[CF-metadata] Three questions

[Burkhardt.Rockel at gkss.de]

Hi,

I am implementing netCDF as I/O option in a regional forecast and climate 
model of the atmosphere and try to follow the CF-conventions. Three 
questions arises:
1. The co-ordinate system is rotated lat/lon. I found no information in 
the CF-conventions how to handle this. Would  the "north_pole" attribute 
as described in the GDT-conventions a possibility?
2. The model uses an Arakawa-C grid. Therefore U and V velocities are 
shifted half a grid box. I also found no information in the CF-conventions 
how to handle this. There may be at least two possibilities:
a. defining an attribute "grid_shift" that would be grid_shift=0.5,0. for 
U and grid_shift=0.,0.5 for V 
b. defining two additional co-ordinate fields that contain the shifted 
values
What do you think?
3. The attribute "cell_method" applied to time is like the "time range 
indicator" in the GRIB format definitions (if I understand it right). The 
cell_method can be minimum, maximum, mean and so forth. What is the reason 
that accumulated values are not considered? Wouldn't it be more consistent 
to allow also "sum" or "accumulated" as a cell_method?

Best Regards
Burkhardt


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Dr. Burkhardt Rockel
GKSS Forschungszentrum
Max-Planck-Strasse
D-21502 Geesthacht
Germany
Phone: +49 4152 87 2008
Fax: +49 4152 87 2020
Email: rockel at gkss.de
www: http://w3.gkss.de/KSR/ksr_home.html
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