grib to netcdf conversion

From: Kirby, Stephen (Civ, ARL/CISD) <sfkirby_at_nyahnyahspammersnyahnyah>
Date: Wed, 15 Mar 2006 10:15:49 -0700

Hello Dennis et. al.,
 
About 6 months back, you wrote a NCL script for me (which I greatly
appreciate!!) to convert GRIB data (RUC weather model output) to netCDF.
I'm using the resultant netCDF file as input to the "LAPS" data
assimilation model. I thought all was ok till taking a closer look at
the logs.
 
They indicated that LAPS was not finding height and temperature data
among others. I then compared the sample RUC netCDF file from the LAPS
home page against the RUC netCDF created from your script Dennis, and
saw that the parameter names differ, some of the attributes differ, and
I'm not getting all of the parameters seen in the sample netCDF from the
LAPS site.
 
==============(1) For ex., the parameters it can't translate:
======================================================
 
warning:NclGRIB: Unknown grib parameter number detected (170), using
default variable name (VAR_170)
warning:NclGRIB: Unknown grib parameter number detected (178), using
default variable name (VAR_178)
warning:NclGRIB: Unknown grib parameter number detected (171), using
default variable name (VAR_171)
warning:NclGRIB: Unknown grib parameter number detected (179), using
default variable name (VAR_179)
warning:NclGRIB: Unknown grib parameter number detected (198), using
default variable name (VAR_198)
warning:NclGRIB: Unknown grib parameter number detected (186), using
default variable name (VAR_186)
warning:NclGRIB: Unknown grib parameter number detected (187), using
default variable name (VAR_187)
warning:NclGRIB: Unknown grib parameter number detected (188), using
default variable name (VAR_188)
 
Is there a way to extract these from the GRIB? Is an updated GRIB (or
NCL) table needed?
 
===========(2) How can I go about renaming a parameter and altering
(some of the) attributes, for ex., need to go======================
 
from:

float HGT_236_HYBL(z, x, y) ;

                HGT_236_HYBL:center = "US Weather Service - National
Met. Center" ;

                HGT_236_HYBL:long_name = "Geopotential height" ;

                HGT_236_HYBL:units = "gpm" ;

                HGT_236_HYBL:_FillValue = -999.f ;

                HGT_236_HYBL:level_indicator = 109 ;

                HGT_236_HYBL:grid_number = 236 ;

                HGT_236_HYBL:parameter_number = 7 ;

                HGT_236_HYBL:forecast_time = 0 ;

                HGT_236_HYBL:initial_time = "03/08/2006 (00:00)" ;

 

to:

float hgt(record, z, y, x) ;

                hgt:long_name = "geopotential height" ;

                hgt:units = "gp m" ;

                hgt:z = "z_dim" ;

                hgt:record = "reftime, valtime" ;

                hgt:valid_range = -1000.f, 50000.f ;

                hgt:_FillValue = -9999.f ;

                hgt:navigation_var = "nav" ;

                hgt:nimbus_name = "GH" ;

                hgt:nimbus_level = "Hybrid" ;

 

although I don't see a reftime or valtime parameter in my translated
netCDF so don't know how to insert a "record" dimension.

 

For reference Dennis, I'll attach the NCL script you created for me.

 

TIA,

 

Steve

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Received on Wed Mar 15 2006 - 10:15:49 MST

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