WRF Output




WRF Output Fields

WRF outputs numerous variables to WRF history/output files (wrfout*) by default. Options are available to remove or add variables from wrfout* files, or to output variables to different files. Many variables are output dependent on options chosen during model configuration or for simulation (e.g., namelist.input settings). For e.g., a variable may be used by a specific physics scheme, and if that scheme is not chosen, it will not be calculated and output. After running WRF, issue the following command in a terminal window for a full list of wrf output variables:

ncdump -h wrfout_d<domain>_<date>





Special WRF Output Variables

WRF outputs state variables (defined in WRF/Registry/Registry.EM_COMMON) that are used in the model’s prognostic equations. The following state variables are perturbation fields, requiring the following reconstruction for meteorological standard fields:


Total Geopotential

PH + PHB

Total Geopotential Height (in meters)

(PH + PHB) / 9.81

Total Potential Temperature (in K)

T + 300

Total Pressure (in mb)

(P + PB) * 0.01

Wind Components (grid-relative)

U, V

Surface Pressure (in Pa)

psfc

Surface Winds (grid-relative)

U10, V10 (valid at mass points)

Surface Temperature

T2

Surface Mixing Ratio

Q2



Definitions for map projection (map_proj) options

1

Lambert Conformal

2

Polar Stereographic

3

Mercator

6

Latitude and Longitude (including global)





Run-Time I/O Option

Input/output (I/O) settings (e.g., which variables are output, and with which stream each variable is associated) are coded in WRF/Registry/* files. To change I/O settings, these files can be modified, but modifications to registry files require a time-consuming clean, reconfigure, and recompile of WRF. The Run-time I/O feature allows I/O modifications during WRF simulations, bypassing the need to recompile the model.

Note

Using Run-time I/O can cause a performance hit. For production runs, it is recommended to make registry changes instead of using this option.




Using the Run-time I/O Option

  1. Move to the wrf.exe execution directory and create a text file (e.g., my_file_d0X.txt; one for each domain) for defining output modifications. File content associates variables with a stream ID (e.g., stream 0 for default WRF history/output), specifying whether the field is added or removed. Examples are provided:


    The following removes fields RAINC and RAINNC from the standard WRF history/output file (stream 0 - wrfout_d0*):


    -:h:0:RAINC,RAINNC


    The following adds fields RAINC and RAINNC to an output stream 7, into files using the name defined in auxhist7_outname (see below):


    -:h:7:RAINC,RAINNC


    Available options are:

    + or -

    add or remove a variable

    0-24

    which stream to use

    i or h

    write to the input or history stream

    field name in the Registry file

    (string displayed in column 9 in the registry file)

    Available auxiliary streams are:

    Available Streams

    0-24

    0

    reserved for wrfout* files

    23

    reserved for pressure level diagnostic output

    3

    reserved for extreme climate

    2

    reserved for AFWA diagnostic output

    6

    reserved for RASM diagnostic output

    All other streams (except 1) are okay to use.




  2. Add the following to the &time_control section of namelist.input:


    &time_control
iofields_filename="my-file_d01.txt","my-file_d01.txt"
ignore_iofields_warning=.true.


    To output to a stream other than the WRF history/output stream 0, add the following to the &time_control namelist (modify the settings as needed) - e.g., output to stream 7:


    &time_control
auxhist7_outname="your-stream-name_d<domain>_<date>"
auxhist7_interval=360,360
frames_per_auxhist7=1, 1
io_form_auxhist4=2

    Note

    “your-stream-name” can be anything, but do not replace “_d<domain>_<date>.” That is the syntax the model looks for.




Additional notes regarding the Runtime I/O option

  • Do not include spaces between fields in the .txt file.

  • Variable names in the .txt file must identically match the quoted string from the Registry file (column 9)

  • It is not necessary to remove fields from one stream to add them to another. A field can be in multiple streams.

  • Fields listed in the .txt file must be declared as a state variable in the Registry.

  • The ignore_iofields_warning namelist parameter determines the model’s behavior if the .txt file contains an error. The default is .true., which prints a warning message, but continues the run. If set to .false., the simulation aborts if errors exist in the .txt file(s).






Output Diagnostics


Time Series Output

Outputting a time series of data at particular poionts in the domain can be useful for tracking the progression of particular variables. To do this, a file called tslist be added to the WRF running directory. This file should list each location, defined by its latitude and longitude (or i,j coordinates), along with a brief description and abbreviation, and the file should follow this format:

Note

The first three lines are regarded as header information, and are ignored by the model.


