Dear Craig, Jonathan and all contributors to this thread,
I have changed the subject line back to the original, just to underline
that there is a separation between the more fundamental discussion of
'what standard names are for' and the specific set of proposals for SST
names.
It seems that we now have agreement on the following names:
surface_temperature
sea_water_temperature (for temperatures at depth)
sea_surface_skin_temperature
sea_surface_subskin_temperature
sea_surface_foundation_temperature
The first two are already in the standard name table. The remaining
three will be added to the table at the next update on 13th May 2008.
The definition of surface_temperature will be modified very slightly to
remove the parenthesised word "(skin)". The three new names will
closely follow the GHRSST definitions at
https://www.ghrsst-pp.org/SST-Definitions.html. Craig, can you please
confirm that you are happy with the wording of the following:
sea_surface_skin_temperature:
The surface called "surface" means the lower boundary of the atmosphere.
The sea surface skin temperature is the temperature measured by an
infrared radiometer typically operating at wavelengths in the range 3.7
- 12 micrometers. It represents the temperature within the conductive
diffusion-dominated sub-layer at a depth of approximately 10 - 20
micrometers below the air-sea interface. Measurements of this quantity
are subject to a large potential diurnal cycle including cool skin layer
effects (especially at night under clear skies and low wind speed
conditions) and warm layer effects in the daytime.
sea_surface_subskin_temperature:
The surface called "surface" means the lower boundary of the atmosphere.
The sea surface subskin temperature is the temperature at the base of
the conductive laminar sub-layer of the ocean surface, that is, at a
depth of approximately 1 - 1.5 millimeters below the air-sea interface.
For practical purposes, this quantity can be well approximated to the
measurement of surface temperature by a microwave radiometer operating
in the 6 - 11 gigahertz frequency range, but the relationship is neither
direct nor invariant to changing physical conditions or to the specific
geometry of the microwave measurements.
sea_surface_foundation_temperature:
The surface called "surface" means the lower boundary of the atmosphere.
The sea surface foundation temperature is the temperature of the water
column free of diurnal temperature variability (daytime warming or
nocturnal cooling) and is considered equivalent to the quantity with
standard name sea_surface_subskin_temperature in the absence of any
diurnal signal. It is named to indicate that it is the foundation
temperature from which the growth of the diurnal thermocline develops
each day (noting that on some occasions with a deep mixed layer there is
no clear foundation temperature profile in the surface layer), that is,
sea surface foundation temperature is measured at the base of the
diurnal thermocline. Only in situ contact thermometry is able to
measure sea surface foundation temperature and analysis procedures must
be used to estimate the its value from radiometric satellite
measurements of the quantities with standard names
sea_surface_skin_temperature and sea_surface_subskin_temperature. Sea
surface foundation temperature provides a connection with the historical
concept of a "bulk" sea surface temperature (SST) considered
representative of the oceanic mixed layer temperature and represented by
any sea temperature measurement within the upper ocean over a depth
range of 1 to approximately 20 meters. The "bulk" SST has the standard
name sea_surface_temperature. For the temperature of sea water at a
particular depth or layer, a data variable of sea_water_temperature with
a vertical coordinate axis should be used. Sea surface foundation
temperature provides a more precise, well-defined quantity than "bulk"
SST and, consequently, is more representative of the mixed layer
temperature. In general, sea surface foundation temperature will be
similar to a night time minimum or pre-dawn value at depths of between
approximately 1 and 5 meters, but some differences could exist. Note
that this quantity does not imply a constant depth mixed layer, but
rather a surface layer of variable depth depending on the balance
between stratification and turbulent energy and is expected to change
slowly over the course of a day.
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
<mailto:J.A.Pamment at rl.ac.uk>
Chilton, Didcot, OX11 0QX, U.K.
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Received on Wed Apr 30 2008 - 05:47:03 BST
