[CF-metadata] CF and a representation of probalistic forecasts

[Karl Taylor]

Hi Jamie, Jonathan, and all,

Concerning realization weights and pdf's, Jamie wrote:

> This is clearly a special handling of a fifth dimension: how do we
> expect applications that are CF1.0 compliant to support the addition of
> the standard names 'realization' and 'realization_weight'?  Should they
> treat them as special standard names (as latitude, longitude and
> vertical coordinate types are in spatially referencing the data)? In
> this case this dimension is special in that it allows you to calculate
> statistics across the realizations.  (In that sense 'realization_weight'
> is a little bit like a cell measure - though I'm not sure we'd want to
> go this way 'realization' doesn't really have a scale/units).

I find the idea of using the cell_measure attribute to point to the 
'realization_weight' quite natural and attractive.  There is little 
difference in my mind between "area-weighted" means and 
"realization-weighted" or "sample-weighted" means.  Perhaps the only 
drawback is if you wanted to define several different sets of 
"realization" or "sample" weights for a single variable.  I suspect this 
problem would be rare, but I stand ready to be corrected on this point.

Best regards,
Karl