Thanks, Sophie, for your quick response. Given your clarification,
perhaps we might replace the description of ice_sheet, which currently
reads:
> ice_sheet: An area type of "ice sheet" indicates where ice sheets are
> present. It includes both grounded ice sheets resting over bedrock and
> ice shelves flowing over the ocean, but excludes ice-caps and glaciers
> (in contrast to land_ice, which includes all components).
with this description:
ice_sheet: An area type of "ice_sheet" indicates where the Greenland and
Antarctic ice sheets are present. It includes both the grounded portion
of those ice sheets (i.e., the portion resting on bedrock either above
or below sea level) and the portion that is floating as ice shelves. It
excludes all other ice on land (in contrast to land_ice, which includes,
for example, small mountain glaciers and in contrast to ice_on_land,
which is comprehensively inclusive of all types of ice on land).
Also I think it should be clarified whether "snow" is considered to be
"ice_on_land". If not, I think the descriptive phrase "any other ice on
a land surface" should be modified to read "any other ice on a land
surface (except snow)".
Best regards,
Karl
On 10/9/18 11:03 AM, Nowicki, Sophie (GSFC-6150) wrote:
Hi Karl,
I am responding to your question about ice_sheet/land_ice (CF-metadata Digest,
Message 2, Vol 186, Issue11), and deleted the other topics from the thread.
ice_sheet would be the Greenland and Antarctic ice sheets. It contains both
the grounded_ice_sheet (part of the ice sheet flowing over bedrock, and you are
technically right that an ice sheet is a combination of many many glaciers) and
floating_ice_shelf (the part that only flows on water).
land_ice is much bigger as it includes the polar ice sheets, glaciers in
non-polar regions (glaciers are considered small body of ice: for example in
the Alps, or the US), and the small ice caps. The ice caps are also a large
combinations of glaciers, but too small to be considered an ice sheets. For
example the Svartissen Ice Cap in northern Norway.
For ISMIP6, we are interested in ice_sheet, but some climate models may also
include glaciers and ice caps (which ISMIP6 does not care about). Hence the use
of both ice_sheet and land_ice in the ISMIP6 protocol (and I cant recall if
land_ice was already present in CMIP5, but I think that it was).
I don’t know the origin of ice_on_land.
Jonathan: please help me make my answers less confusing...
I hope that this helps,
Sophie
Message: 2
Date: Tue, 9 Oct 2018 17:19:36 +0000
From: "Taylor, Karl E." <[email protected]>
To: "[email protected]" <[email protected]>
Subject: Re: [CF-metadata] ice_sheet / land_ice confusion
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
HI all,
Can anyone provide any guidance on the difference between ice_sheet and
land_ice (see below)?? It has a bearing on metadata to be stored with
CMIP6 model output.
thanks and best regards,
Karl
On 10/4/18 10:29 AM, Taylor, Karl E. wrote:
> Hi all,
>
> I think there might be a mistake in the descriptions of "ice_sheet"
> and/or "land_ice" in the "area type" table at
>
http://cfconventions.org/Data/area-type-table/current/build/area-type-table.html
> .
>
> I find there the following definitions:
>
> ice_sheet: An area type of "ice sheet" indicates where ice sheets are
> present. It includes both grounded ice sheets resting over bedrock and
> ice shelves flowing over the ocean, but excludes ice-caps and glaciers
> (in contrast to land_ice, which includes all components).
>
> land_ice: "Land ice" means glaciers, ice-caps, grounded ice sheets
> resting on bedrock and floating ice-shelves.
>
> ice_on_land: The area type "ice_on_land" means ice in glaciers, ice
> caps, grounded ice sheets (grounded and floating shelves), river and
> lake ice, and any other ice on a land surface, such as frozen flood
> water. This is distinct from the area type 'land ice' which has a
> narrower definition.
>
> Are "ice-caps" and "glaciers" really excluded from "ice_sheet".? I would
> have thought that "ice-cap" would be an ice_sheet located over a pole
> (or something to that effect).? And i thought ice_sheets were just big
> glaciers.
>
> ice_on_land is pretty clearly any frozen water, except sea ice,
> icebergs, and ice particles in clouds, that is exposed to the atmosphere.
>
> So, I guess I'm trying to understand the difference between ice_sheet
> and land_ice, and why do we need both of these?
>
> thanks and best regards,
> Karl
End of CF-metadata Digest, Vol 186, Issue 11
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