, 34.6247, 34.6490, 34.6446, 34.6396, 34.6347, 34.6297, 34.6247
isftcflx : Modify surface bulk drag (Donelan) and enthalpy coefficients to be more in line with recent research results of those for tropical storms and hurricanes. This option includes dissipative heating term in heat flux. It is only available for sf_sfclay_physics=1. There are two options for computing enthalpy coefficients:
isftcflx=1: constant Z0q for heat and moisture
isftcflx = 2 Garratt formulation, slightly different forms for heat and moisture
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Long Simulations¶
tmn_update=1 : update deep soil temperature
sst_skin=1 : calculate skin SST based on Zeng and Beljaars, 2005
bucket_mm=1 : bucket reset value for water equivalent precipitation accumulations (value in mm, -1=inactive)
bucket_J: bucket reset value for energy accumulations (value in Joules, -1=inactive); only works with CAM and RRTMG radiation options (ra_lw_physics = 3, 4, 14, 24 and ra_sw_physics = 3, 4, 14, 24)
To drive the WRF model with climate data that does not include a leap year, prior to compiling WRF, edit the configure.wrf file by adding -DNO_LEAP_CALENDAR to the macro “ARCH_LOCAL.”
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Windfarm¶
windfarm_opt=1
Wind turbine drag parameterization scheme. It represents sub-grid effects of specified turbines on wind and TKE fields. The physical charateristics of the wind farm is read-in from a file; use of the manufacturer’s specification is recommeded. An example of the file is provided in “run/wind-turbine-1.tbl.” The location of the turbines are read-in from the file “windturbines.txt.” See “README.windturbine” in the WRF/doc/ directory for more detail. This option only works with 2.5 level MYNN PBL option (bl_pbl_physics=5).
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Surface Irrigation Parameterization¶
Three irrigation schemes added in V4.2 allow representation of surface irrigation processes within the model, with explicit control over water amount and timing (for more information refer to Vira et al., 2019). The schemes are set in the “&physics” namelist and represent different techniques, depending on the water evaporative loss in the application process. The evaporative processes consider loss from:
sf_surf_irr_scheme=1 : surface evapotranspiration; only works with Noah-LSM
sf_surf_irr_scheme=2 : leaves/canopy interception and surface evapotranspiration
sf_surf_irr_scheme=3 : microphysics process, leaves/canopy interception and surface evapotranspiration
The daily irrigation water amount applied is defined in “irr_daily_amount” (mm/day). The period within the day for the application starts at “irr_start_hours” UTC and lasts for “irr_num_hours.” The period within the year where irrigation is applied is defined by Julian days within “irr_start_julianday” and “irr_end_julianday.” To account for greater than daily irrigation intervals “irr_freq” can be set to a value greater than 1; thus water applied in the active day within the “irr_freq” period is ( irr_daily_amount * irr_freq ). “irr_ph” regulates spatial activation of irrigation (with irr_freq >1), especially determining whether it is activated for all domains on the same day (irr_ph = 0). Two options are given for irr_ph not equal to 0:
irr_ph=1 : activation field as a function of ( i , j , IRRIGATION)
irr_ph=2 : activation field is created with the fortran RANDOM function
Given the possibility of multiple nests in WRF, irrigation schemes should run on only one domain for each simulation. This ensures the water application is not repeated and is consistent to the irr_daily_amount calculated. For additional information regarding the code changes, see GitHub Code Commit 9bd5b61d9a.
Example of irrigation namelist parameters for a two domain case:
sf_surf_irr_scheme = 0, 1
irr_daily_amount = 0, 8
irr_start_hour = 0, 14
irr_num_hours = 0, 2
irr_start_julianday = 0, 121
irr_end_julianday = 0, 170
irr_ph = 0, 0
irr_freq = 0, 3
These settings use the channel method to irrigate the inner domain starting at 14 UTC for 2 hours, with a value of 8mm/day. Irrigation starts on Julian day 121 and ends on Julian day 170. Water is applied to the entire inner domain for all irrigated grid-points simultaneously, every 3 days (irr_freq=3). This leads to an hourly irrigation of 12 mm/h (daily application of 24 mm), which is then multiplied by the irrigation percentage within the grid-cell (given by the IRRIGATION field processed in WPS).
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Physics Sensitivity Options¶
no_mp_heating=1 : turns off latent heating from microphysics. When using this option, cu_physics should be set to 0.
icloud=0 : turns off cloud effect on optical depth in shortwave/longwave radiation options 1 and 4. Note, this namelist also controls which cloud fraction method to use for radiation.
isfflx=0 : turns off both sensible and latent heat fluxes from the surface. This option works for sf_sfclay_physics = 1, 5, 7, 11.
ifsnow=0 : turns off snow effect in sf_surface_physics=1.
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