Hi Allison, Paul, Roy, et al.,
I would suggest to replace the 3rd sentence
"The partial pressure of a gaseous constituent of air is the pressure which it
alone would exert with unchanged temperature and number of moles per unit
volume."
with the following:
"The partial pressure of a gaseous constituent of air is the pressure that it
would exert if all other gaseous constituents were removed, assuming the volume,
the temperature, and its number of moles remain unchanged."
The description would then become as follows:
'The fugacity is the measured pressure (or partial pressure) of a real gas
corrected for the intermolecular forces of that gas, which allows that corrected
quantity to be treated like the pressure of an ideal gas in the ideal gas
equation PV = nRT. The partial pressure of a dissolved gas in sea water is the
partial pressure in air with which it would be in equilibrium. The partial
pressure of a gaseous constituent of air is the pressure that it would exert if
all other gaseous constituents were removed, assuming the volume, the
temperature, and its number of moles remain unchanged. The chemical formula for
carbon dioxide is CO2.'
In addition, is the last sentence useful given that it is common knowledge?
Thanks,
Jim
On Thu, 4 Oct 2018, Alison Pamment - UKRI STFC wrote:
Dear Paul,
Thank you for proposing this new standard name and thanks also to Roy, Jim and
Jonathan for their comments.
I think the proposal as it now stands is:
fugacity_of_carbon_dioxide_in_sea_water (Canonical units: Pa)
'The fugacity is the measured pressure (or partial pressure) of a real gas
corrected for the intermolecular forces of that gas, which allows that
corrected quantity to be treated like the pressure of an ideal gas in the ideal
gas equation PV = nRT. The partial pressure of a dissolved gas in sea water is
the partial pressure in air with which it would be in equilibrium. The partial
pressure of a gaseous constituent of air is the pressure which it alone would
exert with unchanged temperature and number of moles per unit volume. The
chemical formula for carbon dioxide is CO2.'
Paul, please can you confirm if this is all okay? If so, I think the name can
be accepted and included in the next update to the table.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/Centre for Environmental Data Archival Email: [email protected]
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
-----Original Message-----
From: CF-metadata <[email protected]> On Behalf Of Halloran, Paul
Sent: 26 September 2018 12:59
To: [email protected]
Subject: Re: [CF-metadata] New name: fugacity of CO2
Thanks very much Jim.
Just to clarify (in light of Jim’s second point), my argument around air-sea
CO2 flux which I put forward to support my suggestion that we include fugacity
is that an imprecise conversion from fugacity of CO2 to pCO2 to allow one to
submit data as a compliant netcdf (due to potentially not having the the other
required variables available at the correct frequency), while likely to only
result in small numerical errors could have bigger implications if then used to
calculate air-sea CO2 flux.
Thanks,
Paul
Hi Paul, Roy, et al.,
A couple of points regarding fugacity.
1) In the proposed definition of fugacity, the first sentence could be
misunderstood. I suggest changing it to the following:
The fugacity is the measured pressure (or partial pressure) of a real
gas corrected for the intermolecular forces of that gas, which allows
that corrected quantity to be treated like the pressure of an ideal
gas in the ideal gas equation PV = nRT.
2) The air-sea flux of a gas does not depend on its fugacity, only its
partial pressure (i.e., in both the atmosphere and ocean).
Cheers,
Jim
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