Dear Dirk
I believe that this distinction can be recorded by the existing mechanisms
of "where" and "over" in cell_methods, using the existing standard_name of
sea_ice_thickness. Please see Section 7.3.3 of the CF standard. The grid-box-
mean sea-ice thickness is "area: mean where all_area_types" and the thickness
meaned over sea-ice only is "area: mean where sea_ice", I think.
Best wishes
Jonathan
----- Forwarded message from Dirk Notz <dirk.notz at mpimet.mpg.de> -----
> Date: Tue, 19 Jul 2016 09:53:02 +0200
> From: Dirk Notz <dirk.notz at mpimet.mpg.de>
> To: cf-metadata at cgd.ucar.edu
> Subject: [CF-metadata] CMIP6 Sea Ice MIP: Ice thickness
> User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
> Thunderbird/38.8.0
>
> Dear CF community,
>
> traditionally, the variable sea_ice_thickness from CMIP-type model
> output was calculated by dividing the entire volume of sea ice in a grid
> cell by the entire area of the grid cell, independent of the area
> fraction of the grid cell that was actually covered by sea ice.
>
> This gave rise to substantial confusion for users who expected that
> sea_ice_thickness as stored within CMIP simulations refers to the actual
> sea-ice thickness that is used in the sea-ice model code to calculate
> heat fluxes, for example, rather than the average ice thickness that the
> ice would have if it were to cover the entire area of the grid cell
> while conserving its volume.
>
> To prevent such confusion in the future, we would like to add the
> following variable to the CF convention:
>
> 1. equivalent_sea_ice_thickness (new variable with units 'm3 m-2' or 'm')
> to describe sea-ice volume per grid-cell area
>
> The term "Equivalent sea-ice thickness" is known within the sea-ice
> community to refer to "sea-ice volume per grid-cell area". Ideally, we
> would have liked to suggest a variable name containing the term
> "volume", but this seems difficult within the CF convention as then
> units couldn't be 'm'.
>
> Thank you very much for any feedback, help and guidance.
>
> Best,
>
> Dirk Notz
>
>
>
> --
> ----
> Dr. Dirk Notz
> http://www.mpimet.mpg.de/~notz.dirk
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----- End forwarded message -----
Received on Wed Jul 20 2016 - 07:21:38 BST
