[Met_help] Re: MET -- grid conversion on GFS
John Halley Gotway
johnhg at rap.ucar.edu
Tue Feb 5 12:09:19 MST 2008
Luke,
I was able to get it to work. However, after looking at your data, I'd strongly recommend that you regrid the cmorph data to your WRF grid before running MODE.
Comparing a global dataset to a relatively small domain, you'll end up with MANY MANY objects in the global domain and relatively few in your smaller domain. And it'll take MODE way too long to
handle all of those objects. In the sample case I ran, I had 6 forecast objects and 133 observation objects!
Then I converted the cmorph data to the WRF grid, and ran MODE that way. However, there's a big problem. The copygb command which converts cmorph to the WRF grid runs fine but creates a field of all
zeros. By looking at the cmorph data, I see that it should contain non-zero values there, but for some reason it's all zeroed out. I have no idea why.
But here's the commands I ran:
// Convert WRF to cmorph domain
copygb -xg '255 0 1440 480 -59875 125 128 60125 125 250 250 64' WRFPRS_d01.96 WRFPRS_d01.96_cmorph_grid
// Run MODE on cmporph grid (takes about 4 minutes to run)
METv1.0/bin/mode WRFPRS_d01.96_cmorph_grid cmorph_3h_20070619_00z.grb WrfModeConfig_PRATE_cmorph_grid -outdir out_cmorph_grid
// Convert cmorph to WRF grid
copygb -xg '255 3 109 109 23688 37515 8 50000 24000 24000 0 64 36000 36000' cmorph_3h_20070619_00z.grb cmorph_3h_20070619_00z.grb_wrf_grid
// Run MODE on WRF grid (takes 2 seconds to run)
METv1.0/bin/mode WRFPRS_d01.96 cmorph_3h_20070619_00z.grb_wrf_grid WrfModeConfig_PRATE_wrf_grid -outdir out_wrf_grid
I've tarred up the relevant files and posted them to the ftp site:
ftp.rap.ucar.edu/incoming/irap/johnhg/for_luke.tar.gz
Good luck,
John
Luke Peffers wrote:
> Ok, you now have WRF forecast valid on June 19th, 2007 and cmorph
> precipitation rate data valid at the same time. Recall that I created the
> precip data using LATS from a flat binary dataset (that may be where a
> problem resides). If you'd like, I can ftp you the original binary data,
> otherwise, if you're interested here is the website for those data.
>
> http://www.cpc.ncep.noaa.gov/products/janowiak/cmorph_description.html
>
> Thank you
>
> Luke Peffers
> FSU Met.
>
> On Feb 5, 2008 12:00 PM, John Halley Gotway <johnhg at rap.ucar.edu> wrote:
>
>> Luke,
>>
>> Would you mind posting on of your forecast files (and the corresponding
>> obs) to the ftp site here at NCAR? I'd just like to play around with it to
>> see if I can figure it out. I imagine that we'll
>> continue getting copygb related questions through MET_HELP and this would
>> give me a chance to learn more about it.
>>
>> Thanks,
>> John
>>
>> Luke Peffers wrote:
>>> Thank you John:
>>>
>>> I have been using the template from the noaa site but just couldn't seem
>> to
>>> get the correct numbers to enter into it. I used the parameters that
>> you
>>> provided me on my WRF forecast data and when I try to view the new
>> copygb'd
>>> data, all variables are undefined. I think I will just work on this
>> problem
>>> for a while and see if I can figure out what I'm doing wrong. I'll let
>> you
>>> know what I find if you'd like.
>>>
>>> Thanks for all the help.
>>>
>>> Luke
>>>
>>> On Feb 4, 2008 6:26 PM, John Halley Gotway <johnhg at rap.ucar.edu> wrote:
>>>
>>>> Luke,
>>>>
>>>> There's an example listed on the copygb website for how to declare a
>>>> lat/lon grid:
>>>> http://www.cpc.ncep.noaa.gov/products/wesley/copygb.html
>>>>
>>>> Here's the template from the webiste:
>>>> grid='255 0 NX NY LAT0 LON0 128 LAT1 LON1 DX DY 64'
>>>> copygb -g"$grid" -x in.grb out.grb
>>>>
>>>> And I believe that this is what you should use:
>>>> grid='255 0 1440 480 -59875 125 128 60125 125 250 250 64'
>>>>
>>>> Let me know if that does the trick for you.
>>>>
>>>> John
>>>>
>>>> Luke Peffers wrote:
>>>>> Hello John:
>>>>>
>>>>> I ftp'd the grib file to you along with the .ctl and .gmp files just
>> in
>>>>> case. I can supply you with the original flat binary file I used to
>>>> create
>>>>> this grib file if you would like. As I said, I used LATS to create
>>>> these
>>>>> files. They work with GRADS well so I'm sure the grib format is
>>>> correct.
>>>>> Thanks for the help.
>>>>>
>>>>> Luke
>>>>>
>>>>> On Feb 4, 2008 4:01 PM, John Halley Gotway <johnhg at rap.ucar.edu>
>> wrote:
>>>>>> Luke,
>>>>>>
>>>>>> Unfortunately, that didn't have in it what I was hoping for.
>>>>>>
>>>>>> As for decoding the value in the dump of the grib file GDS section,
>>>> it's a
>>>>>> pretty difficult thing to do. If I remember correctly, I think we
>>>> actually
>>>>>> ran the Grib file through PCP-Combine to pull out
>>>>>> the grid definition, rather than through Grid-Stat. But the version
>> of
>>>>>> PCP-Combine you have only runs on grib code 61 (for APCP). I see
>> that
>>>>>> you're running on grib code 59 for precipitation rate.
