[CF-metadata] moving horizontal coordinate system

[John Caron]

Ive run into an interesting use case, we have a series of model runs that are tracking some moving weather. The projection is changing its parameters from one run to the next, eg:

model run n:

   char Lambert_Conformal;
     :grid_mapping_name = "lambert_conformal_conic";
     :standard_parallel = 30.079; 
     :longitude_of_central_meridian = -86.117; 
     :latitude_of_projection_origin = 30.079; 

model run n+1:

   char Lambert_Conformal;
     :grid_mapping_name = "lambert_conformal_conic";
     :standard_parallel = 29.474; 
     :longitude_of_central_meridian = -85.158; 
     :latitude_of_projection_origin = 29.474; 


I was going to try to create an aggregated dataset out of these runs, and allow users to slice it in various ways. But I dont think we have a way of encoding this, since the info is in the attributes, not in tha data variable values. Anyone have any thoughts (other than reprojecting, which i dont plan to do)?