[ncl-talk] reading GRIB2 files

[Matt Flournoy]

Hi all,

Does anyone have experience reading RUC GRIB2 files? I'm trying to read
GRIB2 output from 13km RUC model data, which is available on the NOMADS
site (http://nomads.ncdc.noaa.gov/data.php#hires_weather_datasets).
Specifically, I am trying to read files from 06 July 2015, but I suspect
this problem is universal among at least all of the 13km RUC GRIB2 output
files.

I've tried a couple ways to read the GRIB2 data, including reading the
GRIB2 file and also trying to convert the GRIB2 file to netcdf. When I try
to read the GRIB2 data directly (specifically
"rap_130_20150706_0000_000.grb2"), I get the following warning message:

warning:getfilevarnames: rap_130_20150706_0000_000 contains no variables
readable by NCL

I've pasted my NCL script that yields this warning at the bottom of my
message.

Second, when I try to convert the GRIB2 file to netcdf using
"ncl_convert2nc" in the command line, I get this similar warning:

warning:getfilevarnames: rap_130_20150706_0000_000 contains no variables
readable by NCL
./rap_130_20150706_0000_000.grb2 contains no variables readable by NCL:
converting global attributes only

Then, when I "ncl_filedump" the created netcdf file, I get this:

Variable: f
Type: file
filename: rap_130_20150706_0000_000
path: rap_130_20150706_0000_000.nc
   file global attributes:
      creation_date : Fri Sep  4 09:52:47 CDT 2015
      NCL_Version : 6.2.1
      system : Linux bigbang.protect.nssl 2.6.32-504.12.2.el6.x86_64 #1 SMP
Sun Feb 1 12:14:02 EST 2015 x86_64 x86_64 x86_64 GNU/Linux
      Conventions : None
      grib_source : rap_130_20150706_0000_000.grb2
      title : NCL: convert-GRIB-to-netCDF
   dimensions:
   variables:

Do you know how to address this issue? I am currently using NCL version
6.2.1 on bigbang, and this problem also appears in other NCL versions.

Thank you,
Matt



------------ begin NCL script ---------------

;******************************************************************************;
; Load libraries.
;******************************************************************************;

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"

;-----------------------------------------------------------------------------;
; Synoptic overview plots of the July 06 2015 case from the RUC.
;-----------------------------------------------------------------------------;

begin

  ruc_filepath =
("/home/matt.flournoy/PECAN/overview/data/RUC_data/rap_130_20150706_0000_000.grb2")
  ruc_file     = addfile(ruc_filepath,"r")

  varnames = getfilevarnames(ruc_file)

  if(.not.any(ismissing(varnames))) then

    do i=0,dimsizes(varnames)-1

      printFileVarSummary(ruc_file,varnames(i))

    end do

  end if

end

--------------- end NCL script ----------------

-- 
Matthew Flournoy
M.S. Meteorology Candidate, University of Oklahoma
B.S. Meteorology, Penn State University
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