Quick Grib2 Viewing with GrADS – 2

wave-height-with-colorbar

In the graphic above, I’ve added the cbar.gs script to enhance the display of the NDFD grib2 waveheight data, to show the color legend (right of the wave height graphic). To use a script in GrADS, you simply use the “run” command:

run cbar.gs

There are quite a few scripts to choose from, including the colorbar script at:

ftp://cola.gmu.edu/grads/scripts

NDFD data can be obtained from weather.noaa.gov.  It comes in two basic varieties.  The first type contains the first 3 days of the forecast, and is posted once each hour on the site.  The second type contains days 4 thru 7 of the forecast, and is posted 12 times per day.  NDFD is “National Digital Forecast Data”

I can look at incremented times in the grib2 forecast data, by the use of the following commands:

  • Set to time 2:    set t 2
  • Refresh output: d wvhgtsfc
  • Set to time 3:    set t 3
  • Refresh output:  d wvhgtsfc

Time two in this particular data set is three hours after time 1, and time 3 is three hours after time 2.   An animation script can be run to “animate” the change of the data throughout the time range.

The graphic at the top of the page displays the east coast of the U.S., and somewhat higher wave heights (red shaded) area just off the coast.

GrADS is a project that’s been kept at cola.gmu.edu and the Institute of Global Environment and Society (IGES). The Center for Ocean-Land-Atmosphere Studies (COLA) is the center within IGES where GrADS is developed and maintained. GrADS is GPLv2 licensed by its authors. The institution has nothing at all to do with this webpage or its author.

Screenshot license:


The screenshot at the top of the article is of a program that has been released under a free software license (GrADS, located at http://cola.gmu.edu and also at IGES). As a derivative work of that program, this screenshot falls under the same license. Details about the GrADS license are shown at the bottom of this page. Note that this webpage and its author have no connection whatsoever to the GrADS software, or its authors.

The Grid Analysis and Display System (GrADS) Version 2.0 carries a GNU General Public License (GPL version 2) as published by the Free Software Foundation. The link to the full text of the license:

http://cola.gmu.edu/grads/gadoc/COPYRIGHT

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