[CF-metadata] new standard names for surface aerosol optical properties

Cameron-smith, Philip cameronsmith1 at llnl.gov
Fri Sep 21 19:27:51 MDT 2012


Hi Markus,



I apologize for not responding sooner.  I have been tied up in reviews and things.



I don't think anyone else has responded yet to your email prompt last month.



I like your proposal for "_due_to_dried_aerosol".  It seems to address all the concerns on that point.



However, I had some other concerns (my email March 9, 2012) that I don't think have been resolved yet: please correct me if I'm wrong.



1) I am not sure what you mean by "surface_volume_", since a surface is infinitesimally thin.  Do you mean _volume_ of air near the surface?  If so, couldn't that be done using the vertical coordinate and avoiding a whole lot of "surface_" std_names?   Or, am I misunderstanding something fundamental?



2) You appear to have changed from _hemispheric_backscattering_ to _spherical_backscattering_.

However, this appears to be the same definition that is already given to both _backscattering_  and _backwards_scattering_ (see examples below), which are integrated over angle (according to their descriptions).  Although it is confusing because the units for some of the existing std_names use Sr-1, and some don't, so there maybe inconsistency in the existing table. In summary, I am resistant to adding either of your new terms unless we determine that neither old term will work.



Hopefully one of the original proposers of those terms is still on the list and can clarify what is going on with the existing scattering std_names&units.  I have attached a screenshot of those terms below.



Best wishes,



     Philip



[cid:image001.png at 01CD9826.1826D630]



-----------------------------------------------------------------------

Dr Philip Cameron-Smith, pjc at llnl.gov, Lawrence Livermore National Lab.

-----------------------------------------------------------------------







> -----Original Message-----

> From: Markus Fiebig [mailto:Markus.Fiebig at nilu.no]

> Sent: Thursday, August 16, 2012 7:36 AM

> To: Markus Fiebig; Cameron-smith, Philip; John Graybeal

> Cc: cf-metadata at cgd.ucar.edu; alison.pamment at stfc.ac.uk

> Subject: RE: [CF-metadata] new standard names for surface aerosol optical

> properties

>

> Dear all,

>

> with the summer holidays coming to an end, it should be time to sum up the

> proposed addition to the CF standard names list. On my last post (see below),

> which was discussed  in depth before, I received one reply by Jonathan, which

> was positive, and no objections. Can we thus consider this proposal as accepted

> and ready for being added to the official list on its next update?

>

> Best regards,

> Markus

>

> _______________________________________

> Dr. Markus Fiebig

>

> 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: Markus.Fiebig at nilu.no<mailto:Markus.Fiebig at nilu.no>

> skype: markus.fiebig

>

>

> -----Original Message-----

> From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu]<mailto:[mailto:cf-metadata-bounces at cgd.ucar.edu]> On Behalf Of

> Markus Fiebig

> Sent: Samstag, 16. Juni 2012 22:11

> To: Cameron-smith, Philip; John Graybeal

> Cc: cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>

> Subject: Re: [CF-metadata] new standard names for surface aerosol optical

> properties

>

> Dear Philip, John, and all,

>

> after discussing this issue also offline with a few peers, and including the

> comments of Philip and John, I think I can propose a solution:

>

> The original problem:

> CF aerosol variable names so far use the terms "_due_to_ambient_aerosol" and

> "due_to_dry_aerosol". For variables with "_due_to_ambient_aerosol", a co-

> ordinate variable relative_humidity is required since most aerosol properties are

> strongly dependent on particle humidification, and not taking this effect into

> account would render any model-observation comparison meaningless. The

> observations of surface aerosol optical properties I'm concerned with are

> intended to be on the dry aerosol. In some locations however (e.g. in the

> tropics), sample drying can be incomplete at times, leaving the sample in a state

> between ambient and dry. In practice, these data would be used for

> comparisons in the same way as those with "_due_to_ambient_aerosol", where

> the humidity state needs to be taken into account, except that the humidity is

> neither ambient nor dry.

