[CF-metadata] additional standard name for ISMIP6
taylor13 at llnl.gov
Wed Jan 25 11:20:46 MST 2017
Hi Alison and Jonathan,
I'm confused by the following discussion:
>>>> 17. land_ice_mass_not_displacing_sea_water (kg)
>> The name and units are agreed. I suggest the following as the definition:
>> ' "Land ice not displacing sea water" means land ice that would not alter sea level if removed. It excludes ice shelves and grounded ice-sheets resting on bedrock that is below sea level. It includes glaciers, floating ice caps and ice-sheets resting on bedrock above sea level. The quantity with standard name land_ice_mass_not_displacing_sea_water is the total mass integrated over an area of land ice. The geographical extent of the ice over which the mass was calculated should be described by providing bounds on the horizontal coordinate variables.'
>> Is the bit about glaciers and ice caps correct? I put it in because the definition of land_ice usually refers to them and I want to be as clear as possible about how this name differs from the others.
> Glaciers is correct, but not "floating ice caps". You could say "ice caps".
> Glaciologists use "ice cap" to mean a thing like a glacier or an ice sheet
> but of intermediate size. (Journalists, confusingly, sometimes use "ice cap"
> to refer to Arctic sea-ice.)
In the first sentence does "would not alter sea level if removed" mean
the same thing as "would not alter sea level if melted (assuming the
water runs into the sea)"? If so, I would rewrite the next two sentence
something like "It excludes ice shelves (and any other sort of floating
ice) and it excludes a fraction of grounded ice-sheet mass equivalent to
the mass of any sea water it displaces. It includes glaciers and a
portion the portion of grounded ice-sheet mass exceeding the mass of any
sea water displaced." I think mentioning "ice caps" confuses things.
I think this better accounts for the difference in density of frozen
water and liquid water. Perhaps that density difference isn't large
enough to matter. If so, then I think you could say "It excludes ice
shelves (and any other sort of floating ice) and the portion of grounded
ice-sheets that is below sea level. It includes glaciers and the mass
of grounded ice-sheets existing above sea level."
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