Data Extraction from NWP models

From: <Waylon.Collins_at_nyahnyahspammersnyahnyah>
Date: Tue, 07 Aug 2007 10:48:04 -0500

Dear List,


My first goal is to locate command-line software (no GUIs) that will allow me to (1) input GRIB files containing archived WRF-NMM, Eta, and RUC numerical weather prediction (NWP) model forecast output, and latitude/longitude values for a particular point, then (2) output the interpolated values for selected variables at that latitude/longitude point, in a manner that is faster than my current method. My current method is to use Arthur Taylor's degrib program ( In particular, I have run degrib from within a Perl script which extracts selected output from Eta/WRF-NMM GRIB files. However, my data set is several years long and it takes 1 week to process 1 year of data -- too slow! My programming experience is limited to shell scripting. I have some experience with NCL, but not with extracting data from numerical models. Has anyone written an NCL script to perform the foregoing t asks?


My second goal is to calculate certain thermodynamic parameters (at specific latitude/longitude points) not available in the aforementioned GRIB files. The parameters are (1) Equilibrium Level (EL) height, (2) EL temperature, and (3) CAPE in the -10C to -20C layer. To clarify, the source data are Eta, WRF-NMM, and RUC GRIB files containing NWP forecast output, not "sounding" data. Does anyone have an NCL script to perform these tasks?


Dennis Shea provided helpful comments to me on 17 August 2005 relating to the inability to use NCL's uv2dv_cfd function with the Eta and WRF (NMM/ARW??) NWP models. Hopefully, I can use NCL to simply extract interpolated values (from selected variables) at specific latitude/longitude points from NWP model data written to GRIB files. On 12 April 2007, Mary Haley mentioned Fortran code to perform some of the thermodynamic parameters. However, I need to extract EL height and temperature, and CAPE for specific layers, from NWP output, not a "sounding".





Waylon Collins (Senior Forecaster)
NOAA/National Weather Service
300 Pinson Drive
Corpus Christi, TX 78406
(United States)
Telephone: (361) 289-0959           

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