=============================================================================
Before proceeding, please read README.basics first to get some basic ideas on 
running WRFDA with conventional data.
Then, if you are interested in radiance data assimilation, please read through
this README.radiance to learn more on the settings and extra input files 
required for radiance data assimilation.
Please see also Chapter 6 of WRF ARW User's Guide for more details.

RTM (Radiative Transfer Model) that can be used in WRFDA:
  CRTM REL-2.3.0
  RTTOV v12.1
=============================================================================

Setup and Run - with radiance data

1. Input files:

In addition to the basic input files (LANDUSE.TBL, fg, ob.ascii, be.dat) mentioned
in README.basics, the following extra files are required for radiance:
  radiance data in NCEP BUFR format, radiance_info files, VARBC.in,
  RTM (CRTM or RTTOV) coefficient files (see "Notes on coefficients" below).

  ln -sf ${DAT_DIR}/gdas1.t00z.1bamua.tm00.bufr_d  ./amsua.bufr
  ln -sf ${DAT_DIR}/gdas1.t00z.1bamub.tm00.bufr_d  ./amsub.bufr
  ln -sf WRFDA/var/run/radiance_info    ./radiance_info  # radiance_info is a directory
  ln -sf WRFDA/var/run/VARBC.in         ./VARBC.in
  (CRTM only)
     Either ln -sf WRFDA/var/run/crtm_coeffs_2.3.0 ./crtm_coeffs  # crtm_coeffs is a directory
     or set namelist variable crtm_coef_path to the location of coef files
        crtm_coef_path='/user/WRFDA/var/run/crtm_coeffs_2.3.0'
  (RTTOV only) ln -sf rttov10/rtcoef_rttov10/rttov7pred51L ./rttov_coeffs  # rttov_coeffs is a directory

2. namelist.input

Pay special attention to &wrfvar4, &wrfvar14, &wrfvar21, and &wrfvar22
See WRFDA/var/README.namelist for namelist descriptions.

&wrfvar4
 use_amsuaobs=true
 use_amsubobs=true
/
&wrfvar14
 rtminit_nsensor=6,
 rtminit_platform=1,1,1,1,1,1,
 rtminit_satid=15,16,18,15,16,17,
 rtminit_sensor=3,3,3,4,4,4,
 thinning_mesh=120.0,120.0,120.0,120.0,120.0,120.0,
 thinning=true,
 qc_rad=true,
 write_iv_rad_ascii=false,
 write_oa_rad_ascii=true,
 rtm_option=2,
 only_sea_rad=false,
 use_varbc=true,
 use_crtm_kmatrix=true,
 use_rttov_kmatrix=true,
 crtm_coef_path='./crtm_coeffs'
 crtm_mwwater_coef='FASTEM5.MWwater.EmisCoeff.bin'
 crtm_irwater_coef='Nalli.IRwater.EmisCoeff.bin'
 crtm_irland_coef='USGS.IRland.EmisCoeff.bin'
 rttov_emis_atlas_ir=0,
 rttov_emis_atlas_mw=0,
/
&wrfvar21
time_window_min="2008-02-05_10:30:00.0000",
/
&wrfvar22
time_window_max="2008-02-05_13:30:00.0000",
/

3. Notes on coefficients

(1) for CRTM

Starting with V4.0, CRTM coefficient files are NOT included in any of the
WRF or WRFDA tar files. There are two ways to get this data.
1. Users need to download their required subset of CRTM coefficient files 
from this web page:
http://www2.mmm.ucar.edu/wrf/users/wrfda/download/crtm_coeffs.html
2. The full set of CRTM coefficients may be downloaded from:
ftp://ftp.emc.ncep.noaa.gov/jcsda/CRTM/REL-2.3.0/crtm_v2.3.0.tar.gz

Prior to  V4.0, the subset of CRTM coefficient files were included in the 
WRFDA tar file in the WRFDA/var/run/crtm_coeffs_2.2.3 directory (please see 
also WRFDA/var/run/README).

After unzip/untar crtm_v2.3.0.tar.gz, you will find all the coefficient files
under the directory fix. You will need to create another directory to copy or link 
the files that will be used in WRFDA. Please see also the CRTM user guide
ftp://ftp.emc.ncep.noaa.gov/jcsda/CRTM/CRTM_User_Guide.pdf
for the options of proper coefficient files for your applications.

(2) for RTTOV

Please visit http://research.metoffice.gov.uk/research/interproj/nwpsaf/rtm
for the RTTOV information.
The RTTOV coefficient files that come with the RTTOV source code or that are 
downloaded separately are placed in different sub-directories.
To run WRFDA, the coefficient files to be used should all be under the 
rttov_coeffs sub-directory in the WRFDA working directory.
For most basic applications, the coefficient files available in the RTTOV source 
code rttov11/rtcoef_rttov11/rttov7pred51L would be sufficient.