[CF-metadata] Request for standard names: sea ice age and fraction of first year ice

From: Jonathan Gregory <j.m.gregory>
Date: Mon, 30 May 2011 17:07:36 -0000

Dear Thomas

> 1) if an appropriate standard name could be sea_ice_type_classification.
> 2) Do you have previous experience with 'classifications' in CF?

I would say it is not really necessary to introduce a new standard name
for this, because we could use the existing general standard name area_type,
and define some new possible values for it. Indeed, this could be done as an
alternative to defining a specific name for the concentration of first-year
sea-ice. However the drawback is it's more complicated for the user of the
data, who will have to examine the value of a string-valued scalar coordinate
variable giving the area type, not just the standard name attribute.

> 3) if my 'classification' could re-use (in a more generic way) the structure of CF 'flags', with "flag_values", "flag_masks" and "flag_meanings". Since my data would be a 'sea ice type classification' (and not 'flags'), I would fancy using 'sea_ice_type_values', and 'sea_ice_type_meanings' (I would not use 'sea_ice_type_masks').

Again, the existing general mechanism can be used. If a data variable has a
standard name of area_type, it is logical to encode the possible values using
the flag_values and flag_meanings attributes.

> The main point here, is probably to agree if the variable holds a "first year ice fraction of total ice concentration", or a "concentration of first year ice" ("first year ice fraction of total cell area"):

You are right, I created an ambiguity. My suggestion was analogous to existing
names, in which X_area_fraction means the area fraction of the whole grid cell
occupied by type X, and I meant X=first_year_sea_ice. To avoid the ambiguity
we could use a different pattern: area_fraction_of_first_year_sea_ice. But
perhaps it is better anyway to use the area_type method.

Best wishes

Jonathan
Received on Mon May 30 2011 - 11:07:36 BST