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[netCDFJava #NBT-844482]: problems with add_offset, scale

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  • Subject: [netCDFJava #NBT-844482]: problems with add_offset, scale
  • Date: Tue, 02 Aug 2016 13:04:16 -0600
Heather,

Now that I think about it, the raw data in a Level 2 file are unsigned bytes, 
so you shouldn't even be able to get a value of -24.
If I convert -24 to its unsigned byte equivalent, 232, then the scale and 
offset give me 0.975. 

What are you using to read the data back in? Are you converting to a netCDF 
version 3 file or a version 4 file? The version matters, because
netCDF 3 doesn't support unsigned data, so we set an attribute _Unsigned to 
indicate that the data are unsigned; the data type netcdf variable
itself is byte. For netcdf version 4, the data are written as unsigned bytes.

Writing out netcdf version 4 files from netcdf-java requires having the 
netcdf-C library installed and configured, so I'm going to guess you're writing
netcdf version 3 files.

Ryan

> A RhoHV that low wouldn't even be observed with tornado debris.  It's not
> reasonable.  I've checked against another conversion tool and it says the
> RhoHV value at the grid point is 0.975.
> 
> At another grid point, unidata's conversion tool says RhoHV is -125 (before
> the correction, -0.215 after) and the other tool says 0.638333.
> 
> At yet a third grid point, unidata = 50 before and 0.36833335, a value
> which the other tool agrees with.
> 
> I don't know what is going on, but something isn't right in the unidata
> converter.


Ticket Details
===================
Ticket ID: NBT-844482
Department: Support netCDF Java
Priority: Normal
Status: Closed
===================
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