Dear all,
thank you for all your answers. Below we have tried to incorporate the remarks
from the mailing list replies to our original email as well as the other emails
about the aerosol standard names proposed by Markus Fiebig.
1) "vertical_speed":
We suggest to change the name to "platform_upward_vertical_speed_wrt_sea_level".
name:
platform_upward_vertical_speed_wrt_sea_level
unit:
m s-1
definition
Standard names for platform describe the motion and orientation of the vehicle from which
observations are made e.g. aeroplane, ship or satellite. The platform vertical speed is
the rate of change of platform altitude. "Upward" indicates a vector component
which is positive when directed upward (negative downward). Speed is the magnitude of
velocity. sea_level means mean sea level, which is close to the geoid in sea areas.
2) "total_air_temperature":
We agree it should be called "stagnation_air_temperature" instead.
name:
stagnation_air_temperature
unit:
K
definition:
Stagnation air temperature is the temperature at a stagnation point in a fluid
flow. At a stagnation point the speed of the fluid is zero and all of the
kinetic energy has been converted to internal energy (adiabatically) and is
added to the local static enthalpy. In incompressible fluid flow, and in
isentropic compressible flow, the stagnation temperature is equal to the total
temperature at all points on the streamline leading to the stagnation point.
3) "size_resolved_number_concentration_of_dry_aerosol_in_air":
We retract this proposal since Markus has already proposed
"distribution_of_number_concentration_of_dried_aerosol_particle_size_at_stp_in_air"
In the definition of this, we would need a small addition since we measure the
particle sizes by optical means. So we suggest to change the last part of the
definition to:
A coordinate variable needs to be specified which indicates in which way the particle sizes are
determined. Examples for this are "electrical_mobility_particle_diameter" or
"optical_spherical_particle_diameter".
This would then require the following additional standard names which we
suggest for inclusion into the CF standard name table:
3a) "optical_spherical_particle_diameter"
unit:
m
definition:
The diameter of a particle determined from the scattered light assuming Mie scattering theory and a spherical
particle shape. Scalar coordinate variables for the refractive index of the particles used in the Mie
calculations should be given the standard names "particle_refractive_index_real_part" and
"particle_refractive_index_imaginary_part". A scalar coordinate variable for radiation wavelength
should be given the standard name "radiation_wavelength".
3b) particle_refractive_index_real_part
unit:
1
definition:
Real part of the refractive index
3c) particle_refractive_index_imaginary_part
unit:
1
definition:
Imaginary part of the refractive index
4) "size_resolved_number_concentration_of_cloud_liquid_water_particles_in_air"
following 3) we suggest to change this to
"distribution_of_number_concentration_of_cloud_liquid_water_particle_size_at_stp_in_air"
name:
distribution_of_number_concentration_of_cloud_liquid_water_particle_size_at_stp_in_air
unit:
m-3
definition:
The particle number size distribution is the number concentration of cloud droplets (excluding ice particles)
per decadal logarithmic size interval as a function of particle diameter. Cloud droplets are spherical and
typically a few micrometers to a few tens of micrometers in diameter. An upper limit of 0.2 mm diameter is
sometimes used to distinguish between cloud droplets and drizzle drops, but in active cumulus clouds strong
updrafts can maintain much larger cloud droplets. "at_stp" refers to a volume at standard
conditions of temperature (273.15 K) and pressure (1013.25 hPa). A coordinate variable needs to be specified
which indicates in which way the particle sizes are determined. Examples for this are
"electrical_mobility_particle_diameter" or "optical_spherical_particle_diameter".
5) "particle_surface_area_concentration_of_dry_aerosol_in_air"
there has been no comments to this or did we miss it ?
