[gdal-dev] Projection issue with a netcdf file

[Kyle Shannon]

I am downloading a netcdf file from a thredds data server.  It contains 4
grib datasets of weather data.  When I run gdalinfo on one of these
subdatasets, the standard parallels in the netCDF metadata (marked by
astrisks) differs from the standard parallels in the reported Coordinate
system:

kyle at kyle-fs-laptop:~/Desktop$ gdalinfo
NETCDF:"NDFD_TEMP.NC":Maximum_temperature

Driver: netCDF/Network Common Data Format
Files: NDFD_TEMP.NC
Size is 6, 7
Coordinate System is:
PROJCS["unnamed",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            TOWGS84[0,0,0,0,0,0,0],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9108"]],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Lambert_Conformal_Conic_2SP"],
    PARAMETER["standard_parallel_1",0],
    PARAMETER["standard_parallel_2",0],
    PARAMETER["latitude_of_origin",25],
    PARAMETER["central_meridian",0],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0]]
Origin = (-1592.424266064417225,2268.326251018509083)
Pixel Size = (5.079361328124969,-5.079472167968713)
Metadata:
  NC_GLOBAL#Conventions=CF-1.0
  NC_GLOBAL#Originating_center=US National Weather Service (NCEP) subcenter
= 5
  NC_GLOBAL#Generating_Process_or_Model=Forecast
  NC_GLOBAL#Product_Status=Operational products
  NC_GLOBAL#Product_Type=Forecast products
  NC_GLOBAL#cdm_data_type=GRID
  NC_GLOBAL#creator_name=US National Weather Service (NCEP) subcenter = 5
  NC_GLOBAL#file_format=GRIB-2
  NC_GLOBAL#History=Translated to CF-1.0 Conventions by Netcdf-Java CDM
(NetcdfCFWriter)
Original Dataset = NDFD-CONUS_5km_best.ncd; Translation Date = Tue Jan 05
10:22:42 MST 2010
  NC_GLOBAL#_CoordinateModelBaseDate=2009-11-21T12:00:00Z
  Maximum_temperature#long_name=Maximum_temperature @ height_above_ground
  Maximum_temperature#units=K
  Maximum_temperature#missing_value=nan

...

time1#_CoordinateAxisType=Time
  Lambert_Conformal#grid_mapping_name=lambert_conformal_conic
  Lambert_Conformal#standard_parallel=25
  Lambert_Conformal#longitude_of_central_meridian=265
  Lambert_Conformal#latitude_of_projection_origin=25
  Lambert_Conformal#earth_shape=Earth spherical with radius specified by
producer
  Lambert_Conformal#spherical_earth_radius_meters=6.3712e+06
  Lambert_Conformal#GRIB_param_Dx=5079.36
  Lambert_Conformal#GRIB_param_Dy=5079.47
  Lambert_Conformal#GRIB_param_GDSkey=801839731
  Lambert_Conformal#GRIB_param_La1=20.192
  Lambert_Conformal#GRIB_param_LaD=25
**
  Lambert_Conformal#GRIB_param_Latin1=25
  Lambert_Conformal#GRIB_param_Latin2=25
**
  Lambert_Conformal#GRIB_param_Lo1=238.446
  Lambert_Conformal#GRIB_param_LoV=265
  Lambert_Conformal#GRIB_param_NpProj=true
  Lambert_Conformal#GRIB_param_Nx=1073
  Lambert_Conformal#GRIB_param_Ny=689
  Lambert_Conformal#GRIB_param_ProjFlag=0
  Lambert_Conformal#GRIB_param_Quasi=false
  Lambert_Conformal#GRIB_param_ResCompFlag=8
  Lambert_Conformal#GRIB_param_SpLat=-90
  Lambert_Conformal#GRIB_param_SpLon=0
  Lambert_Conformal#GRIB_param_VectorComponentFlag=gridRelative
  Lambert_Conformal#GRIB_param_Winds=Relative
  Lambert_Conformal#GRIB_param_grid_name=Lambert_Conformal
  Lambert_Conformal#GRIB_param_grid_radius_spherical_earth=6.3712e+06
  Lambert_Conformal#GRIB_param_grid_shape=Earth spherical with radius
specified by producer
  Lambert_Conformal#GRIB_param_grid_shape_code=1
  Lambert_Conformal#GRIB_param_grid_type=30
  Lambert_Conformal#GRIB_param_grid_units=m
  Lambert_Conformal#_CoordinateTransformType=Projection
  Lambert_Conformal#_CoordinateAxisTypes=GeoX GeoY
Corner Coordinates:
Upper Left  (   -1592.424,    2268.326)
Lower Left  (   -1592.424,    2232.770)
Upper Right (   -1561.948,    2268.326)
Lower Right (   -1561.948,    2232.770)
Center      (   -1577.186,    2250.548)
Band 1 Block=6x1 Type=Float32, ColorInterp=Undefined

...

I am curious where this discrepancy is taking place.  I kind of think it is
a typo or a mistake from the data server, but I can't peg it down.  Any
thoughts?  Thanks.

kss

# ===================
Kyle Shannon
Physical Science Technician
RMRS Fire Sciences Lab
Fire, Fuels & Smoke - RWU 4405
5775 Highway 10 W.
Missoula, MT 59808
(406)646-6577
kshannon at fs.fed.us
ksshannon at gmail.com
# ===================
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