How to open GRIB2 file using ncgeodatset?

Hi everyone,

I am trying to open a 'GRIB2' file using ncgeodataset. But I am not able to do it.

fname = 'E:\NCEP\fnl_20170603_06_00.grib2'
ds = ncgeodataset(fname);

After I run above two lines, these are the results. Can somebody tell me what is the issue here. Thank you

fname =

    'E:\NCEP\fnl_20170603_06_00.grib2'

2022-05-26 19:40:45,657 [main] WARN  ucar.nc2.grib.grib2.Grib2CollectionBuilder  - GribCollection fnl_20170603_06_00.grib2: invalid index 

2022-05-26 19:40:45,657 [main] WARN  ucar.nc2.grib.GribCollection  - Failed to delete E:\NCEP\fnl_20170603_06_00.grib2.ncx

Warning: Escaped character '\N' is not valid. See 'doc sprintf' for supported special characters. 
> In ncdataset (line 95)
In cfdataset (line 59)
In ncgeodataset (line 74) 
Error using ncdataset (line 97)
Failed to open E:

Error in cfdataset (line 59)
            obj = obj@ncdataset(url);

Error in ncgeodataset (line 74)
            obj = obj@cfdataset(url);

Caused by:
    Error using ncdataset (line 81)
    Java exception occurred:
    java.lang.UnsupportedOperationException: This is supposed to be overridden by subclasses.

    	at com.google.protobuf.GeneratedMessage.getUnknownFields(GeneratedMessage.java:262)

    	at ucar.nc2.grib.GribCollectionProto$Record.getSerializedSize(GribCollectionProto.java:162)

    	at com.google.protobuf.CodedOutputStream.computeMessageSizeNoTag(CodedOutputStream.java:916)

    	at com.google.protobuf.CodedOutputStream.computeMessageSize(CodedOutputStream.java:668)

    	at ucar.nc2.grib.GribCollectionProto$VariableRecords.getSerializedSize(GribCollectionProto.java:657)

    	at com.google.protobuf.AbstractMessageLite.toByteArray(AbstractMessageLite.java:70)

    	at ucar.nc2.grib.grib2.Grib2CollectionBuilder.createIndex(Grib2CollectionBuilder.java:558)

    	at ucar.nc2.grib.grib2.Grib2CollectionBuilder.createIndex(Grib2CollectionBuilder.java:415)

    	at ucar.nc2.grib.grib2.Grib2CollectionBuilder.readOrCreateIndex(Grib2CollectionBuilder.java:157)

    	at
        ucar.nc2.grib.grib2.Grib2CollectionBuilder.readOrCreateIndexFromSingleFile(Grib2CollectionBuilder.java:77)

    	at ucar.nc2.grib.GribIndex.makeGribCollectionFromSingleFile(GribIndex.java:123)

    	at ucar.nc2.grib.grib2.Grib2Iosp.open(Grib2Iosp.java:310)

    	at ucar.nc2.NetcdfFile.<init>(NetcdfFile.java:1499)

    	at ucar.nc2.NetcdfFile.open(NetcdfFile.java:887)

    	at ucar.nc2.NetcdfFile.open(NetcdfFile.java:496)

    	at ucar.nc2.dataset.NetcdfDataset.openOrAcquireFile(NetcdfDataset.java:693)

    	at ucar.nc2.dataset.NetcdfDataset.openDataset(NetcdfDataset.java:424)

    	at ucar.nc2.dataset.NetcdfDataset.openDataset(NetcdfDataset.java:407)

    	at ucar.nc2.dataset.NetcdfDataset.openDataset(NetcdfDataset.java:392)

    	at ucar.nc2.dataset.NetcdfDataset.openDataset(NetcdfDataset.java:379)

[jessupj]

I think this is an external tool (https://github.com/nctoolbox). You're better off asking around the developer instead of this community, as it's probbaly not a matlab-itself problem.

(My guess is opendap problems or an incompatible JVM version. if your gribfile is local, have you tried converting it to netcdf in ncl and loading it with the matlab function ncread? That way, it's at least in 'matlab' rather than a 3rd party tool and you're likely to get more help here.)

Answer 1

[Jacob Halbrooks]

As of R2023b, you can read data from a GRIB file (.grb, .grib, .grib2) using the Mapping Toolbox readgeoraster function. You can also get information about a GRIB file by using the georasterinfo function. These functions were enhanced in R2024b to support GRIB files that use CCSDS compression.