Following 3) and 4), we suggest to change this to:
"particle_surface_area_concentration_of_dried_aerosol_particles_at_stp_in_air"
name:
particle_surface_area_concentration_of_dried_aerosol_particles_at_stp_in_air
unit:
m-1 (was wrong in our original proposal since it is area per volume, i.e.
m2/m3 = m-1
definition:
The particle surface area concentration is the total surface of the aerosol particles per volume. "Aerosol" means the suspended
liquid or solid particles in air (except cloud droplets). "Dried_aerosol" means that the aerosol sample has been dried from the
ambient state, but that the dry state (RH < 40%) hasn't necessarily been reached. To specify the relative humidity at which the property
applies, provide scalar coordinate variable with the standard name of "relative_humidity". "at_stp" refers to a volume at
standard conditions of temperature (273.15 K) and pressure (1013.25 hPa). A coordinate variable needs to be specified which indicates in which
way the particle sizes are determined. Examples for this are "electrical_mobility_particle_diameter" or
"optical_spherical_particle_diameter".
In addition to our original proposal, we would like to propose yet another
aerosol particle standard name:
6)
"distribution_of_number_concentration_of_nonvolatile_aerosol_particle_size_at_stp_in_air":
name:
distribution_of_number_concentration_of_nonvolatile_aerosol_particle_size_at_stp_in_air
unit:
m-3
definition:
The particle number size distribution is the number concentration of nonvolatile aerosol particles per decadal logarithmic size
interval as a function of particle diameter. "Aerosol" means the suspended liquid or solid particles in air (except
cloud droplets). To specify the temperature up to which the particles are non-volatile, a scalar coordinate variable with the
standard name of "temperature" should be provided. "at_stp" refers to a volume at standard conditions of
temperature (273.15 K) and pressure (1013.25 hPa). A coordinate variable needs to be specified which indicates in which way the
particle sizes are determined. Examples for this are "electrical_mobility_particle_diameter" or
"optical_spherical_particle_diameter".
In our case we talk about generally solid particles which are non-volatile after having passed a
250°C thermo denuder. But even mineral particles would melt and being "liquid particles"
at high enough temperatures, therefore we are not more specific here when defining the term
"Aerosol".
Did we miss any other important points in the definitions ?
Best regards,
Damien
On 18/09/14 23:04, Markus Fiebig wrote:
Hi Damien,
thanks for taking the initiative on behalf of IGAS!
I was looking through your list of proposed standard names and compared it to
those I had proposed earlier as an initiative of the WMO GAW Scientific Advisory
Group for Aerosol. Due to the process of iterating this list of names between 3
different bodies, the GAW SAG list hasn't been finally accepted here yet, but we
are fairly close, so we should make sure the 2 lists are aligned. I had
previously proposed the following names:
1. number_size_distribution_of_dried_aerosol_particles_at_stp_in_air
The particle number size distribution is the number concentration of
aerosol
particles per decadal logarithmic size interval as a function of particle
diameter. "Aerosol" means the suspended liquid or solid particles in air
(except cloud droplets). "Dried_aerosol" means that the aerosol sample has
been dried from the ambient state, but that the dry state (RH < 40%) hasn't
necessarily been reached. To specify the relative humidity at which the
property applies, provide scalar coordinate variable with the standard name
of "relative_humidity". "at_stp" refers to a volume at standard conditions
of temperature (273.15 K) and pressure (1013.25 hPa). A coordinate variable
of "electrical_mobility_particle_diameter" needs to be specified to
indicate
that the property applies at specific particle sizes.
2. number_size_distribution_of_cloud_condensation_nuclei_at_stp_in_air
The cloud condensation nuclei number size distribution is the number
concentration of aerosol particles per decadal logarithmic size interval as
a function of particle diameter that act as condensation nuclei for
liquid-phase clouds. "Aerosol" means the suspended liquid or solid
particles
in air (except cloud droplets). "Dried_aerosol" means that the aerosol
sample has been dried from the ambient state before sizing, but that the
dry
state (RH < 40%) hasn't necessarily been reached. To specify the relative
humidity at which the sample was sized, provide scalar coordinate variable
with the standard name of "sizing_relative_humidity". "at_stp" refers to a
volume at standard conditions of temperature (273.15 K) and pressure
(1013.25 hPa). Coordinate variables of
"electrical_mobility_particle_diameter" and "relative_humidity" need to be
specified to indicate that the property refers to specific particle sizes
and supersaturations with respect to liquid water.
