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[netCDF #QTC-832048]: NetCDF4.2 trouble reading data with strides from aggregated data.

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  • Subject: [netCDF #QTC-832048]: NetCDF4.2 trouble reading data with strides from aggregated data.
  • Date: Tue, 14 Aug 2012 15:12:57 -0600
Ansley-
There are two issues.
First, there is your stride problem.
I have a fix and am testing it now.

Second, and unconnected to the stride problem.
There is an issue with how ferret
handles projections on grids.
[I should note that corresponding requests
on TDS give similar problematic results]

Consider the following url with constraint:
http://cwcgom.aoml.noaa.gov/thredds/dodsC/AVHRRSST/SST.nc.dds?sst.sst
If I put this in a browser, I get back this:
Dataset {
    Float32 sst[time = 133][y = 2951][x = 3657];
} AVHRRSST/SST.nc;

However, the DAP2 spec was changed a couple of years ago
so that the correct result should be this:
Dataset {
Structure {
    Float32 sst[time = 133][y = 2951][x = 3657];
} sst;
} AVHRRSST/SST.nc;
The reason for the change was to remove an ambiguity because
not including the Structure{} lost scoping information.

I should note that the following url
http://cwcgom.aoml.noaa.gov/thredds/dodsC/AVHRRSST/SST.nc.dds?sst.sst,sst.time
properly returns this:
Dataset {
    Structure {
        Float32 sst[time = 133][y = 2951][x = 3657];
        Float64 time[time = 133];
    } sst;
} AVHRRSST/SST.nc;

However, there is a true error for this url (different from above):
http://ferret.pmel.noaa.gov/geoide/dodsC/PSDgriddedData/ncep.reanalysis.dailyavgs/surface/slp_aggregated.dds?slp.slp,slp.lon
It returns this:
Dataset {
    Grid {
     ARRAY:
        Int16 slp[time = 23322][lat = 73][lon = 144];
     MAPS:
        Float32 lon[lon = 144];
    } slp;
} PSDgriddedData%2fncep%2ereanalysis%2edailyavgs%2fsurface%2fslp_aggregated;

This is a error because it is a malformed Grid rather than a Structure.
It only seems to happen when the last map is in the projection set.

I should note that if I do this corresponding request
with the first url:
http://cwcgom.aoml.noaa.gov/thredds/dodsC/AVHRRSST/SST.nc.dds?sst.sst,sst.x
it works ok; no idea why.




=Dennis Heimbigner
  Unidata


Ticket Details
===================
Ticket ID: QTC-832048
Department: Support netCDF
Priority: Normal
Status: Closed