Dear Craig and all those who have contributed to this thread,
Thank you to all of you for your many valuable contributions during this
discussion.
I have reviewed the whole SST thread from the beginning and it is clear
that there is widespread support for the GHRSST definitions and the need
to describe each of them individually with a CF standard name.
I would like to clarify one procedural point arising from Craig's last
posting, which is that I do not, in fact, have a casting vote. My role
is to follow all the standard names discussions, suggest possible
clarifications to proposed names and/or definitions and to moderate the
mailing list discussions with the aim of achieving consensus. Any
decision that is reached regarding any of the standard names must be
firmly based on the points raised during the mailing list discussion.
Moving now to the details of the standard names, the following gives the
current status of each of the proposals.
1. GHRSST name SSTdepth
There is unanimous agreement to use the existing CF standard name
sea_water_temperature accompanied by a scalar vertical coordinate
variable to record the depth.
2. GHRSST names skin_layer_sea_surface_temperature and
sub_skin_sea_surface_temperature
There is widespread support for the CF standard names to include
explicitly the words "skin" and "subskin". Jonathan has suggested the
wording sea_skin_temperature and sea_subskin_temperature on the grounds
that "skin" and "subskin" are not, strictly speaking, the same concept
as "surface". Olivier has supported Jonathan's suggestion and Craig has
indicated that he is content to accept this approach. There have been no
objections to this suggestion. Thus, sea_skin_temperature and
sea_subskin_temperature are accepted as new standard names. They will
be included in the table update scheduled for May.
If the need arises to state precisely the wavelength at which
sea_skin_temperature or sea_subskin_temperature were measured, a scalar
coordinate variable with the standard name radiation_wavelength could be
supplied as additional metadata.
3. GHRSST name interface_sea_surface_temperature
I suggested that the existing standard name surface_temperature could be
used for this quantity. This suggestion has received support from
Olivier and qualified support from Roy. Craig has indicated that he
finds this solution acceptable.
After some further consideration I think that the definition of the
existing name should be modified slightly. The definition currently
reads:
"The surface called 'surface' means the lower boundary of the
atmosphere. The surface temperature is the (skin) temperature at the
interface, not the bulk temperature of the medium above or below."
I suggest that the parenthesised word "skin" be deleted to avoid any
potential confusion with the new name 'sea_skin_temperature'. In all
other respects I think that the existing definition matches the GHRSST
definition supplied by Craig:
"At the exact air-sea interface a hypothetical temperature called the
interface temperature (SSTint) is defined although this is of no
practical use because it cannot be measured using current technology."
I don't think that deleting "skin" from the definition will affect the
meaning of surface_temperature as used in coupled models, where it is
the temperature that is seen by physics parametrizations such as the
longwave radiation.
4. GHRSST name SSTfnd (foundation temperature)
The only issue remaining to be resolved is the precise wording of the
name. There are currently two options on the table:
sea_surface_temperature_at_diurnal_thermocline_base and
sea_foundation_temperature.
I suggested the former as a way of trying to encapsulate the meaning of
the name using widely understood terminology. Jonathan has supported
the suggestion. Craig has raised the point that foundation_temperature
has been widely adopted within the data assimilation community and is in
daily use.
I have changed my mind about this name and actually I now prefer
sea_foundation_temperature over my original suggestion. Given that we
have achieved consensus for sea_skin_temperature and
sea_subskin_temperature I think that sea_foundation_temperature provides
a concise and consistent syntax. Additionally, the argument that "skin"
and "subskin" are not the same as the physical sea surface could equally
well be applied to "foundation"/"base_of_diurnal_thermocline" so it
would seem inconsistent to refer to this quantity as a
"sea_surface_temperature". It is true that "foundation" is a new term
to standard names, but actually so are "skin" and "subskin" so, all
things considered, I can't see any reason to treat this name
differently. Last, but not least, sea_foundation_temperature has the
advantage of using a term that is well recognized in the GHRSST
community. Jonathan, do you think this sounds reasonable?
One general comment: in his posting
http://www.cgd.ucar.edu/pipermail/cf-metadata/2008/002066.html, Craig
raised the issue of CF long_names. The long_names are not standardised
in any way, so this attribute can be used to include any alternative
name that is meaningful to the GHRSST community. For example, the CF
long name could contain the GHRSST "shorthand" names such as 'SSTdepth',
'SSTint', etc., if that would be a useful thing to do.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre Fax: +44 1235 446314
Rutherford Appleton Laboratory Email: J.A.Pamment at rl.ac.uk
Chilton, Didcot, OX11 0QX, U.K.
Received on Fri Apr 04 2008 - 06:09:46 BST