>

> The proposed solution:

> I propose to introduce "_due_to_dried_aerosol" as third term besides

> "_due_to_ambient_aerosol" and "due_to_dry_aerosol". The definitions using

> this term would say that a drying procedure has been applied to the sample, but

> that the dry aerosol state (RH < 40%) may or may not have been reached

> completely. I asked a few English native speakers, and most of them said this

> definition was what they thought when hearing the term, even without knowing

> the definition. Using "_due_to_dried_aerosol" would require a co-ordinate

> variable "relative_humidity".

> The term "_due_to_dried_aerosol" has the advantage of conveying how the

> measurement was obtained while being comparatively short. The term should

> also transport the information that Philip and John intended with their proposed

> solutions.

>

> Below, you find a complete updated list of the standard names I proposed,

> including definitions. Even though I'm happy about further comments on the

> proposal, I think we are close to a conclusion of this discussion, and I would like

> to thank all discussion participants for their contributions so far!

>

> Best regards,

> Markus

>

> ---------------------------------------------------------------------------

> Updated list of proposed standard names (2012-06-16)

>

> 1) volume_scattering_coefficient_in_air_due_to_dry_aerosol

>

> The volume scattering coefficient is the fractional change of radiative flux per

> unit path length due to redirection of an incident light beam by a component in

> the reference volume. "Aerosol" means the suspended liquid or solid particles in

> air (except cloud droplets). Aerosol takes up ambient water (a process known as

> hygroscopic growth) depending on the relative humidity and the composition of

> the aerosol. "Dry aerosol" means aerosol fully dehydrated from its ambient

> state, which in practice often means brought to a relative humidity less than

> 40%. The specification of a physical process by the phrase "due_to_" process

> means that the quantity named is a single term in a sum of terms which together

> compose the general quantity named by omitting the phrase. A coordinate

> variable of radiation_wavelength or radiation_frequency needs to be specified

> to indicate that the property applies at specific wavelengths or frequencies.

>

>

> 2) volume_absorption_coefficient_in_air_due_to_dry_aerosol

>

> The volume absorption coefficient is the fractional change of radiative flux per

> unit path length due to absorption of an incident light beam by a component in

> the reference volume. "Aerosol" means the suspended liquid or solid particles in

> air (except cloud droplets). Aerosol takes up ambient water (a process known as

> hygroscopic growth) depending on the relative humidity and the composition of

> the aerosol. "Dry aerosol" means aerosol fully dehydrated from its ambient

> state, which in practice often means brought to a relative humidity less than

> 40%. The specification of a physical process by the phrase "due_to_" process

> means that the quantity named is a single term in a sum of terms which together

> compose the general quantity named by omitting the phrase. A coordinate

> variable of radiation_wavelength or radiation_frequency needs to be specified

> to indicate that the property applies at specific wavelengths or frequencies.

>

>

> 3) volume_spherical_backscattering_coefficient_in_air_due_to_dry_aerosol

>

> The volume spherical backscattering coefficient is the fractional change of

> radiative flux per unit path length due to redirection of an incident light beam

> into the rearward hemisphere relative to the incident beam by a component in

> the reference volume. It is distinct from the backscattering coefficient which

> isn't integrated over the rearward hemisphere. "Aerosol" means the suspended

> liquid or solid particles in air (except cloud droplets). Aerosol takes up ambient

> water (a process known as hygroscopic growth) depending on the relative

> humidity and the composition of the aerosol. "Dry aerosol" means aerosol fully

> dehydrated from its ambient state, which in practice often means brought to a

> relative humidity less than 40%. The specification of a physical process by the

> phrase "due_to_" process means that the quantity named is a single term in a

> sum of terms which together compose the general quantity named by omitting

> the phrase. A coordinate variable of radiation_wavelengt  h or

> radiation_frequency needs to be specified to indicate that the property applies

> at specific wavelengths or frequencies.

