Re: meteogram from grib2 file

From: Luis Fernando Montana Roa <lfmontanar_at_nyahnyahspammersnyahnyah>
Date: Sat Sep 07 2013 - 06:57:51 MDT

Hi Mary,
Thank you for your suggestions. Another question: If each GRIB2 read file
has a single time step, ┐how can I create the time reference for the
meteogram?
Thanks

-- Fernando

On Fri, Sep 6, 2013 at 12:20 PM, Mary Haley <haley@ucar.edu> wrote:

> Hi Luis,
>
> Your script is one that assumes you have a WRF-ARW file. The GRIB2 file
> you attached doesn't have any file attribute information on it, so I'm not
> sure it is a proper WRF-ARW file.
>
> Usually, with WRF-ARW files, you have all kinds of file attributes, like
> MAP_PROJ, GRID_TYPE, DX, DY, TITLE, START_DATE, etc.
>
> Some of the wrf_user_xxxx functions depend on these global attributes in
> order to get the map projection information.
>
> You are trying to use "wrf_user_ll_to_ij", which depends on this attribute
> information, but can't find it.
>
> Also, you are trying read "Times" off the file, which doesn't exist on the
> file.
>
> Rule #1: Look at your data:
>
> ncl_filedump
> grid_WRF_20130904-060000_ECOLOMBIA_F00080000_Pideam_R4km.grb2
>
> This file does not have 2-dimensional lat/lon, but rather 1-dimensional
> lat/lon coordinate arrays. You shouldn't even need to use
> wrf_user_ll_to_jj. You can simply use lat/lon coordinate arrays:
>
> t2_point = t2({lat},{lon}) ; extract a time series at a point
> pres_point = pres({lat},{lon})
> tc_point = tc({lat},{lon})
> u_point = umet({lat},{lon})
> v_point = vmet({lat},{lon})
>
>
> However, the other issue is your "lon" value is not in the range of the
> longitude values on the file. They go from 0 to 360, and you are using a
> lon of -74.15. Add 360 to this, and it should work.
>
> lon = 285.85 ; -74.15 + 360
>
> This script still has issues, because you are referencing variables as if
> they are WRF ARW variables with "bottom_top" dimensions, which doesn't
> exist on this file. Therefore, this part of the script fails as well:
>
> ; Swap the dimensions as we want to plot time on the X axis later
> tt = tc_point(bottom_top|:,Time|:)
> ugrid = u_point(bottom_top|:,Time|:)
> vgrid = v_point(bottom_top|:,Time|:)
>
> I don't have time to try to get this code working, so please try to debug
> some of these issues yourself.
>
> You may want to consider using a "generic" meteogram code, instead of a
> WRF-ARW one. See the example at:
>
> http://www.ncl.ucar.edu/Applications/meteo.shtml
>
> --Mary
>
>
>
> On Sep 5, 2013, at 9:13 PM, Luis Fernando Montana Roa wrote:
>
> > Hi, I'm trying to plot a meteogram from GRIB2 files (such as attached).
> > When I run the script, shows the following errors:
> > ...
> > warning:Attempt to reference attribute (MAP_PROJ) which is undefined
> > warning:Attempt to reference attribute (TRUELAT1) which is undefined
> > warning:Attempt to reference attribute (TRUELAT2) which is undefined
> > warning:Attempt to reference attribute (STAND_LON) which is undefined
> > warning:Attempt to reference attribute (DX) which is undefined
> > warning:Attempt to reference attribute (DY) which is undefined
> > fatal:The result of the conditional expression yields a missing value.
> NCL can not determine branch, see ismissing function
> > fatal:["Execute.c":8128]:Execute: Error occurred at or near line 2262 in
> file $NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl
> >
> > fatal:["Execute.c":8128]:Execute: Error occurred at or near line 21 in
> file meteogram02.ncl
> >
> > Any suggestions?
> >
> > Thanks,
> >
> > -- Fernando
> >
> <meteogram02.ncl><grid_WRF_20130904-060000_ECOLOMBIA_F00080000_Pideam_R4km.grb2>_______________________________________________
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>

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Received on Sat Sep 7 06:58:04 2013

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