Best regards,
Tuomas Karna
Post-Doctoral Fellow
Center for Coastal Margin Observation and Prediction (CMOP)
Oregon Health and Science University
[email protected]
On 02/27/2013 05:50 AM, [email protected] wrote:
Dear Tuomas,
Thanks for your questions.
Firstly, I should mention that you appear to be looking at a rather old
version of the standard name table (version 16). The table is updated
periodically and the most recently published version can always be
obtained at
http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-name-
table/current/cf-standard-name-table.html.
However, it may be that the current version of the table still does not
contain all the quantities you need, in which case new names can be
proposed on this mailing list.
You say that you are happy to use the existing names
ocean_vertical_momentum_diffusivity (m2 s-1) and
ocean_vertical_tracer_diffusivity (m2 s-1) for the first two quantities in your
list. I think new names may well be needed for the other quantities. When
proposing new names it is always helpful to try to follow as closely as
possible the syntax of existing names. This also helps when writing the
definitions of the names.
1. vertical eddy kinetic energy (per unit mass), unit m2 s-2.
We already have a name specific_kinetic_energy_of_sea_water (m2 s-2)
for which the definition simply says ' "specific" means per unit mass.' We
also have existing names that refer to ocean_eddy_kinetic_energy. Based
on these, I would suggest adding a new name of
specific_vertical_eddy_kinetic_energy_of_sea_water (m2 s-2). Also, based
on the definitions of the existing vertical_X_diffusivity names (where X is
"momentum" or "tracer") I would suggest a definition along the lines of '
"specific" means per unit mass. The construction
"vertical_eddy_kinetic_energy" means the kinetic energy of vertical
motions which are not resolved on the grid scale of the model.'
2. kinetic energy dissipation rate, unit m2 s-3.
There is an existing name
ocean_kinetic_energy_dissipation_per_unit_area_due_to_vertical_friction
with units of W m-2 and a corresponding name
ocean_kinetic_energy_dissipation_per_unit_area_due_to_xy_friction. Your
quantity is not "per_unit_area" so at first sight we might give it a unit of W =
kg m2 s-3. However, you need m2 s-3 which is the same as W kg-1 and this
suggests that we need to add "specific" to the name again. If you want
energy dissipation arising from all possible processes then we wouldn't
need the "due_to_process" phrase so the name would be
ocean_specific_kinetic_energy_dissipation (m2 s-3). However, if you want
to refer specifically to the vertical component of dissipation perhaps you
might want to keep the "due_to_vertical_friction" part?
3. mixing length, unit m.
We don't currently have any standard names related to this quantity. I
think the name needs to be more specific because, for example, we could
have different mixing lengths in atmosphere and ocean. If the mixing length
varies on a large scale then we would probably call it ocean_mixing_length,
but if there is a lot of variation on a small scale then the appropriate name
would be mixing_length_of_sea_water. Also, is the mixing length the same
horizontally and vertically or is there a need to distinguish between
lateral/vertical mixing? Is the mixing length the same for all properties such
as temperature and salinity or do we need to make any distinction? If you
could explain a bit more about the context in which the name will be used it
will be easier to decide on the precise wording and also to produce a
definition.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Email:[email protected]
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
From: CF-metadata [mailto:[email protected]] On
Behalf Of Tuomas Karna
Sent: 27 February 2013 00:26
To:[email protected]
Subject: [CF-metadata] standard names for ocean model turbulent
quantities
Hi All,
We are currently in the process of migrating SELFE outputs to CF
compliant netcdf, using the UGRID conventions (http://bit.ly/ugrid_cf).
I have a question about the standard names for turbulence closures used
in ocean models.
We have the following fields:
- vertical eddy viscosity (diffusivity of momentum), unit m2 s-1
- vertical eddy diffusivity of tracers, unit m2 s-1
- vertical eddy kinetic energy (per unit mass), unit m2 s-2
- kinetic energy dissipation rate, unit m2 s-3
- mixing length, unit m
Looking at the documentation in [1], I guess for the eddy viscosity and
diffusivity we could use ocean_vertical_momentum_diffusivity and
ocean_vertical_tracer_diffusivity, respectively. But for the other
variables I haven't found a reference.
[1]http://cf-pcmdi.llnl.gov/documents/cf-standard-names/standard-
name-table/16/cf-standard-name-table.html/
Would anyone know if standard names exists for these quantities, and if
so, where they are documented?
Best Regards,
Tuomas Karna
Post-Doctoral Fellow
Center for Coastal Margin Observation and Prediction (CMOP)
Oregon Health and Science University
[email protected]
