[Wrf-users] OBS nudging

Bart Brashers bbrashers at Environcorp.com
Wed Aug 24 18:09:27 MDT 2011


I have a few questions about using OBS nudging in WRF v3.3.  I'm using
the 12km NAM data, which comes in 6 hour intervals.  WPS ran fine, and I
have met_em files every 6 hours.

 

I have processed MADIS data to little_r format, and named the files
OBS:YYYY-MM-DD_HH.  Each file contains 6 hours of data, which I've
confirmed via grep (e.g. "grep 200801 OBS:2008-01-29_18 | cut -c 327-336
| sort | uniq" shows the right time-stamps).

 

1. OBSGRID.EXE creates OBS_DOMAIN101, OBSDOMAIN102, etc.  But each file
contains only ONE hour's data (the analysis hour +/- 30 minutes).  The
OBS data for the next 5 hours is not output.  How can I get OBSGRID.EXE
to create OBS_DOMAIN1* files that contain ALL the available data?  I
want to nudge every hour, not every 6 hours.

 

2. The most recent notes in the WRF User's Guide
<http://www.mmm.ucar.edu/wrf/users/wrfv3.1/How_to_run_obs_fdda.html>
make no mention having to concatenate the OBS_DOMAIN1* output from
OBSGRID.EXE to OBS_DOMAIN101, but the tutorial notes
<http://www.mmm.ucar.edu/wrf/OnLineTutorial/Class/cases/obs_nudging1.php
>  do say so.  Which is correct?  Will WRF not read OBS_DOMAIN102,
OBS_DOMAIN103, etc.?

 

3. If I want to nudge every hour, do I set auxinput11_interval_m = 60 in
WRF's namelist?  Or is that supposed to match OBSGRID's record1 interval
?

 

4. If I want to keep nudging till the very end of my simulation, can I
set auxinput11_end_h = 99999?  

 

The meaning of these two values is pretty unclear in the
README.namelist, README.obs_fdda, as well as the WRF User's Guide and
tutorial notes.  If anyone can shed some light, I'd be most
appreciative.

 

Thanks,

 

Bart

 



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