WRF Output

WRF Output Fields

By default, WRF outputs numerous variables that are included in the wrf history files (wrfout*). However, there are options to remove some of the variables, to output additional variables, and to output certain variables to files other than the wrfout* files. Valid fields depend on the model options used, and fields with zero values are not computed by the model options selected. To see a full list of wrf output variables, issue the following command.

ncdump -h wrfout_d<domain>_<date>



Special WRF Output Variables

The WRF model outputs state variables (defined in the Registry/Registry.EM_COMMON file) that are used in the model’s prognostic equations. Some of these variables are perturbation fields; therefore the following definitions for reconstructing meteorological variables are necessary:


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
4 = Latitude and Longitude (including global)




Run-Time I/O Option

Input/output (IO) decisions (such as which variables to output, and which variables are associated with which stream) can be updated via the Registry files (found in the Registry directory), but making any changes to the Registry constitutes a cycle of “clean -a,” configure, and compile, which can sometimes be a lengthy process. The “run-time I/O” option allows these updates to be made at run-time, via the namelist.input file, by following these steps.

Note

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


  1. Create a text file (e.g., my_file_d0X.txt) for each domain in the directory where wrf.exe will be run. This/these file(s) define the output that will be modified. Contents of the file(s) associate a stream ID (for e.g., stream 0 is the default history and output) with a variable, and whether the field is added or removed. Following are a few examples.


    The following removes fields RAINC and RAINNC from the standard history file (stream 0 - wrfout_d0*).

    -:h:0:RAINC,RAINNC

    And the following adds the fields RAINC and RAINNC to an output stream 7, which creates a separate file from the wrfout_d0* files.

    -:h:7:RAINC,RAINNC

    Available options are:

    + or -

    add or remove a variable

    0-24

    which stream to use

    i or h

    input or history

    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

    Generally, using any other stream (except 1) is okay.



  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.

    When outputting variables to a new stream (i.e., not history stream 0), the following namelist variables should be added to the &time_control section. The settings can be modified as needed. For e.g., if you are adding 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 any spaces in between fields in the .txt file.

  • Variable names in the .txt file must be identical to the quoted string name from the Registry file (column 9)

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

  • Any field requested in the .txt file must already be declared as a state variable in the Registry.

  • ignore_iofields_warning namelist setting tells the program what to do if it encounters an error in the .txt file(s). The default is .true., which prints a warning message, but continues the run. If set to .false., the simulation aborts if there are errors in the .txt file(s).




Output Diagnostics


Time Series Output

Outputting time series data at particular locations within your domain can be useful for tracking the progression of particular variables.

To activate this option, a file called tslist must present in the WRF running directory. The tslist file contains a list of locations defined by their latitude and longitude, or i,j coordinates, along with a short description and abbreviation for each location. Create the tslist file following 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

If cell locations are to be used (e.g., for idealized cases), the i,j locations are to be specified as follows:

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


After wrf is run, for each location listed in tslist that exists inside the model domain (either coarse or nested), the following files are written:

pfx*.d0x.TS

the regular time series output of surface variables

pfx.d0x.UU

vertical profile of u wind component for each time step

pfx.d0x.VV

vertical profile of v wind component for each time step

pfx.d0x.WW

vertical profile of 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 specified prefix for the location in the tslist file

  • 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 component winds (default is false)

Note

Locations specified in the tslist file that do not exist in any domain are ignored by the time series capability.


See also

Additional information regarding this option can be found in the WRF/run/README.tslist file within the code.




Pressure Level Output

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

  • U and V wind speed

  • T (temperature)

  • Dewpoint temperature

  • Relative humididy (RH)

  • Geopotential Height


To activate this option, add the following to the &diags section of namelist.input. For e.g.,

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

The extra fields are output to auxiliary stream 23, and therefore the following should be set in &time_control in namelist.input. For e.g.,

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



Convective Storm Diagnostics

This option outputs the following extra fields in the history file (wrfout_d0*):

  • maximum 10 m wind speed

  • maximum helicity in 2 - 5 km layer

  • maximum vertical velocity in updraft and downdraft below 400 mb

  • mean vertical velocity in 2 - 5 km layer

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


To activate this option, add the following namelist settings:

&time_control
nwp_diagnostics = 1

&physics
do_radar_ref = 1



Climate Diagnostics

This option outputs 48 surface diagnostic variables. For T2, Q2, TSK, U10, V10, 10 m wind speed, RAINCV, RAINNCV, the following are calculated:

  • maximum and minimum

  • times when max and min occur

  • mean value

  • standard deviation of the mean


Output goes to auxiliary stream 3. To activate this option, add the following settings in &time_control in 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 the daily max and min, etc. are computed, it is advised to do a restart only at a multiple of auxhist3_intervals.




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 to &dynamics in namelist.input:

&dynamics
do_avgflx_em = 1

Additionally, if a Grell cumulus scheme is used, set the following in &dynamics in namelist.input to output time-averaged convective mass-fluxes:

&time_control
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 to namelist.input.

&afwa
afwa_diag_opt=1

And then set any of the following options to 1 in &afwa to output specific fields (set for each domain - default is 0=off).

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 in &afwa if afwa_ptype_opt=1:

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 “total” variables account for subgrid hydrometeors.

  • Accumulated GHI (since V4.4)



To activate this option, set the following in the &diags section of namelist.input:

&diags
solar_diagnostics = 1

Note

If tslist is also present, these same variables are 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 components of the wind



To activate this option, add the following to the &physics section of 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 scenarios, an option is available to create multiple lateral condition files. This allows a boundary condition file to be created as soon as the surrounding time periods become available, allowing the model to start the simulation sooner.

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

&time_control
bdy_inname = "wrfbdy_d<domain>_<date>"

&bdy_control
multi_bdy_files = .true.

Note

Prior to V4.2, this must be done through a compile option (adding -D_MULTI_BDY_FILES_ in ARCH_LOCAL in the configure.wrf file).



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 a model run completes, it is advised to quickly check a few things.

If WRF was built with distributed memory (dmpar), there should be an rsl.out.* and rsl.error.* file for each processor. If the simulation was successful, the message SUCCESS COMPLETE WRF should be printed at the end of these files. This can quickly be checked by typing

tail rsl.out.0000


All options in namelist.input are preserved to a filed named namelist.output.



To check the output times written to a netCDF file, the following netCDF command can be used (for example):

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


To see the time computations take for each model time step, the time it takes to write a history file, or a restart file, open the rsl.out.0000 file (or other standard-out files), which logs these times. For example:

  • 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.