Thanks Bert,
You've persuaded me that the proposed reference surface should be beneath any ice cover.
We still need to decide what to call it!
Cheers, Roy.
Please note that I partially retired on 01/11/2015. I am now only working 7.5 hours a week and can only guarantee e-mail response on Wednesdays, my day in the office. All vocabulary queries should be sent to enquiries at bodc.ac.uk. Please also use this e-mail if your requirement is urgent.
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From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of Bert Jagers <Bert.Jagers at deltares.nl>
Sent: 29 February 2016 23:20
To: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] vertical coordinate for bed stratigraphy / sediment layers
Hi Roy, Jonathan,
I hadn't thought much about ice yet; it can be a very difficult subject.
There are artic shores (e.g. northern Alaska) which are mostly composed of ice and a little bit of sediment. This part of the ice would most definitely be below the to-be-named surface; this is part of the permafrost and generally considered part of the land.
However, in the context of floating ice on oceans I would say that the ice is most definitely above the to-be-named surface. For consistency reasons I would like to refer to grounded ice floats in the nearshore region as above the to-be-named surface also; it would be strange to switch definition once the ice touches the bed. This convention should be consistent for ice on lakes, and snow and glaciers covering the land and streams. Glaciers may extend and retreat during winter and summer; this should NOT represent changes of the to-be-named surface. The to-be-named surface (top of soil, bedrock, or other mineral or biological deposits) would only be changed by geomorphological processes - glacier dynamics might be one of those processes on long time scales.
I believe that the surface of the glacier already coincides with the existing CF surface, i.e. the bottom of the atmosphere (where ice cover on land). So, I'm not sure whether this needs a new name, but if it does I would vote for a different name.
Best regards,
Bert
-----Original Message-----
From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
Sent: 29 February 2016 18:18
To: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] vertical coordinate for bed stratigraphy / sediment layers
Dear Bert and Roy
> In my view this surface could be considered as the top of the ice, not the bottom and then it can be used as the reference for ice core data.
That is true. I suppose that sediments under ice would be more likely to be referred to bedrock (as a surface name) anyway.
> The problem with naming something like this is that so many different communities are involved so any name with a semantic content will attract criticism. Could we possibly circumvent this by using a namespace-based approach such as cf_solid_surface?
I suppose so, but we have not done so in any other standard name. In many of them we use words and phrases with meaning which is precise in CF, although consistent with the vaguer meaning the word/phrase might have elsewhere. I hope we can do the same in this case.
I think soil is an odd word for the bottom of the ocean or for the land surface in regions with no soil. Bert thinks sediments are not solid. We need to think further about this then! The surface to be named is the bottom of the ocean in ocean regions, the bottom of the atmosphere over land. I called this "solid"
because it's not gas or liquid, referring to the classes gas/liquid/solid. Are there any synonyms for "solid" in that sense?
Best wishes
Jonathan
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Received on Tue Mar 01 2016 - 06:25:17 GMT
