NetCDF file

[Li,Guilong [Ontario]]

Hi Everyone

I am trying to read NCEP North American Regional Reanalysis data in
NetCDF format. I tried to use sdfopen to open the file, but it gave me
the following error message.

SDF file has no discernable X coordinate.

I checked the user group regarding this error message and it says
"netcdf file was not constructed according to COARDS rules". I do not
understand why sdfopen works for NCEP reanalysis data (2.5x2.5), but it
doesn't work for NCEP NARR data. Anyway,I tried to use xdfopen to read
NARR NetCDF data, it still doesn't work. The following is the "ncdump
-c" output. Thanks.

Guilong

netcdf air.197901 {
dimensions:
        y = 277 ;
        x = 349 ;
        level = 29 ;
        time = UNLIMITED ; // (248 currently)
variables:
        float level(level) ;
                level:units = "millibar" ;
                level:actual_range = 1000.f, 100.f ;
                level:long_name = "Level" ;
                level:positive = "down" ;
                level:GRIB_id = 100s ;
                level:GRIB_name = "hPa" ;
                level:axis = "Z" ;
                level:coordinate_defines = "point" ;
        float lat(y, x) ;
                lat:long_name = "latitude coordinate" ;
                lat:units = "degrees_north" ;
                lat:standard_name = "latitude" ;
                lat:axis = "Y" ;
                lat:coordinate_defines = "point" ;
        float lon(y, x) ;
                lon:units = "degrees_east" ;
                lon:long_name = "longitude coordinate" ;
                lon:standard_name = "longitude" ;
                lon:axis = "X" ;
                lon:coordinate_defines = "point" ;
        double time(time) ;
                time:units = "hours since 1800-1-1 00:00:0.0" ;
                time:long_name = "time" ;
                time:actual_range = 1569072., 1569813. ;
                time:delta_t = "0000-00-00 03:00:00" ;
                time:standard_name = "time" ;
                time:axis = "T" ;
                time:coordinate_defines = "point" ;
        float x(x) ;
                x:long_name = "eastward distance from southwest corner
of domain in projection coordinates" ;
                x:units = "m" ;
                x:standard_name = "projection_x_coordinate" ;
        float y(y) ;
                y:long_name = "northward distance from southwest corner
of domain in projection coordinates" ;
                y:units = "m" ;
                y:standard_name = "projection_y_coordinate" ;
        short air(time, level, y, x) ;
                air:long_name = "3-hourly Air Temperature on Pressure
Levels" ;
                air:valid_range = -32765s, -10260s ;
                air:unpacked_valid_range = 137.5f, 362.5f ;
                air:actual_range = 189.3768f, 309.3121f ;
                air:units = "degK" ;
                air:add_offset = 465.15f ;
                air:scale_factor = 0.01f ;
                air:missing_value = 32766s ;
                air:_FillValue = -32767s ;
                air:precision = 2s ;
                air:least_significant_digit = 1s ;
                air:GRIB_id = 11s ;
                air:GRIB_name = "TMP" ;
                air:var_desc = "Air temperature" ;
                air:dataset = "NARR 3-hourly" ;
                air:level_desc = "Pressure Levels" ;
                air:statistic = "Individual Obs" ;
                air:parent_stat = "Other" ;
                air:standard_name = "air_temperature" ;
                air:grid_mapping = "Lambert_Conformal" ;
                air:coordinates = "lat lon" ;
        int Lambert_Conformal ;
                Lambert_Conformal:grid_mapping_name =
"lambert_conformal_conic" ;
                Lambert_Conformal:standard_parallel = 50., 50. ;
                Lambert_Conformal:longitude_of_central_meridian = -107.
;
                Lambert_Conformal:latitude_of_projection_origin = 50. ;
                Lambert_Conformal:false_easting = 5632642.22547 ;
                Lambert_Conformal:false_northing = 4612545.65137 ;

// global attributes:
                :Conventions = "CF-1.0" ;
                :title = "8x Daily NARR" ;
                :history = "created 2005/07 by Hoop (netCDF2.3)" ;
                :comments = "Data is from North American Regional
Reanalysis\n",
    "(8x/day).  It consists of most variables interpolated to\n",
    "pressure surfaces from model (sigma) surfaces." ;
                :institution = "National Centers for Environmental
Prediction" ;
                :platform = "Model" ;
                :references =
"http://wwwt.emc.ncep.noaa.gov/mmb/rreanl/index.html\n",
    "http://www.cdc.noaa.gov/cdc/data.narr.html" ;
}