Dear All,
in addition to 24 standard names for SIMIP which are in the standard name editor (Current status of proposals for new standard names<
http://cfeditor.ceda.ac.uk/proposals/1?status=active&namefilter=&proposerfilter=&descfilter=&filter+and+display=filter>), there are 5 names and one area type needed:
(1) siflfwdrain Freshwater flux from sea-ice surface [kg m-2 s-1]
I think this variable was added later than the others. We already have, in the CF editor: water_flux_into_sea_water_from_sea_ice
The variable name refers to the process of drainage, so I suggest we use the standard name construction referring to a specific process:
water_flux_into_sea_water_from_sea_ice_due_to_surface_drainage
(2) snmassacrossline Snow mass flux through straits (kg s-1)
For sea ice we have sea_ice_transport_across_line. We might try snow_transport_across_line, but that would probably be interpreted as including transport of snow in the atmosphere, hence:
snow_transport_across_line_due_to_sea_ice_dynamics
(3) Stresses and strains
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There are 3 stress/strain variables (see below) for which I think we need a bit more information. Presumably these refer to the horizontal stress and strain fields? Since these are rank two tensors, the first invariant will be the trace, or sum of eigenvalues, and the 2nd will be the determinant, or product of eigenvalues. Given the units, it looks as though you are interpreting the 2nd invariant as the square root of the determinant? I found one source which suggest that the square root of the 2nd invariant is often used instead of the invariant itself, and referred to as the "effective stress" (e.g.
http://www.engr.colostate.edu/~thompson/hPage/CourseMat/Tutorials/Solid_Mechanics/J2.pdf -- effective stress = square root [ 3 * 2nd invariant] ), but I don't know how wide spread this usage is.
We don't have any standard names referring to the invariants of tensors, so we need some new terminology here. I propose using "horizontal_strain/stress_tensor" to refer to two tensors, and "trace" and "second_invariant" to refer to the properties of interest. In addition, since the term "second invariant" can refer to either a quantity which is a quadratic function of matrix components or its square root, I propose adding "expressed_as_effective_strain" to indicate that we are using the 2nd option here.
(3a) sishevel Maximum shear of sea-ice velocity field (s-1)
Maximum shear of sea-ice velocity field (second shear strain invariant)
sea_ice_second_invariant_of_horizontal_strain_tensor_expressed_as_effective_strain
The last part, "_expressed_as_effective_stress" may be needed to deal with the fact that the second invariant would usually have units s-2.
(3b) sistremax Maximum shear stress in sea ice (N m-1)
Maximum shear stress in sea ice (second stress invariant)
sea_ice_second_invariant_of_horizontal_stress_tensor_expressed_as_effective_stress
(3c) sistresave Average normal stress in sea ice (N m-1)
Average normal stress in sea ice (first stress invariant)
sea_ice_trace_of_horizontal_stress_tensor
Here we can just refer to the trace, but the help text could also refer to the "first invariant".
(4) Percentage Cover of Sea-Ice by Ridging
We need a new area_type (as discussed in
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2016/058902.html ):
ridged_sea_ice
regards,
Martin
Received on Wed Apr 25 2018 - 04:00:17 BST