#-----------------------------------------------#
# 24 characters for name | pfx |  LAT  |   LON  |
#-----------------------------------------------#
Cape Hallett              hallt -72.330  170.250
McMurdo Station           mcm   -77.851  166.713


To use cell locations (e.g., for idealized cases), the i,j locations are specified as follows:

#-----------------------------------------------#
# 24 characters for name | pfx |   I   |    J   |
#-----------------------------------------------#
tower0001                 t0001  10       10
tower0002                 t0002  20       20
tower0003                 t0003  30       30



During wrf.exe the following files are written - one of each per location listed in tslist:

pfx*.d0x.TS

time series output of surface variables

pfx.d0x.UU

vertical profile of the u wind component for each time step

pfx.d0x.VV

vertical profile of the v wind component for each time step

pfx.d0x.WW

vertical profile of the w wind component for each time step

pfx.d0x.TH

vertical profile of potential temperature for time step

pfx.d0x.PH

vertical profile of geopotential height for each time step

pfx.d0x.QV

vertical profile of water vapor mixing ratio for each time step

pfx.d0x.PR

vertical profile of pressure for each time step

where

  • pfx : the location’s prefix specified in tslist

  • d0x : the domain ID, as given in namelist.input




namelist.input Variables Specific to Time-series Output


max_ts_locs

maximum number of locations in tslist ( default is 5)

ts_buf_size

buffer size for time series output (default is 200)

max_ts_level

number of model levels for time series vertical profiles (default is 15). The maximum number of max_ts_level is e_vert - 1 (the number of half layers in the model run)

tslist_unstagger_winds

output the unstaggered u, v, and w wind components (default is false)

Note

Locations specified in tslist that do not exist in any domain are ignored..


See also

See WRF/run/README.tslist for additional details.





Pressure Level Output

This option outputs the following extra fields to a number of pressure levels:

  • Wind speed (U and V)

  • Temperature (T)

  • Dewpoint temperature

  • Relative humididy (RH)

  • Geopotential Height



To activate this option, add the following record and parameters to namelist.input, making adjustments for the case:

&diags

p_lev_diags=1
num_press_levels=4
press_levels= 85000, 70000, 50000, 20000

/


The extra fields are output to auxiliary stream 23. Add the following variables to namelist.input. For e.g.,

& time_control

auxhist23_interval = 360, 360
frames_per_auxhist23 = 100, 100
io_form_auxhist23 = 2




Convective Storm Diagnostics

This option outputs the following extra fields to the WRF history/output file(s) (wrfout_d0*):

  • maximum 10 m wind speed

  • maximum helicity in the 2-5 km layer

  • maximum vertical velocity in updraft and downdraft below 400 mb

  • mean vertical velocity in the 2-5 km layer

  • maximum column graupel in a time window between WRF history/output times



To activate this option, add the following parameters to their specified namelist.input record:

&time_control
nwp_diagnostics = 1

&physics
do_radar_ref = 1




Climate Diagnostics

This option outputs surface diagnostic variables. For each of T2, Q2, TSK, U10, V10, 10 m wind speed, RAINCV, and RAINNCV, the following are calculated (a total of 48 additional variables):

  • maximum

  • minimum

  • the time at which the max occurs

  • the time at which the min occurs

  • mean value

  • standard deviation of the mean



Output goes to auxiliary stream 3. To activate this option, add the following parameters to namelist.input. For e.g.:

&time_control
output_diagnostics = 1
auxhist3_outname = "wrfxtrm_d<domain>_<date>"
auxhist3_interval = 1440, 1440
frames_per_auxhist3 = 100, 100
io_form_auxhist3 = 2


Note

Because many of these variables are computed, if doing a restart, it is advised to only restart at a multiple of auxhist3_interval.





Time-averaged Output

This option outputs history time-averaged column-pressure coupled U, V and W for downstream transport models. To activate this option, add the following parameter to namelist.input:

&dynamics
do_avgflx_em = 1


If a Grell cumulus scheme (cu_physics= 3, 5, or 93) is used, time-averaged convective mass fluxes can be output by adding the following parameter to namelist.input:

&dynamics
do_avg_cugd = 1




Weather Diagnostics

Contributed by the Air Force Weather Agency (AFWA)

This option outputs diagnostic variables to auxiliary stream 2. See AFWA Diagnostics in WRF for detailed documentation.


Note

This option cannot be used with code compiled with OpenMP.



To activate this option, add the following record and parameter to namelist.input:

&afwa
afwa_diag_opt=1
/


Then set any of the following options to 1 in the &afwa namelist record to output specific fields (set for each domain; default is 0=off).

