[ncl-talk] Problems with reading and re-gridding polar stereographic grid data

[Tsai Judy]

Hi,

I think the problem I have is that my Greenland bed elevation data doesn't
have any lat lon information just like the data set you suggest (
land5.input.nc ).


-----
    float lat(time, y1, x1) ;
        lat:grid_mapping = "mapping" ;
        lat:long_name = "Latitude" ;
        lat:standard_name = "latitude" ;
        lat:units = "degreeN" ;
    float lon(time, y1, x1) ;
        lon:grid_mapping = "mapping" ;
        lon:long_name = "Longitude" ;
        lon:standard_name = "longitude" ;
        lon:units = "degreeE" ;
-----

And my data set only has "projection_x_coordinate(x)" and
"projection_y_coordinate(y)" information
----
    float projection_x_coordinate(x) ;
        projection_x_coordinate:units = "kilometres" ;
        projection_x_coordinate:standard_name = "projection_x_coordinate" ;
        projection_x_coordinate:long_name = "x coordinate of projection" ;
    float projection_y_coordinate(y) ;
        projection_y_coordinate:units = "kilometres" ;
        projection_y_coordinate:standard_name = "projection_y_coordinate" ;
        projection_y_coordinate:long_name = "y coordinate of projection" ;
    float BedrockElevation(y, x) ;
        BedrockElevation:units = "metres" ;
        BedrockElevation:grid_mapping = "Polar-Stereographic" ;
        BedrockElevation:coordinates = "projection_x_coordinate
projection_y_coordinate" ;
        BedrockElevation:missing_value = " -9999." ;
        BedrockElevation:standard_name = "BedrockElevation" ;
        BedrockElevation:long_name = "Bedrock elevation with respect to the
EIGEN-GL04C geoid for Greenland. Please discuss correct acknowledgement and
referencing with J. Bamber before publishing any results using these data."
;
----

So my question is that is there anyway I can obtain real lat/lon
information from "projection_x_coordinate(x)" and
"projection_y_coordinate(y)" with NCL in order to regird that into T31 grid?

Thank you



2015-04-06 19:22 GMT-04:00 Dennis Shea <shea at ucar.edu>:

> Not sure if the following are related to:
>       "... Greenland bed elevation data set ..."
>
> See: http://www.ncl.ucar.edu/Applications/ESMF.shtml
>         Example 33
>
> See: http://www.ncl.ucar.edu/Applications/ice.shtml
>         gland section
>
> The land5.input.nc file is at
>
> www.cgd.ucar.edu/~shea/gland5.input.nc
>
> HTH
>
> On Mon, Apr 6, 2015 at 3:11 PM, Tsai Judy <judytsaibuy at gmail.com> wrote:
>
>> Hi,
>>
>> I have a Greenland bed elevation data set (.nc file) with polar
>> stereographic grid and I want to re-grid that into CCSM T31 grid in order
>> to calculate the difference between them. However, my Greenland bed
>> elevation data set doesn't have the associated longitude and latitude
>> information (i.e lon2d and lat2d) within the nc file. It just has "
>> projection_x_coordinate (x)" and " projection_y_coordinate (y)." Can anyone
>> suggest that is there any way (or function) available in NCL that I can use
>> to deal with this issue?
>>
>> Thanks
>>
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>
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