Re: [netcdfgroup] Using IDL to generate NetCDF 4 files

• To: 'Ajay Krishnan - NOAA Affiliate' <ajay.krishnan@xxxxxxxx>, "netcdfgroup@xxxxxxxxxxxxxxxx" <netcdfgroup@xxxxxxxxxxxxxxxx>
• Subject: Re: [netcdfgroup] Using IDL to generate NetCDF 4 files
• From: Mark Rivers <rivers@xxxxxxxxxxxxxxxxx>
• Date: Wed, 13 May 2015 20:23:31 +0000

I have only used IDL to create netCDF3 files, not netCDF4 files.  However, I 
suspect that the code needs to be changed similar to the following:

From

      ncdf_attput, lat_id, 'standard_name’, ‘latitude’

to

      ncdf_attput, lat_id, 'standard_name’, ‘latitude’, /char

The /char means to store the data as a byte array, rather than a string.  It is 
possible that the existing code is explicitly using the /string keyword, which 
would need to be replaced with /char.

Mark


From: netcdfgroup-bounces@xxxxxxxxxxxxxxxx 
[mailto:netcdfgroup-bounces@xxxxxxxxxxxxxxxx] On Behalf Of Ajay Krishnan - NOAA 
Affiliate
Sent: Wednesday, May 13, 2015 3:02 PM
To: netcdfgroup@xxxxxxxxxxxxxxxx
Subject: [netcdfgroup] Using IDL to generate NetCDF 4 files

Hi everyone,

One of the data producers that I am working with is using IDL to generate 
NetCDF-4 files.

I am not sure about the code that he is using to generate these files but I am 
unable to read them in THREDDS.

An ncdump of the file looks like this:

netcdf baa_b05kmnn_20150101 {
dimensions:
        time = 1 ;
        lat = 3600 ;
        lon = 7200 ;
variables:
        int time(time) ;
                string time:long_name = "reference time of sst field" ;
                string time:standard_name = "time" ;
                string time:axis = "T" ;
                string time:calendar = "Gregorian" ;
                string time:units = "seconds since 1981-01-01 00:00:00" ;
                string time:comment = "Nominal time of Level 4 analysis" ;
                string time:coverage_content_type = "coordinate" ;
        float lat(lat) ;
                string lat:long_name = "latitude" ;
                string lat:standard_name = "latitude" ;
                string lat:units = "degrees_north" ;
                string lat:axis = "Y" ;
                lat:valid_min = -90.f ;
                lat:valid_max = 90.f ;
                string lat:comment = "equirectangular projection" ;
                string lat:coverage_content_type = "coordinate" ;
                string lat:grid_mapping = "crs" ;
        float lon(lon) ;
                string lon:long_name = "longitude" ;
                string lon:standard_name = "longitude" ;
                string lon:units = "degrees_east" ;
                string lon:axis = "X" ;
                lon:valid_min = -180.f ;
                lon:valid_max = 180.f ;
                string lon:comment = "equirectangular projection" ;
                string lon:coverage_content_type = "coordinate" ;
                string lon:grid_mapping = "crs" ;
        byte surface_flag(lat, lon) ;
                string surface_flag:long_name = "Pixel characteristics flag 
array" ;
                string surface_flag:units = "none" ;
                string surface_flag:coordinates = "lon lat" ;
                string surface_flag:comment = "An array in the same dimension 
as the data array classifies land, missing, and ice pixels that are all flaged 
by the same missing_value in the data array(s)." ;
                surface_flag:flag_values = 0s, 1s, 2s, 4s ;
                string surface_flag:flag_meanings = 
"valid-water,land,missing,ice" ;
                string surface_flag:coverage_content_type = 
"thematicClassification" ;
                string surface_flag:grid_mapping = "crs" ;


I guess the issue is arriving from the prefix 'string' which probably crept in 
while generating the attributes. When I get rid of the 'string' and recreate 
the NetCDF file, it works absolutely fine.

Since I don't have an idea as to how IDL works, can someone here guide me as to 
how this can be avoided while generating the netcdf file from IDL?

This issue arises only when the data provided creates NetCDF 4 files. The 
NetCDF 3 files run just fine.

Any help / documentation would be appreciated.

Thanks,
Ajay

• Follow-Ups:
  • Re: [netcdfgroup] Using IDL to generate NetCDF 4 files
    • From: Ajay Krishnan - NOAA Affiliate

• References:
  • [netcdfgroup] Using IDL to generate NetCDF 4 files
    • From: Ajay Krishnan - NOAA Affiliate