WRFDA-4DVAR on nested domain

Any issues with the actual running of the WRF.

WRFDA-4DVAR on nested domain

Postby puneet336 » Wed Apr 03, 2019 11:55 am


I am trying to setup wrfda 4dvar simulation on 3km,1km nested domain setup for the first time using documentation available on internet. I have compiled WRFPLUS and WRFDA 3.9.1 and i was able to run the conus 60km single domain setup/tutorial succesfully, but, i am currently stuck at the first step as i am not sure about the input setup for WRFDA for nested domain.

AFAIK, we need following files for running wrfda -

a) First Guess
b) Observations ASCII/PREPBUFR
c) Background Error Statistics Binary

i ran a nested domain wrf simulation (3km,1km) for 6 days on 6 hourly data using following dataset
https://rda.ucar.edu/datasets/ds084.1/i ... g=20160310
for 2016/03/10 00:00:00 to 2016/03/17 00:00:00 and i have 114 wrfout files (wrfout_d01* + wrfout_d02*)
-> i have following "first guess" files - wrfbdy_d01 wrfinput_d01 wrfinput_d02

In conus 60km tutorial creates softlink to wrfinput_d01 as
Code: Select all
ln -sf wrfinput_d01  fg

but my simulation has nested domain setup. So, i am not sure which file (among wrfinput_d01 and wrfinput_d02) to use as fg

Observations - for 60 km setup, ob(01-07).ascii files are used as input
Code: Select all
$DAT_DIR/ob/2008020512/ob01.ascii  (obs_gts_2008-02-05_12:00:00.4DVAR)
$DAT_DIR/ob/2008020513/ob02.ascii  (obs_gts_2008-02-05_13:00:00.4DVAR)
$DAT_DIR/ob/2008020514/ob03.ascii  (obs_gts_2008-02-05_14:00:00.4DVAR)
$DAT_DIR/ob/2008020515/ob04.ascii    ...

and from conus 60km setup it seems that following are input for obsvar.exe -
Code: Select all
 gdas1.t12z.1bamub.tm00.bufr_d ,gdas1.t12z.1bamua.tm00.bufr_d, obs.2008020512, gdas1.t12z.prepbufr.nr

1. (INPUT) For running obsproc.exe we need following -
A namelist file - available at $WRFDA_DIR/var/obsproc/namelist.obsproc.4dvar.wrfvar-tut
observation error file - can we reuse $WRFDA_DIR/var/obsproc/obserr.txt for my experiment? or need to generate this afresh?
One or more observation files - from where to get/download observation files for my experiment year (2016) ?
msfc.tbl - as i am running for Asian region , do i need to add this ?

2. (OUTPUT) Is it correct that the setup (or output of obsvar.exe) in my case (for 7 days) should be arranged as following for wrfda.exe ? -
Code: Select all

also, obsvar.exe will generate obs_gts_2016-03-10_00:00:00.4DVAR .. obs_gts_2016-03-17_00:00:00.4DVAR files in same directory ? and i have to create directory structure or obsvar.exe will take care about it?

I understand that there are too many queries in this post - you could guide me on "downloading observation files" and setting up the obsvars.exe first.

Any help/hint would be useful - for me & other beginners like me.
Posts: 10
Joined: Thu Mar 22, 2018 2:02 am

Re: WRFDA-4DVAR on nested domain

Postby batarabagus » Sat Apr 27, 2019 7:36 am

Im also a beginner in DA 4DVAR,
But, based on what i have read from several sources, 4dvar doesn't support nested domain, so if you want to use the highest resolution domain (e.g wrfinput_d04), you can use one way nesting (ndown.exe) to create boundary for fourth-domain. After that, the fourth-domain can be run individually just like domain without nesting and for input DA 4dvar.
Posts: 1
Joined: Sat Jan 26, 2019 8:30 am

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