&afwa

afwa_ptype_opt = 1,1

precipitation type

afwa_vil_opt = 1, 1

vertical integrated liquid

afwa_radar_opt = 1, 1

radar

afwa_severe_opt = 1, 1

severe weather

afwa_icing_opt = 1, 1

icing

afwa_vis_opt = 1, 1

visibility

afwa_cloud_opt = 1, 1

cloud

afwa_therm_opt = 1, 1

thermal indices

afwa_turb_opt = 1, 1

turbulence

afwa_buoy_opt = 1, 1

buoyancy


The following may also be set when afwa_ptype_opt=1:

&afwa

afwa_ptype_ccn_temp = 264.15

CCN temperature for precipitation type calculation

afwa_ptype_tot_melt = 50

total melting energy for precipitation type calculation




Solar Forecasting Diagnostics

This option outputs the following variables to the wrf output files (wrfout_d0*):

  • Solar zenith angle

  • Clearness index

  • 2D maximum cloud fraction

  • Paths for water vapor, liquid water, ice water, and snow water

  • Effective radius for liquid cloud, ice, and snow

  • Optical thickness for liquid cloud, ice, and snow

  • Cloud base height and top height

  • For liquid and ice variables, the total water path (liquid + ice + snow), effective radius, and optical thickness are calculated, where the totaled variables account for subgrid hydrometeors.

  • Accumulated GHI (in WRF v4.4+)



To activate this option, add the following record and parameter to namelist.input:

&diags
solar_diagnostics = 1
/

Note

If a tslist file is present, these variables are also written to the respective time series file(s).





Accumulated Physics Tendencies Output

This option outputs 16 accumulated physics tendencies for the following variables:

  • Potential temperature

  • Water vapor mixing ratio

  • U and V wind components



To activate this option, add the following parameter to namelist.input:

&physics
acc_phy_temd = 1




Miscellaneous Output Options

  • do_radar_ref=1 : Add to &physics to compute radar reflectivity unsing microphysics-specific parameters in the model. This option works with mp_physics= 2, 4, 6, 7, 8, 10, 14, 16, 17, 18, 19, 21, 24, 26, 28

  • prec_acc_dt=60 : Add to &physics to provide a time interval for outputting precipitation variables (rain from cumulus and microphysics schemes, and snow from microphysics), in minutes.






Using Multiple Lateral Boundary Condition Files

To speed up pre-processing of lateral boundary conditions in real-time forecasting, lateral boundary conditions can be split into multiple files, allowing a boundary condition file to be created as soon as the surrounding time periods become available, allowing the model to start sooner.


To activate this option, add the following parameters to namelist.input:

&time_control
bdy_inname = "wrfbdy_d<domain>_<date>"
multi_bdy_files = .true.

Note

Prior to WRFv4.2, this can only be done by adding -D_MULTI_BDY_FILES_ to ARCH_LOCAL in the configure.wrf file before compiling.



Output files are in the following format (for e.g., using a 6-hourly data interval):

wrfbdy_d01_2000-01-24_12:00:00
wrfbdy_d01_2000-01-24_18:00:00
wrfbdy_d01_2000-01-25_00:00:00
wrfbdy_d01_2000-01-25_06:00:00






Checking Output

Once WRF completes, the following may be useful for checking output:

  • If WRF was built with distributed memory (dmpar), an rsl.out.* and rsl.error.* file should exist - one of each for each processor used. Check for the print SUCCESS COMPLETE WRF at the end of any of these files to determine whether the simulation succeeded to completion. For e.g.,:

    tail rsl.out.0000

  • All namelist.input settings are preserved and written to a file named namelist.output.


  • Use the ncdump command to check the output times written to any netCDF file; for e.g.:

    ncdump -v Times wrfout_d01_yyyy-mm-dd_hh:00:00

  • See the wrf.exe output log (e.g., rsl.out.0000) for information on how long computations take for each model time step (time_step), how long it takes to write a WRF history/output or restart file; for e.g.:


    • Model Time Steps

      Timing for main: time 2006-01-21_23:55:00 on domain  2:    4.91110 elapsed seconds.
Timing for main: time 2006-01-21_23:56:00 on domain  2:    4.73350 elapsed seconds.
Timing for main: time 2006-01-21_23:57:00 on domain  2:    4.72360 elapsed seconds.
Timing for main: time 2006-01-21_23:57:00 on domain  1:   19.55880 elapsed seconds.

    • History File

      Timing for Writing wrfout_d02_2006-01-22_00:00:00 for domain 2: 1.17970 elapsed seconds.
Timing for main: time 2006-01-22_00:00:00 on domain 1: 27.66230 elapsed seconds.
Timing for Writing wrfout_d01_2006-01-22_00:00:00 for domain 1: 0.60250 elapsed seconds.