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Radiance data assimilation

Reference: Download the tutorial presentation

Source code

Get the pre-compiled code, if you have not done so.

WRFDA/var/build/da_wrfvar.exe_3dvar is the executable that will be used in this session.

Choice of your working directory

We recommend running each session in a separate directory, so that it will be easier to check for the necessary input files and look for what output files are created after a successful run.

We recommend you create /data1/${USER}/DA/radiance and cd there to be your working directory for this session.

Input files

The radiance case is the same CONUS60 case you have used in obsproc, running WRFDA-3DVAR and gen_be sessions.

The procedure is the same as Running WRFDA-3DVAR except for some more extra input files and namelist.input settings.

In addition to the basic input files (LANDUSE.TBL, fg, ob.ascii, be.dat) that you should have been familiar with by now, the following extra files are required for radiances:

  • Radiance data in NCEP BUFR format

cd /data1/${USER}/DA/radiance

ln -fs /wrfhelp/DATA/WRFDA/CONUS60/ob/2008020512/gdas1.t12z.1bamua.tm00.bufr_d.linux ./amsua.bufr
ln -fs /wrfhelp/DATA/WRFDA/CONUS60/ob/2008020512/gdas1.t12z.1bamub.tm00.bufr_d.linux ./amsub.bufr

  • radiance_info files (one instrument a file, under radiance_info directory)

ln -fs ${your_source_code_dir}/WRFDA/var/run/radiance_info ./radiance_info # radiance_info is a directory

  • VARBC.in

ln -fs ${your_source_code_dir}/WRFDA/var/run/VARBC.in ./VARBC.in

  • Radiative Transfer Model (CRTM or RTTOV) coefficient files

(CRTM only) ln -fs ${your_source_code_dir}/WRFDA/var/run/crtm_coeffs ./crtm_coeffs # crtm_coeffs is a directory

(RTTOV only) ln -fs /wrfhelp/WRFDA/external/rttov10/rtcoef_rttov10/rttov7pred51L ./rttov_coeffs # rttov_coeffs is a directory

Edit namelist.input

A sample namelist.input is provided in the WRFDA package as WRFDA/var/test/radiance/namelist.input

cp ${your_source_code_dir}/WRFDA/var/test/radiance/namelist.input ./namelist.input

vi namelist.input (pay special attention to the following radiance-related settings)

&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.
varbc_nbgerr = 5000
/
&wrfvar21
time_window_min = "2008-02-05_11:00:00"
/
&wrfvar22
time_window_max = "2008-02-05_13:00:00"
/

Run WRFDA

mpirun -np 4 -machinefile ~/mach ${your_source_code_dir}/WRFDA/var/build/da_wrfvar.exe_3dvar

Check output

Check analysis increments.

Check statistics.

There are extra diagnostic files when assimilating radiance data.
01_qcstat_*amsu*
01_oma_*amsu*
VARBC.out

Graphics

/wrfhelp/SOURCE_CODE/WRFDA/var/scripts/da_rad_diags.ksh
Note: This version of da_rad_diag.ksh is customized to work for the directory structures for this tutorial. For your own applications, you should read through the default da_rad_diags.ksh and make proper changes.

The diagnostics netCDF files will be created in the /data1/$USER/DA/radiance/diags directory.

Other practice

  • Try linking /wrfhelp/DATA/WRFDA/CONUS60/ob/2008020512/gdas1.t12z.1bamua.tm00.bufr_d as amsua.bufr in your working directory and run WRFDA to see what log messages you will get.

Advanced

  • Try changing some of the namelist.input settings (for example, different instruments and sensors, different Radiative Transfer Model) and compare the results.

 


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