>>>>>>
>>>>>> If you're grib data has 61 in it, you could run it through
>> PCP-Combine
>>>> and
>>>>>> look at the contents of the output NetCDF file to see the grid
>>>> definition.
>>>>>> If not, go ahead and send me one of your grib
>>>>>> files, and I'll figure out what the definition should be.
>>>>>>
>>>>>> John
>>>>>>
>>>>>> Luke Peffers wrote:
>>>>>>> Sure, here is the log file.
>>>>>>>
>>>>>>> Luke
>>>>>>>
>>>>>>> On Feb 4, 2008 2:58 PM, John Halley Gotway <johnhg at rap.ucar.edu>
>>>> wrote:
>>>>>>>> Luke,
>>>>>>>>
>>>>>>>> Do me a favor. Run Grid-Stat again using the command line option
>> "-v
>>>>>> 3"
>>>>>>>> and redirect the entire output to a log file. Then please send me
>>>> the
>>>>>> log
>>>>>>>> file.
>>>>>>>>
>>>>>>>> For example...
>>>>>>>> ./grid_stat fcst_file obs_file config_file -v 3 >& grid_stat.log
>>>>>>>>
>>>>>>>> There's another section of the output I'd like to see, and then I
>>>> think
>>>>>>>> it'll be pretty easy to help you.
>>>>>>>>
>>>>>>>> John
>>>>>>>>
>>>>>>>> Luke Peffers wrote:
>>>>>>>>> Hello John:
>>>>>>>>>
>>>>>>>>> I have been working on creating a precipitation dataset for MET
>>>>>>>> comparison.
>>>>>>>>> I was able to create convert a global satellite-derived
>>>> precipitation
>>>>>>>> set to
>>>>>>>>> GRIB1 format using LATS. I ran it through grid_stat in order to
>>>>>> extract
>>>>>>>> the
>>>>>>>>> grid information so I would be able to regrid my WRF forecast data
>>>> to
>>>>>>>> match
>>>>>>>>> the precip data grid. However, I can't seem to get copygb to work
>>>>>>>> correctly
>>>>>>>>> when I input my WRF forecast (i.e., all zero values). I recall
>> that
>>>>>> you
>>>>>>>>> were able to help me regrid my WRF to a GFS-like sub domain
>> through
>>>>>> the
>>>>>>>>> above mentioned method. I have attached the information for my
>>>> precip
>>>>>>>> data
>>>>>>>>> that was output from grid_stat below. Will you be able to help be
>>>> put
>>>>>>>>> together a copygb command that will take my WRF forecast and put
>> it
>>>> on
>>>>>> a
>>>>>>>>> grid similar to the precip data. Since the precip data is on a
>>>> large
>>>>>>>>> near-global domain, I think I will just use the plot_valid_flag
>>>> option
>>>>>>>> to
>>>>>>>>> zoom in instead of regridding my precip data as well. Please let
>> me
>>>>>> know
>>>>>>>> if
>>>>>>>>> I need to direct this question to another location.
>>>>>>>>>
>>>>>>>>> Thank you for your time.
>>>>>>>>> Luke Peffers
>>>>>>>>>
>>>>>>>>> Output from Grid_Stat:
>>>>>>>>>
>>>>>>>>> length: 32
>>>>>>>>> nv: 0
>>>>>>>>> pvpl: 255
>>>>>>>>> type: 0
>>>>>>>>> nx: 1440
>>>>>>>>> ny: 480
>>>>>>>>> lat1: 8448483
>>>>>>>>> lon1: 125
>>>>>>>>> res_flag: 128
>>>>>>>>> lat2: 59875
>>>>>>>>> lon2: 359875
>>>>>>>>> di: 250
>>>>>>>>> dj: 250
>>>>>>>>> scan_flag: 2
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Nov 1, 2007 3:29 PM, Luke Peffers <luke.peffers at gmail.com>
>> wrote:
>>>>>>>>>> Hello John:
>>>>>>>>>>
>>>>>>>>>> I am have some difficulty verifying my WRF model run with GFS
>>>> gridded
>>>>>>>>>> date. I would like to follow the general rule that when
>> comparing
>>>>>> two
>>>>>>>>>> gridded files, one should regrid the forecast file to the obs
>> grid,
>>>>>> in
>>>>>>>> my
>>>>>>>>>> case GFS. When I do that, mode compares my relatively small
>> domain
>>>>>> to
>>>>>>>> the
>>>>>>>>>> entire GFS (global) domain.
>>>>>>>>>>
>>>>>>>>>> I am, of course, running my WRF output through WRF Post
>> Processor.
>>>>>> I
>>>>>>>>>> regrid my files using COPYGB.
>>>>>>>>>>
>>>>>>>>>> I have no problem regridding the GFS data to my forecast grid
>>>> since
>>>>>> I
>>>>>>>>>> know the exact grid dimensions for the user defined grid from
>> WRF.
>>>> I
>>>>>>>> don't,
>>>>>>>>>> however, know the exact grid codes for a GFS-like grid that is of
>>>> the
>>>>>>>> exact
>>>>>>>>>> domain size of my forecast file. Thus, I continue to use MET with
>>>> obs
>>>>>>>> files
>>>>>>>>>> regridded to match my WRF output grid file.
>>>>>>>>>>
>>>>>>>>>> Do you know how I can resolve this problem?
>>>>>>>>>>
>>>>>>>>>> Thank you!!
>>>>>>>>>>
>>>>>>>>>> Luke Peffers
>>>>>>>>>> FSU Meteorology Department
>>>>>>>>>>
>>>>>>>>>>
>
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