Those names don't align with the ones you proposed in a few aspects. In the
discussion of these names, we discovered that we need to be textbook strict and
unambiguous when using the term "aerosol" (system of particles and carrier gas).
That's why the iterated names use "aerosol_particles" to be precise and avoid
confusion. Also, from the definition of your names, I have difficulty
understanding what precisely you mean with "size_resolved_number_concentration".
Is this a number size distribution, or a set of number concentrations of
particles in defined size intervals? Size distributions are commonly normalised
by the decadal logarithmic size interval applicable for each size bin. That way,
it is possible to state the size distribution with only one coordinate variable
in particle diameter. To state the particle number concentration as such for
defined particle diameter bins is rather unusual. You would need 2 coordinate
variables (upper and lower particle diameter limiting each size bin) to be
precise. In the discussion of the GAW SAG names, we also touched upon the issue
how the particle diameter is determined. The result usually depends on the
measurement method used. To be precise, you would need a coordinate variable
such as "optical_particle_diameter".
Best regards,
Markus
Am 18.09.2014 01:08, schrieb John Graybeal:
Hi Jörg,
Thanks for clarifying the units. I agree with the semantic concern you raise
about the names. I couldn't make the description fit the name terminology
after several attempts, but I am a novice in that domain.
Regarding " the tradition in the CF community to combine variable and matrix
or platform", could you describe what you mean by this? I don't know which
terms are combining matrix or platform -- platform for example only (?) comes
into play when the measurement is of a platform and its characteristics, and
I'm guessing you'll agree that this needs to be kept distinct from
measurements of ambient conditions in the environment.
John
On Sep 17, 2014, at 09:00, [email protected]
<mailto:[email protected]> wrote:
Hi Damien and colleagues
The units for the number concentrations are okay IMHO, it's particles per
volume, so 1/m^3 or m-3 should be right. I agree with John's comment on
vertical velocity, to specify a direction makes sense. I have a problem with
the "size_resolved_number_concentration_" terminology, which I have always
had but comment on here for the first time: I find it not very telling and
semantically wrong. In my understanding, the term should be more sth like
"size_spectrum_of_number_concentration_".
A more general concern I have (with the plethora of
variable/matrix/platform/size-cutoffs in GAW in mind) is the tradition in the
CF community to combine variable and matrix or platform. From a data
management point of view, combining various dimensions is what one rather
tries to avoid as the number of possible permutations makes code lists grow
tremendously long. A better approach would be to develop codelists for the
individual dimensions and then draw from those. I am not sure a consensus on
this view will be found, though.
Kind regards
Jörg
_________________________________
*Dr. Jörg Klausen*
Measurements and Data Department
Federal Department of Home Affairs FDHA
*Federal Office of Meteorology and Climatology MeteoSwiss*
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All about GAW observations at
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*From:*John Graybeal [mailto:[email protected]]
*Sent:*Dienstag, 16. September 2014 18:22
*To:*Damien Boulanger
*Cc:*CF Metadata List; Armin Rauthe-Schöch; Martin Schultz; Klausen Jörg
*Subject:*Re: [CF-metadata] IAGOS-CARIBIC parameters
Hi Damien,
You've started the process nicely. What happens next is that various people
on the list comment on your names and definitions, and the process continues
until consensus is reached. Don't feel obligated to respond to every post,
just join in as you find it appropriate. (If your colleagues want to follow
all the posts, they'll want to be subscribed to the list.)
I'll kick it off with a few comments on the more 'generic' terms.
vertical_speed probably needs to be more specific, since most terms capture
both the aubstance or object (in this case the airplane) and the process.