>

>

> 4)

> surface_volume_scattering_coefficient_at_stp_in_air_due_to_pm1_dry_aeroso

> l

>

> The volume scattering coefficient is the fractional change of radiative flux per

> unit path length due to redirection of an incident light beam by a component in

> the reference volume. "Aerosol" means the suspended liquid or solid particles in

> air (except cloud droplets). Aerosol takes up ambient water (a process known as

> hygroscopic growth) depending on the relative humidity and the composition of

> the aerosol. "Dry aerosol" means aerosol fully dehydrated from its ambient

> state, which in practice often means brought to a relative humidity less than

> 40%. The specification of a physical process by the phrase "due_to_" process

> means that the quantity named is a single term in a sum of terms which together

> compose the general quantity named by omitting the phrase. "surface" means

> the lower boundary of the atmosphere. "at_stp" refers to a volume at standard

> conditions of temperature (273.15 K) and pressure (1013.25 hPa). "pm1" refers

> to the fraction of aerosol particles with an aero  dynamic diameter of less than

> or equal to 1 micrometer, where the size cut is applied under ambient conditions

> before the aerosol is dried. A coordinate variable of radiation_wavelength or

> radiation_frequency needs to be specified to indicate that the property applies

> at specific wavelengths or frequencies.

>

>

> 5)

> surface_volume_scattering_coefficient_at_stp_in_air_due_to_pm10_dry_aeros

> ol

>

> The volume scattering coefficient is the fractional change of radiative flux per

> unit path length due to redirection of an incident light beam by a component in

> the reference volume. "Aerosol" means the suspended liquid or solid particles in

> air (except cloud droplets). Aerosol takes up ambient water (a process known as

> hygroscopic growth) depending on the relative humidity and the composition of

> the aerosol. "Dry aerosol" means aerosol fully dehydrated from its ambient

> state, which in practice often means brought to a relative humidity less than

> 40%. The specification of a physical process by the phrase "due_to_" process

> means that the quantity named is a single term in a sum of terms which together

> compose the general quantity named by omitting the phrase. "surface" means

> the lower boundary of the atmosphere. "at_stp" refers to a volume at standard

> conditions of temperature (273.15 K) and pressure (1013.25 hPa). "pm10" refers

> to the fraction of aerosol particles with an aer  odynamic diameter of less than

> or equal to 10 micrometers, where the size cut is applied under ambient

> conditions before the aerosol is dried. A coordinate variable of

> radiation_wavelength or radiation_frequency needs to be specified to indicate

> that the property applies at specific wavelengths or frequencies.

>

>

> 6)

> surface_volume_absorption_coefficient_at_stp_in_air_due_to_pm1_dry_aeros

> ol

>

> The volume absorption coefficient is the fractional change of radiative flux per

> unit path length due to absorption of an incident light beam by a component in

> the reference volume. "Aerosol" means the suspended liquid or solid particles in

> air (except cloud droplets). Aerosol takes up ambient water (a process known as

> hygroscopic growth) depending on the relative humidity and the composition of

> the aerosol. "Dry aerosol" means aerosol fully dehydrated from its ambient

> state, which in practice often means brought to a relative humidity less than

> 40%. The specification of a physical process by the phrase "due_to_" process

> means that the quantity named is a single term in a sum of terms which together

> compose the general quantity named by omitting the phrase. "surface" means

> the lower boundary of the atmosphere. "at_stp" refers to a volume at standard

> conditions of temperature (273.15 K) and pressure (1013.25 hPa). "pm1" refers

> to the fraction of aerosol particles with an aerod  ynamic diameter of less than

> or equal to 1 micrometers, where the size cut is applied under ambient

> conditions before the aerosol is dried. A coordinate variable of

> radiation_wavelength or radiation_frequency needs to be specified to indicate

> that the property applies at specific wavelengths or frequencies.

