[gradsusr] Displaying GOES-R data in GRADS?

[Jennifer M Adams]

Hi, Bob —
There are two possible ways to attack this problem:
1. Rewrite the data as station data, where each pixel is a station report
2. Interpolate the satellite projected data to a regular lat/lon grid.

The station data option is probably easier to code, but will significantly expand the data volume and your display options will be more limited. The interpolation could be done entirely outside of GrADS with customized code, or you could use a PDEF file, which can be a little tricky to create. I have had success using the ESMF_RegridWeightGen tool, which takes as input grid information for the source and destination grids and outputs the interpolation weights. I wrote a short C program (which I can share with you, if you want it) to convert the interpolation weights delivered by RegridWeightGen into a PDEF file. It may be a bit of a nuisance to prepare the inputs to the RegridWeightGen tool — that tool was designed for irregular model grids, not satellite data, but I think it is flexible enough to manage the job. ESMF’s user support is excellent. There may be other tools specifically designed for GOES-16 data that could be used to manipulate the data to transform it into something GrADS could handle. Is the lat/lon data for the satellite projection is the same for every image?
—Jennifer


On Feb 21, 2017, at 10:23 PM, rabin at ssec.wisc.edu<mailto:rabin at ssec.wisc.edu> wrote:

Hello,

I am interested in plotting GOES-16 (GOES-R) data in GRADS.
The data are available as netCDF-4 files. I am able to display
radiance from a test file (model simulated),
but will need to define the navigation in order to
correctly map the image. The netCDF-4 file doesn't include
lat/lon variables. It contains meta data needed to define the
satellite projection.
An array of lat/lon values can be computed for each grid point using
equations supplied in the GOES-R documentation.
My question is how to assign those arrays after opening the netCDF file
with "sdfopen". Can PDEF could be used to read in a file
with an array of lat/lon values? This wasn't clear to me from the
GRADS documentation. If so, what would
be the preferred options for using PDEF? For example, would one of these
option work?

PDEF isize jsize BILIN format byteorder fname
PDEF isize jsize GENERAL num format byteorder fname
PDEF isize jsize FILE num format byteorder fname

Thanks! -Bob Rabin


Thanks, -Bob


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--
Jennifer Miletta Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
George Mason University



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