[CF-metadata] Re: projections in CF

[John Caron]

With respect to the current CF proposal on projections, Russ and I agree that

1) it would be better to specify the individual projection parameters as individual attributes, 
rather than parsing strings. eg instead of

float T(lev, y, x) ;
  T:grid_mapping = "lambert_conformal_conic standard_parallel: 25.0 \n";
   "longitude_of_central_meridian: -95.0 latitude_of_projection_origin: 25.0";

use:

float T(lev, y, x) ;
   T:projectionName = "Lambert_Conformal_Conic";
   T:Standard_Parallel="25.0";
   T:Longitude_of_Central_Meridian="-95.0";
   T:Latitude_of_Projection_Origin="25.0";
   

2) the common case is to replicate the projection specification on all variables; 
it would be useful to be able to factor the projection out so it is specified
in only one place. 

it seems that software to subset a file already has to know to keep the coordinate variables and
other auxiliary information, so having to know to include projection info seems not much different.


3) while we think these would be improvements, the current proposal is also reasonable and we
are anxious for a CF Convention that includes projections soon.