Help with WRF OBS-Nudging Process

[Naser]

Dear all,

Hello,

I am trying to run WRF OBS-Nudging and have followed the steps below:

1. I downloaded OBSGRID.exe from the following website:
   WRF Download
2. After compiling the code, I added my little-r files (OBS:YYYY-MM-DD_HH) to the OBSGRID directory. I also linked my met_em files to this directory.
3. I ran OBSGRID.exe. After the run, I obtained the following output files:
   • metoa_em.d01*
   • wrfsfdda_d01
   • OBS_DOMAIN1*
   • qc_obs_raw.d01.YYYY-MM-DD_HH:mm:ss.tttt
   • qc_obs_used.d01.YYYY-MM-DD_HH:mm:ss.tttt
   • plotobs_out.d01.YYYY-MM-DD_HH:mm:ss.tttt
4. I renamed metoa_em.d01* to met_em.d01* and moved them to my WRF directory. I then ran the WRF model with the attached namelist.input.

The model ran without any errors. However, I do not see any significant differences in temperature between the simulation applying OBS-Nudging and a normal run without it.

I suspect there might be an issue with either my steps or the preparation of the little-r files.

• If my method is correct, I may not have properly formatted the little-r files.
• If my method is incorrect, I would appreciate guidance to address this issue.

Additionally, I have a question:

• Is running OBSGRID.exe mandatory for applying FDDA OBS-Nudging?
• Can I directly place the little-r files in the WRF directory and use them for OBS-Nudging without running OBSGRID.exe?

I would greatly appreciate any assistance to overcome this problem.

Looking forward to your guidance.

Thank you,
Naser

 

[kwerner]

Hi Nasar,

It doesn't look like you're following the correct format to use obs-nudging. I'm attaching an old presentation that has some of the basic information and instructions for obs-nudging - see slide 37. Yes, you do need to run OBSGRID and then you should be using the OBSDOMAIN files, instead of the metoa files to run this.

Also see this section of the WRF Users' Guide - scroll down to the subsection "OBS_DOMAINdxx" which describes those files and their use.

 

[Naser]

Dear Kwerner
Hi,

Thank you for your answer.
I will let you know if I get a successful result.

Naser