Following the other platform terms, I suggest naming this
platform_vertical_speed. (it isn't clear whether this is a directional speed,
e.g., negative numbers are down? If so then platform_upward_vertical_speed
would be better.) The definition should reflect these changes, and will
include the stock phrase "Speed is the magnitude of velocity." Also, the
canonical units for this item need to be distance/time, so m s-1.
Your description of total_air_temperature sounds like the stagnation is the
key point of this measurement. I would propose stagnant_air_temperature as a
starting point. And, it seems this measurement may be as much about the
platform as about the air itself (if the stagnation is caused by the
platform); perhaps this should be included in the name, to distinguish from
an environmentally stagnant patch of air. That name could be
stagnant_air_temperature_due_to_platform, for example.
One other comment about units, the units for the first 3 terms may be off.
For a volume you'd want m3 (cubed m) not m-3 (1 over cubed m), but the
description doesn't seem like a volume. Other people with more expertise on
this topic can chime in here.
John
------------------------------------
*John Graybeal*
Marine Data Manager
M +1 408 675-5445
Marinexplore
On Sep 16, 2014, at 00:20, Damien Boulanger <[email protected]
<mailto:[email protected]>> wrote:
Dear all,
within the frame of the IGAS project (IAGOS for Copernicus Atmospheric
Service,http://www.igas-project.org
<http://www.igas-project.org/index.php/ProjectInfo/ProjectInformation>) we
would like to propose 5 new CF standard names:
*standard_name*
*units*
*definition*
size_resolved_number_concentration_of_dry_aerosol_in_air
m-3
Size resolved denotes the capability of an instrument to measure aerosol
properties in different size ranges. The size range of particles is typically
given as a range of particle diameters in nm assuming spherical shape and
must be provided in a comment attribute. Number concentration means the
number of particles or other specified objects per unit volume. "Aerosol"
means the suspended liquid or solid particles in air (except cloud droplets).
"Dry aerosol" means aerosol without water.
particle_surface_area_concentration_of_dry_aerosol_in_air
m-3
Surface area per volume derived from the size resolved particle number
concentration. "Aerosol" means the suspended liquid or solid particles in air
(except cloud droplets). "Dry aerosol" means aerosol without water.
size_resolved_number_concentration_of_cloud_liquid_water_particles_in_air
m-3
Size resolved denotes the capability of an instrument to measure aerosol
properties in different size ranges. The size range of particles is typically
given as a range of particle diameters in nm assuming spherical shape and
must be provided in a comment attribute. Number concentration means the
number of particles or other specified objects per unit volume. Cloud
droplets are spherical and typically a few micrometers to a few tens of
micrometers in diameter. An upper limit of 0.2 mm diameter is sometimes used
to distinguish between cloud droplets and drizzle drops, but in active
cumulus clouds strong updrafts can maintain much larger cloud droplets.
vertical_speed
1
Rate of change of aircraft altitude.
total_air_temperature
K
Total air temperature or stagnation temperature is the temperature at a
stagnation point in a fluid flow. Measured by a temperature probe mounted on
the surface of the aircraft.
I'm not really sure what is the standard procedure. Let me know if you need
any more information.
Best regards,
Damien Boulanger and the IGAS team
--
Damien Boulanger
CNRS - UMS831 OMP - SEDOO
Observatoire Midi-Pyrénées
14 Avenue Edouard Belin 31400 Toulouse - France
Phone: (+33) 05-61-33-27-71
Email: [email protected] <mailto:[email protected]>
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Dr. Markus Fiebig
Senior Scientist
Dept. Atmospheric and Climate Research (ATMOS)
Norwegian Institute for Air Research (NILU)
P.O. Box 100
N-2027 Kjeller
Norway
Tel.: +47 6389-8235
Fax : +47 6389-8050
e-mail: [email protected]
skype: markus.fiebig
P Please consider the environment before printing this email and attachments
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CNRS - UMS831 OMP - SEDOO
Observatoire Midi-Pyrénées
14 Avenue Edouard Belin 31400 Toulouse - France
Phone: (+33) 05-61-33-27-71
Email: [email protected]
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