Hi all,
volume_fraction_of_ozone_in_air as suggested below is perfect for AIRS. Could
we add to the proposal analogous names for CO and CH4?
volume_fraction_of_carbon_monoxide_in_air (canonical units:1)
' "Volume fraction" is used in the construction volume_fraction_of_X_in_Y,
where X is a material constituent of Y. The chemical formula for carbon
monoxide is CO.'
volume_fraction_of_methane_in_air (canonical units:1)
' "Volume fraction" is used in the construction volume_fraction_of_X_in_Y,
where X is a material constituent of Y. Methane is a member of the group of
hydrocarbons known as alkanes. There are standard names for the alkane group as
well as for some of the individual species. The chemical formula for methane is
CH4.’
-- Evan
----------------------------------------------------------------
Hi Allen,
Thanks for your standard name proposals and thanks to Steve and Roy for the
discussion.
We could introduce names for volume_mixing_ratio as Roy suggests and I am OK
with this if it is your preferred approach. However, I note that where we have
referred to 'mixing_ratio' in other names such as humidity_mixing_ratio and
cloud_liquid_water_mixing_ratio these are actually defined as mass fractions.
Indeed, for chemical species other than H2O we would probably have given them
mass_fraction names.
An alternative to describing your quantities as volume_mixing_ratios would be
to call them volume_fractions. We have many existing mass_fraction and
mole_fraction names for atmospheric quantities and five existing
volume_fraction names for soil water quantities. Whichever names we choose, Roy
is correct that the canonical unit would be simply '1', i.e. these are
dimensionless quantities. You could still specify a unit of 1e-6 or 1e-9 in
your data files as that would be completely compatible with the canonical units.
For existing water vapor quantities we have distinguished between dry and moist
air (humidity_mixing_ratio is the ratio of the mass of water vapor to the mass
of dry air; specific_humidity is the mass fraction of water vapor in moist
air.) You say that your names are for weather balloon data so I assume we are
talking about moist air - we should include that in the definition.
Drawing all this together, my suggestion for your standard names would be:
volume_fraction_of_water_vapor_in_air (canonical units:1)
' "Volume fraction" is used in the construction volume_fraction_of_X_in_Y,
where X is a material constituent of Y. The quantity with standard name
volume_fraction_of_water_vapor_in_air is the volume fraction of water vapor in
moist air.'
volume_fraction_of_ozone_in_air (canonical units:1)
' "Volume fraction" is used in the construction volume_fraction_of_X_in_Y,
where X is a material constituent of Y. The chemical formula for ozone is O3.
The IUPAC name for ozone is trioxygen.'
I appreciate that the information regarding ppmv and ppbv is important for your
data but I suggest that rather than putting it in the standard name, units or
definition, a better approach would be to also include a long_name attribute in
your metadata. This is a non-standardized text string so you could specify
something like the following:
dimensions:
pressure = 100 ;
variables:
float pressure(pressure) ;
pressure:standard_name = "air_pressure" ;
pressure:units = 'Pa' ;
float wv(pressure) ;
wv:standard_name = "volume_fraction_of_water_vapor_in_air " ;
wv:units = "1e-6" ;
wv:long_name = "atmospheric water vapor mixing ratio in parts per million
by volume" ;
float ozone(pressure) ;
ozone:standard_name = "volume_fraction_of_water_vapor_in_air " ;
ozone:units = "1e-9" ;
ozone:long_name = "atmospheric water vapor mixing ratio in parts per
billion by volume" ;
If you could let me know whether you prefer the volume_mixing_ratio or
volume_fraction standard names then I think we can agree these quantities and
put them in the April update to the standard name table.
Best wishes,
Alison
------
Alison Pamment Tel: +44
1235 778065
Centre for Environmental Data Analysis Email:
[email protected]<mailto:[email protected]>
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Campus, Didcot, OX11 0QX, U.K.
From: CF-metadata [mailto:[email protected]] On Behalf Of Lowry,
Roy K.
Sent: 01 March 2017 08:54
To: CF Metadata Mail List
Subject: Re: [CF-metadata] new standard names request
Forgot to set 'reply all'.....
Hi Allen,
As I tried to explain in my last message the way things work in CF is that the
Standard Name is associated with a CANONICAL unit. This is an expression of the
dimensions of the measurement and NOT the actual unit of measure, which is
stored in the NetCDF. For anything in ppt, ppm, ppb etc. the Canonical unit
used is 'dimensionless'.
