NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.

To learn about what's going on, see About the Archive Site.

Re: [idvusers] Problem with plotting thermal wind vectors from GRIB2 files

  • To: "Kevin R. Tyle" <ktyle@xxxxxxxxxxxxxxxx>
  • Subject: Re: [idvusers] Problem with plotting thermal wind vectors from GRIB2 files
  • From: Don Murray <don.murray@xxxxxxxx>
  • Date: Fri, 03 Feb 2012 10:14:30 -0700
The problem is that for grib2 data, the pressure levels are in Pascals, so you need to use 50000 and 10000.
GEMPAK always stores levels to hPa - the benefit of having a known vocabulary, but then again, you have to convert to GEMPAK format. ;-) 

Don

On 2/3/12 9:52 AM, Kevin R. Tyle wrote:

Hi all,

I set up a formula in IDV to plot thermal wind vectors, a la:
<derived description="thermal wind in a layer"
formula="thrm(F1,user_Top_of_Layer[default=500],user_Bottom_of_Layer
[default=1000])" id="thermalWind" isdefault="false" isenduser="true">

Whenever I do this on a GRIB2 format grid file, e.g. realtime NAM or GFS
from the motherlode or atm-nsf opendap servers, I end up with all
missing data when I load in the formula, specify my levels, and choose
the 3D geopotential height from the GRIB2 file.

If I do the same on the same model data that has been converted to
GEMPAK, and also with the sample model data used in the IDV Workshop
(which I believe is GRIB1), the thermal wind vectors plot fine.

I suspect there is some issue specifically related to GRIB2 format here ...

Thanks for looking into this!

--Kevin

_____________________________________________
Kevin Tyle, Systems Administrator
Dept. of Atmospheric & Environmental Sciences
University at Albany
Earth Science 235, 1400 Washington Avenue
Albany, NY 12222
Email: ktyle@xxxxxxxxxx
Phone: 518-442-4578
_____________________________________________

_______________________________________________
idvusers mailing list
idvusers@xxxxxxxxxxxxxxxx
For list information, to unsubscribe, visit:
http://www.unidata.ucar.edu/mailing_lists/


--
Don Murray
NOAA/ESRL/PSD and CIRES
303-497-3596
http://www.esrl.noaa.gov/psd/people/don.murray/