[CF-metadata] CF and multi-forecast system ensemble data

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 18 Oct 2006 16:12:02 +0100

Dear Paco

Thank you for this detailed description.

I think realization is identical in purpose with ensemble_member_number, isn't
it. From this description it seems like you also want to describe the model or
its version, don't you? This will be some string, presumably. If it is the
*combination* of model identity and ensemble member which characterises the
data, perhaps this is another case for an "index" axis with these two parts of
the description as two auxiliary coordinate variables of that axis.

Maybe people who have thought about discovery metadata (not me) might have
views on this.

Best wishes

Jonathan

> For instance, imagine a multi-model forecast (for the medium-range,
> monthly, seasonal or interannual time scales) built up from forecasts
> issued by several GCMs or by a number of versions of a single GCM. Each
> GCM or model version is supposed to have the possibility of issuing an
> ensemble of forecasts by perturbing the initial conditions. The members
> of such an multi-forecast system ensemble forecast can not all be dealt
> with in a similar way. For a given GCM or single-model version, the
> ensemble members might have similar statistical properties (e.g., in an
> initial-condition perturbation ensemble setting), but those ensemble
> members will likely have different statistical properties when compared
> to those from another GCM or single-model version, which are also part
> of the same multi-forecast system ensemble forecast. In my opinion, it
> is impossible to identify to which forecast system each member belongs
> to when only using the realization variable.
>
> The example above is only one among a set of multi-forecast system
> predictions currently generated operationally (eg, the EUROSIP
> multi-model seasonal forecasts) or under development (TIGGE medium-range
> forecasts or the ENSEMBLES seasonal-to-decadal predictions). The
> closeness to the operational activity prevents some of these communities
> from using NetCDF because of the lack of adequate standards (and use
> GRIB1 or GRIB2 instead). We believe that the variables
> experiment_identifier (along with its auxiliary variables) and
> ensemble_member_number can handle this problem.
>
> Best regards,
> Paco
Received on Wed Oct 18 2006 - 09:12:02 BST