[GRASS-user] datum vs. sphere (grib files)

GRASS GRASS user
1

Hi,

I am currently using some grib files for meteorological data. When I set a location referring to a “georeferenced grib file”, a default WGS84 is assigned to it, because datum is “unknown”

datum: ** unknown (default: WGS84) **

Actually, the grib files are referred to a sphere, so that there is an error related to the use of WGS84. Usually the resolution of grib data is so coarse that it doesn’t really affect the information, but now I need to estimate correctly the error in a given point. To do that, I need to define in GRASS a location using the “sphere” instead of the default WGS84. How can I do that? Is there in PROJ4 the definition of “sphere”, and a related EPSG? why is it unknown?

Thanks for any hint.

Regards,

–
Dr. Margherita Di Leo

2

On Fri, Aug 24, 2012 at 2:19 PM, Margherita Di Leo <diregola@gmail.com> wrote:

Hi,

I am currently using some grib files for meteorological data. When I set a
location referring to a "georeferenced grib file", a default WGS84 is
assigned to it, because datum is "unknown"

datum: ** unknown (default: WGS84) **

Actually, the grib files are referred to a sphere,

...
could you post the gdalinfo output?

Markus