Date: Fri Dec 02 2011 - 02:36:33 MST
Dear people,
I have a problem with plotting cut files of ERA-Interim data in grib format in NCL. Plotting, using the global file works perfectly. Now I want to make the same plot, but from cut files for a specific region (lon:-60 to 100, lat: -10 to 90). The ERA-Interim data is cut with use of the CDO package of Max Planck Institute, using the command: 'cdo sellonlatbox'. However, when I plot the data, NCL gives the warning below. See also attached text file with warning and the 'printVarSummaries' for original(global) and experiment (cut files) variables.
warning:GdsGAGrid: GRIB attributes La1 and/or La2 are incorrectly out of range of the gaussian latitude array (See GRIB Section 2 documentation)
warning:GdsGAGrid: Gaussian latitude coordinate array is partially or wholly undefined
The plot is flipped and stretched over the latitudes (see plot attached). Inverting the latitudes does not help, the plot is still stretched. Apparently NCL has difficulties dealing with latitude coordinates. I do not know if the problem happens in NCL, or that the problem originates from cutting the files, leading to loss of coordinates or metadata. Using wgrib command, the cut grib file seems okay. I also did some experiments with cutting data for specific index instead of lat-lon coordinates as well as switching coordinates in the cdo command, but it all did not make any difference.
I did another experiment, cutting the data for lon:-60 to 100, but with the full latitudes: -90 to 90. In this case, NCL handles the cut file perfectly without any problem, see the second attached plot.
Does anyone have any idea about this problem? Suggestions would be most welcome. Thanks a lot!
Cheers,
Andries
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