1. Generating the Atmospheric input files¶

WRF Preprocessing System¶

The WRF Preprocessing System prepares the input files necessary for a WRF simulation. A few of the core functionalties of WPS include generating the simulation grid (domain), interpolating time-invariant terrestrial data to the simulation domain, interpolating time-varying meteorological data from other models onto the simulation domain 1 2.

We summarize the essential steps required to generate the initial and boundary conditions for the WRF model run. For a more comprehensive tutorial, please follow along with

WRF WPS Online Tutorial

1. Obtain and build WRF and WRF Preprocessing System (WPS) source¶

Download a bug-fixed version of the WRF and WPS v3.5.1 code from this link

Step 1: Extract the¶

Download the WRF V3 Static Geographic data from this link. Untar the archive and set the geog_data_path and geog_data_res in namelist.wps to the point to the directory containing the extracted geographic data and the resolution of this dataset respectively.
Specify the boundaries of the atmospheric domain, by setting the following quantities under geogrid in namelist.wps

dx dy Grid resolution in the x and y directions (in meters) e_we e_sn Velocity grid points in the west-east and south-north directions ref_lat ref_lon Real values specifying the latitude and longitude of a location whose (i,j) location in the simulation is known. map_proj Map projection (‘lambert’, ‘polar’, ‘mercator’, or ‘lat-lon.’) truelat1 First true latitude for the Lambert projection, or the true latitude for the polar and Mercator projections truelat2 Second true latitude for the Lambert projection stand_lon A real value specifying the longitude that is parallel with the y-axis in conic and azimuthal projections

Also see the namelist.wps best practices guide for more information.

To view the domain, use ncl util/plotgrids.ncl .. figure:: ../_images/WPS_plotgrid.png

scale

28 %

alt

RCESM schematic

align

center

An overall schematic of the Regional Community Earth System model architecture.

Run geogrid.exe

./geogrid.exe

When geogrid.exe completes successfully, it generates the files geo_em.d01.nc and **geogrid.log

Decide the initialiation time and the geographical domain, and download the appropriate real-time GRIB data. Some possible options are given in this page

Note that the NCAR Research Data Archive allows registered users to specify the geographical extents, select the time period, and download only the required fields.

Extract the downloaded grib files and run the script link_grib.sh with the path to this extracted data.

cat *.tar | tar xvf - -i
./link_grib.csh path_to_data

then create a symbolic link to the Vtable appropriate for the real-time data in use. For GFS, we can do .. code-block:: console

ln -sf ungrib/Variable_Tables/Vtable.GFS Vtable

In namelist.wps, set the start_date,**end_date**, interval_seconds under share and prefix under ungrib (to ‘GFS’).

#: Request sufficient memory on a compute node and run ungrib.exe

./ungrib.exe

This should have generated a file with prefix from start date to end date and at intervals specified. and check the generated inter

ncl util/plotfmt_nc.ncl GFS:2016-12-28_18
util/rd_intermediate GFS:2016-12-28_18

#: Run metgrid.exe

./metgrid.exe

#: Generate IC and BC files

cd ${WRF_ROOT}/test/em_real
ln -sf ../../../WPS_788/met_em.d01.201* .

Edit namelist.inp

./real.exe

modify namelist.inp https://esrl.noaa.gov/gsd/wrfportal/namelist_input_options.html

Replacing fields in wrfinput

https://wiki.uio.no/mn/geo/geoit/index.php/Replacing_fields_in_wrfinput

Common issues and their fixes¶

Issue #1:

ERROR: Could not open file METGRID.TBL

Fix: Set the opt_metgrid_tbl_path to ‘./’ or as appropriate

Issue #1:

Domain  1: Current date being processed: 2016-01-01_00:00:00.0000, which is loop #   1 out of 1465
configflags%julyr, %julday, %gmt:        2016           1   0.00000000
 metgrid input_wrf.F first_date_input = 2016-01-01_00:00:00
 metgrid input_wrf.F first_date_nml = 2016-01-01_00:00:00
-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE:  <stdin>  LINE:     851
 input_wrf.F: SIZE MISMATCH:  namelist ide,jde,num_metgrid_levels= 90  75  32 ; input data ide,jde,num_metgrid_levels=90 75 27
-------------------------------------------
-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE:  <stdin>  LINE:     851
 input_wrf.F: SIZE MISMATCH:  namelist ide,jde,num_metgrid_levels= 90  75  32 ; input data ide,jde,num_metgrid_levels=90 75 27
-------------------------------------------
 STOP wrf_abort

Fix: num_metgrid_levels in namelist.input

Issue #2:

-------------- FATAL CALLED ---------------
 FATAL CALLED FROM FILE:  <stdin>  LINE:     851
  input_wrf.F: SIZE MISMATCH:  namelist ide,jde,num_metgrid_levels= 90  75  32; input data ide,jde,num_metgrid_levels=90  75  27
 -------------------------------------------
 -------------- FATAL CALLED ---------------
 FATAL CALLED FROM FILE:  <stdin>  LINE:     851
  input_wrf.F: SIZE MISMATCH:  namelist ide,jde,num_metgrid_levels= 90  75  32; input data ide,jde,num_metgrid_levels=90  75  27
 -------------------------------------------
Note: The following floating-point exceptions are signalling: IEEE_OVERFLOW_FLAG
STOP wrf_abort

Fix: Upgrades to GFS on May 11, 2016. Moved from 27 vertical levels to 32.

https://www.perspectaweather.com/blog/2016/5/19/noaa-upgrades-its-primary-computer-forecast-model https://www.enviroware.com/how-to-deal-with-GFS-upgrades-when-running-WRF/

https://forum.wrfforum.com/viewtopic.php?f=6&t=9761 You can request customizable data and in the “Vertical Level(s):” you can select all fields, except: - all available ( obviously) - isobaric surface: 7 mbar - isobaric surface: 5 mbar - isobaric surface: 3 mbar - isobaric surface: 1 mbar

And submit a request.

This way, you will have your entire data base with 27 vertical levels.

Issue #3:

*************************************
d01 2014-05-12_00:00:00 *** Initializing nest domain # 2 from an input file. ***
-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE:  <stdin>  LINE:      70
program wrf: error opening wrfinput_d02 for reading ierr=          -8
-------------------------------------------

Fix: ./wrf.exe called before ./real.exe was called

1: Kelly Keene, The WRF Preprocessing System, COAWST Tutorial,2016 (pdf )
2: WRF ARW User Guide, Version 3, 2014 (pdf )

https://www.climatescience.org.au/sites/default/files/werner_data_utilities.pdf

http://www.mce2.org/11_aug_6_WRF_postprocessing%20%28Bruyere%29.pdf

http://wiki.cima.fcen.uba.ar/mediawiki/index.php/WRF