Sort out formal experiment description

[bnlawrence]

We are doing "history" and "ssp370", but not quite, because our identifiers will not be from the same stable as the parent (i.e. our variant_label is from a different vocabulary).

We could use those as is, but change the mip-era or parent_id?

We also have to decide whether we want to have two sets of experiments with different attributes, e.g. historical to 2015 and ssp370 thereafter.

Whatever we do, we probably need a formal es-doc definition which describes our initialisation and duration. It might be easier then to use neither historical nor ssp370, and simply call it canari, which can then have it's own document.

[bnlawrence]

What did hiresmip do for the difference in the durations and the names? RS is going to sleep on this one.