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[netCDFJava #QAX-163810]: Data Value Discrepancies Between Netcdf 4.2 and 4.3

Can you send me a file where you are seeing this problem (previous attachment 
didnt come through). thanks

> Hello John,
> Have you had a chance to inspect the RUC file I sent last week? Thanks,
> 
> Kevin
> 
> -----Original Message-----
> From: Unidata netCDF Java Support [mailto:address@hidden]
> Sent: Wednesday, January 22, 2014 5:58 PM
> To: Ray, Kevin M
> Cc: address@hidden
> Subject: [netCDFJava #QAX-163810]: Data Value Discrepancies Between Netcdf 
> 4.2 and 4.3
> 
> We do have a bug fix in version 4.4 about vertical levels sometimes getting 
> flipped. Can you send me a file where you are seeing this problem (previous 
> attachment didnt come through). Also, what version 4.3 are you using?
> 
> thanks,
> John
> 
> 
> 
> > John,
> > I was wondering if you had a chance to diagnose the RUC grib2 encoded file 
> > sent last week for data discrepancies when read using netcdf-java version 
> > 4.2 and 4.3.
> >
> > I was able to find and install the degrib command line utility provided 
> > publicly by the NWS. This provided an independent grib parser for comparing 
> > data values.
> >
> > Using the degrib output as a reference lead to the following conclusions:
> >
> > 1) If the provided RUC file is read using a 4.2 jar then the data values 
> > and variable names match those of the degrib output
> > 2) If the grib2 original RUC file is copied using the netcdf 4.3 Tools jar 
> > or the netcdfAll-4.3.jar then when read using a 4.2 or 4.3 jar
> > 2.a) Data values for the 3-D wind components 'flip' with respect to the 
> > altitude index
> > Ex: uWindComponentDegrib(alt=n, x=m, y=k) == 
> > uWindComponentNetcdfCopied(alt=n, x=m, y=k) => false
> > uWindComponentDegrib (alt=n, x=m, y=k) == uWindComponentNetcdfCopied 
> > (alt=50-n+1, x=m, y=k) => true
> > 2.b) Variable names change
> >
> > If you could please provide some insight as to whether these conclusions 
> > are plausible I would very much appreciate it. The degrib utility is 
> > independent of netcdf and its results indicate that the 4.2 jar is 
> > providing the correct data values, in contradiction to our discussion of 
> > 4.2/4.3 grib handling. I can provide additional data upon request, thanks
> >
> > Kevin
> >
> >
> > -----Original Message-----
> > From: Unidata netCDF Java Support [mailto:address@hidden]
> > Sent: Friday, January 17, 2014 10:32 AM
> > To: Ray, Kevin M
> > Cc: address@hidden
> > Subject: [netCDFJava #QAX-163810]: Data Value Discrepancies Between Netcdf 
> > 4.2 and 4.3
> >
> > Very likely!
> >
> > > John,
> > > I have found some projects that were utilizing a netcdf java 4.0 jar. 
> > > Would that version be subject to the same behavior we are discussing? 
> > > thanks,
> > >
> > > Sincerely
> > > Kevin
> > >
> > > -----Original Message-----
> > > From: Ray, Kevin M
> > > Sent: Thursday, January 16, 2014 12:43 PM
> > > To: 'address@hidden'
> > > Subject: RE: [netCDFJava #QAX-163810]: Data Value Discrepancies Between 
> > > Netcdf 4.2 and 4.3
> > >
> > > John,
> > > Here is a RUC file and associated gbx file for which data values were 
> > > found to differ. Please let me know if you require anything else,
> > >
> > > Kevin
> > >
> > > -----Original Message-----
> > > From: Unidata netCDF Java Support [mailto:address@hidden]
> > > Sent: Thursday, January 16, 2014 12:41 PM
> > > To: Ray, Kevin M
> > > Cc: address@hidden
> > > Subject: [netCDFJava #QAX-163810]: Data Value Discrepancies Between 
> > > Netcdf 4.2 and 4.3
> > >
> > > > John,
> > > > Thank you for getting back.
> > > >
> > > > I will take your advice and start the process of updating our 
> > > > netcdf-java dependencies to version 4.3.
> > > >
> > > > In the meantime would you mind examining a specific file to hopefully 
> > > > diagnose the nature of the discrepancies? I have been copying the file 
> > > > using custom java code (adhering to the previously referenced 
> > > > tutorials) and the netcdf tools UI jar (versions 4.2 and 4.3). My 
> > > > verification process has been bringing the file's data into MATLAB 
> > > > using the freely available nctoolbox. The data values brought into 
> > > > MATLAB were compared to the data values parsed by the custom java code 
> > > > by dumping data values into a csv file, and found to match in all 
> > > > instances. What did not match was the data values between original 
> > > > files and those that had been copied using a 4.3 netcdf jar.
> > > >
> > > > I'm afraid that I do not have immediate access to an independent 
> > > > verification process for the files under consideration, but I will look 
> > > > around and try to see if there is one available. In the meantime what 
> > > > would be the best way for me to get these files to you? Thanks!
> > >
> > > if too big for email, could use an ftp or web server or dropbox?
> > >
> > >
> > > Ticket Details
> > > ===================
> > > Ticket ID: QAX-163810
> > > Department: Support netCDF Java
> > > Priority: Normal
> > > Status: Open
> > >
> > >
> >
> >
> > Ticket Details
> > ===================
> > Ticket ID: QAX-163810
> > Department: Support netCDF Java
> > Priority: Normal
> > Status: Open
> >
> >
> 
> 
> Ticket Details
> ===================
> Ticket ID: QAX-163810
> Department: Support netCDF Java
> Priority: Normal
> Status: Open
> 
> 

Ticket Details
===================
Ticket ID: QAX-163810
Department: Support netCDF Java
Priority: Normal
Status: Open