Reference
The goal of this session is to generate the observation input (i.e. the y0 and R shown in the WRFDA flowchart) to WRF-Var.
Note: OBSPROC is not necessary, if you intend to assimilation conventional data in Prepbufr format. The real-time Prepbufr formated conventional data can be downloaded for free from NCEP ftp sites.
However, should you have some observational data from non-conventional observational network, such as high-frequent automatical weather station (AWS), intensified surface and atmospheric observations etc. you have to convert your own data to little_r format and process with OBSPROC.
WRFDA DOES NOT support use Prepbufr format and little_r format observation data at the same time.
Source code
We recommend running with pre-compiled code, so that you can save some compilation time.
Copy the pre-compiled code to your code directory, if you have not done so.
/scratch01/tutuser00/2011WRF_tutorial/WRFDAV3/var/obsproc/obsproc.exe 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 ~tutuser##/obsproc directory and enter this directory to be your working directory for this session.
Input data
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observations in little_r format
The first step of observation preprocessing is to prepare observations in little_r format.
For this tutorial, an observation file in little_r format is provided.
For your other applications, you will have to prepare your own observations.
> ln -fs /scratch01/tutuser00/DA_Input_Data/nari/ob/2007091500/obs.2007091500 obs.2007091500
/scratch01/tutuser00/DA_Input_Data/nari/ob/2007091500/obs.2007091500 is the observation file in little_r format.
It is a text file. You can edit it to see
what is in it.
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external observation error table
The external observation error file (obserr.txt) is provided in the WRFDA package under var/obsproc directory.
Make sure it is present in your obsproc working directory.
> ln -fs /scratch01/tutuser00/2011WRF_tutorial/WRFDAV3/var/obsproc/obserr.txt obserr.txt
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namelist.obsproc
For your reference, an example namelist (namelist.obsproc.3dvar.wrfvar-tut) has been included in the WRFDA package under var/obsproc directory.
Copy and rename the namelist to be namelist.obsproc under your working directory.
> cp /scratch01/tutuser00/2011WRF_tutorial/WRFDAV3/var/obsproc/namelist.obsproc.3dvar.wrfvar-tut namelist.obsproc
Edit namelist.obsproc to configure the little_r observation file location, domain, time window, etc. (Hint: use "ncdump -h /scratch01/tutuser00/DA_Input_Data/nari/rc/2007091500/wrfinput_d01" to get the header information)
** If you don't know how to modify the namelist.obsproc to fit this case, see namelist
Run obsproc (obsproc.exe)
> ln -fs /scratch01/tutuser00/2011WRF_tutorial/WRFDAV3/var/obsproc/obsproc.exe
>./obsproc.exe
** Don't know if you are successful ? see the reference log file
Check output
obs_gts_2007-09-15_00:00:00.3DVAR is the main output.
Edit obs_gts_2007-09-15_00:00:00.3DVAR to check its content.
*.diag are diagnostic files.
HEIGHT/PRES/RH/TEMP/WIND.txt are observation errors in plain-text format for easy reference.
Graphics
Use NCL script, provided as /scratch01/tutuser00/2011WRF_tutorial/WRFDAV3/var/graphics/ncl/plot_ob_ascii_loc.ncl , to see the locations of observations contained in obs_gts_2007-09-15_00:00:00.3DVAR
>cp/scratch01/tutuser00/2011WRF_tutorial/WRFDAV3/var/graphics/ncl/plot_ob_ascii_loc.ncl plot_ob_ascii_loc.ncl
Please changes the beginning of plot_ob_ascii_loc.ncl
... ...
date = "2007091500"
obfile = "obs_gts_2007-09-15_00:00:00.3DVAR"
fgfile = "/scratch01/tutuser00/DA_Input_Data/nari/rc/2007091500/wrfinput_d01" ; for retrieving mapping info
out_type = "pdf"
... ...
>ncl plot_ob_ascii_loc.ncl
>evince obsloc2007091500.pdf
If this was successful, you can continue to try another session.