Cheers, Roy.
Please note that I partially retired on 01/11/2015. I am now only working 7.5
hours a week and can only guarantee e-mail response on Wednesdays, my day in
the office. All vocabulary queries should be sent to
[email protected]<mailto:[email protected]>. Please also use this e-mail
if your requirement is urgent.
________________________________________
From: Allen Jordan - NOAA Affiliate
<[email protected]<mailto:[email protected]>>
Sent: 28 February 2017 22:40
To: Lowry, Roy K.
Cc: Steve Emmerson; CF Metadata Mail List
Subject: Re: [CF-metadata] new standard names request
Hi Roy and Steve. Your modified names will work fine. I would prefer units of
"ppm" and "ppb" as they match our historical naming. I'm very new to the CF
Conventions, please bear with me. Here is the modified request for new fields:
name: volume_mixing_ratio_of_water_vapor_in_air
description: The atmospheric water vapor mixing ratio in parts per million by
volume.
units: ppm
name: volume_mixing_ratio_of_ozone_in_air
description: The atmospheric ozone mixing ratio in parts per billion by volume.
units: ppb
I'll be sure to include the units as attributes of each variable.
Thanks.
- Allen
On Tue, Feb 28, 2017 at 2:40 AM, Lowry, Roy K.
<[email protected]<mailto:[email protected]>> wrote:
Hi Steve,
I think there is a CF precedent would pacify you a little here, which is to
have Standard Names of the form 'volume_mixing_ratio' with canonical units of
dimensionless such as volume_mixing_ratio_of_oxygen_at_stp_in_sea_water. I
would suggest following this practice in this case with:
volume_mixing_ratio_of_water_vapor_in_air
volume_mixing_ratio_of_ozone_in_air
A note to Allen is that your actual units including scaling factor are
explicity included in CF NetCDF as a parameter attribute.
Cheers, Roy.
Please note that I partially retired on 01/11/2015. I am now only working 7.5
hours a week and can only guarantee e-mail response on Wednesdays, my day in
the office. All vocabulary queries should be sent to
[email protected]<mailto:[email protected]>. Please also use this e-mail
if your requirement is urgent.
________________________________________
From: CF-metadata
<[email protected]<mailto:[email protected]>> on
behalf of Steve Emmerson <[email protected]<mailto:[email protected]>>
Sent: 27 February 2017 22:04
To: Allen Jordan - NOAA Affiliate
Cc: CF Metadata Mail List
Subject: Re: [CF-metadata] new standard names request
BEGIN RANT
This is the kind of stuff that I don't like: putting additional (and
unnecessary) semantics into the unit specification. "ppm" is bad enough (1e-6
would be better) but *volume*!
The attributes of a physical quantity are attributes of the quantity itself --
*not* its unit. If a physical quantity is atmospheric mixing ratio by volume,
then name it as such and leave the unit alone. The alternative is to pollute
the unit namespace with "volume", "mass", "carbon", and whatever else people
think up -- leading to a unending additions to the units database.
Call the quantity "atmospheric water vapor mixing ratio by volume" and specify
the unit as "1e-6" (or "ppm" if you must).
Lest you think I'm alone in this, see sections 7.4 and 7.5 of
<https://www.nist.gov/pml/nist-guide-si-chapter-7-rules-and-style-conventions-expressing-values-quantities>.
NIST Guide to the SI, Chapter 7: Rules and Style ...
www.nist.gov
7.1 Value and numerical value of a quantity The value of a quantity is its
magnitude expressed as the product of a number and a unit, and the number
multiplying the ...
END RANT
Thanks for letting me get this off my chest. :-)
Regards,
Steve Emmerson
On Mon, Feb 27, 2017 at 2:21 PM, Allen Jordan - NOAA Affiliate
<[email protected]<mailto:[email protected]>> wrote:
I would like to add two standard names for the NOAA GMD OZWV group's weather
balloon data:
name: water_vapor_mixing_ratio
description: The atmospheric water vapor mixing ratio in parts per million by
volume.
units: ppmv
name: ozone_mixing_ratio
description: The atmospheric ozone mixing ratio in parts per billion by volume.
units: ppbv
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