Dear Martin
I agree that the quantity doesn't exist everywhere, but that's the same if you
give it a name of its own rather than the more general name of depth. I suggest
that specifying the coordinate as soil_temperature specifically implies that
it must be non-existent where 0degC is above ground or there is no ground. The
value to be given in that case needs a convention, though not necessarily as
part of the standard name definition; it could be a CMIP6 convention. It's like
the non-existent thickness of sea ice in ice-free sea or land areas.
Best wishes
Jonathan
----- Forwarded message from Martin Juckes - UKRI STFC <martin.juckes at stfc.ac.uk> -----
> Date: Thu, 17 May 2018 17:26:58 +0000
> From: Martin Juckes - UKRI STFC <martin.juckes at stfc.ac.uk>
> To: Jonathan Gregory <j.m.gregory at reading.ac.uk>, "cf-metadata at cgd.ucar.edu"
> <cf-metadata at cgd.ucar.edu>
> Subject: Re: [CF-metadata] Standard names for LS3MIP: 8 temporal changes + 1
> feature depth
>
> Dear Jonathan,
>
>
> Yes, it should be 0C, not 0K.
>
>
> I don't think the approach you suggest will work because what we need is the depth of the first 0C isotherm assuming surface temperature above 0C. We don't want the depth of the 0C isotherm in regions where the surface temperature is < 0C. I can't see any way to include these conditions in existing CF attributes, can you?
>
>
> regards,
>
> Martin
>
>
>
> ________________________________
> From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of Jonathan Gregory <j.m.gregory at reading.ac.uk>
> Sent: 17 May 2018 17:30
> To: cf-metadata at cgd.ucar.edu
> Subject: [CF-metadata] Standard names for LS3MIP: 8 temporal changes + 1 feature depth
>
> Dear Martin
>
> All the change_over_time ones look fine to me, thanks.
>
> > 2.1 dmlt Depth to soil thaw [m] (CliC)
> > Depth from surface to the zero degree isotherm. Above this isotherm T > 0o, and below this line T < 0o.
> >
> > When the surface temperature is above 0K and there is frozen soil at some point beneath the surface, thawed_soil_depth is the distance from the surface to the first 0K isotherm. When there is no thawed soil layer, the parameter should be reported as missing.
> >
> > + Proposed: thawed_soil_depth
>
> Could we use the standard_name of depth for this, with a coordinate
> variable of soil_temperature=0degC?
> (I think 0degC is intended above, not absolute zero)
>
> Best wishes
>
> Jonathan
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----- End forwarded message -----
Received on Fri May 18 2018 - 01:47:04 BST