>

>

> 7)

> surface_volume_absorption_coefficient_at_stp_in_air_due_to_pm10_dry_aero

> sol

>

> The volume absorption coefficient is the fractional change of radiative flux per

> unit path length due to absorption of an incident light beam by a component in

> the reference volume. "Aerosol" means the suspended liquid or solid particles in

> air (except cloud droplets). Aerosol takes up ambient water (a process known as

> hygroscopic growth) depending on the relative humidity and the composition of

> the aerosol. "Dry aerosol" means aerosol fully dehydrated from its ambient

> state, which in practice often means brought to a relative humidity less than

> 40%. The specification of a physical process by the phrase "due_to_" process

> means that the quantity named is a single term in a sum of terms which together

> compose the general quantity named by omitting the phrase. "surface" means

> the lower boundary of the atmosphere. "at_stp" refers to a volume at standard

> conditions of temperature (273.15 K) and pressure (1013.25 hPa). "pm10" refers

> to the fraction of aerosol particles with an aero  dynamic diameter of less than

> or equal to 10 micrometers, where the size cut is applied under ambient

> conditions before the aerosol is dried. A coordinate variable of

> radiation_wavelength or radiation_frequency needs to be specified to indicate

> that the property applies at specific wavelengths or frequencies.

>

>

> 8)

> surface_volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_p

> m1_dry_aerosol

>

> The volume spherical backscattering coefficient is the fractional change of

> radiative flux per unit path length due to redirection of an incident light beam

> into the rearward hemisphere relative to the incident beam by a component in

> the reference volume. It is distinct from the backscattering coefficient which

> isn't integrated over the rearward hemisphere. "Aerosol" means the suspended

> liquid or solid particles in air (except cloud droplets). Aerosol takes up ambient

> water (a process known as hygroscopic growth) depending on the relative

> humidity and the composition of the aerosol. "Dry aerosol" means aerosol fully

> dehydrated from its ambient state, which in practice often means brought to a

> relative humidity less than 40%. The specification of a physical process by the

> phrase "due_to_" process means that the quantity named is a single term in a

> sum of terms which together compose the general quantity named by omitting

> the phrase. "surface" means the lower boundary of the at  mosphere. "at_stp"

> refers to a volume at standard conditions of temperature (273.15 K) and

> pressure (1013.25 hPa). "pm1" refers to the fraction of aerosol particles with an

> aerodynamic diameter of less than or equal to 1 micrometers, where the size cut

> is applied under ambient conditions before the aerosol is dried. A coordinate

> variable of radiation_wavelength or radiation_frequency needs to be specified

> to indicate that the property applies at specific wavelengths or frequencies.

>

>

> 9)

> surface_volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_p

> m10_dry_aerosol

>

> The volume spherical backscattering coefficient is the fractional change of

> radiative flux per unit path length due to redirection of an incident light beam

> into the rearward hemisphere relative to the incident beam by a component in

> the reference volume. It is distinct from the backscattering coefficient which

> isn't integrated over the rearward hemisphere. "Aerosol" means the suspended

> liquid or solid particles in air (except cloud droplets). Aerosol takes up ambient

> water (a process known as hygroscopic growth) depending on the relative

> humidity and the composition of the aerosol. "Dry aerosol" means aerosol fully

> dehydrated from its ambient state, which in practice often means brought to a

> relative humidity less than 40%. The specification of a physical process by the

> phrase "due_to_" process means that the quantity named is a single term in a

> sum of terms which together compose the general quantity named by omitting

> the phrase. "surface" means the lower boundary of the at  mosphere. "at_stp"

> refers to a volume at standard conditions of temperature (273.15 K) and

> pressure (1013.25 hPa). "pm10" refers to the fraction of aerosol particles with

> an aerodynamic diameter of less than or equal to 10 micrometers, where the

> size cut is applied under ambient conditions before the aerosol is dried. A

> coordinate variable of radiation_wavelength or radiation_frequency needs to be

> specified to indicate that the property applies at specific wavelengths or

> frequencies.

>

>

> 10) volume_scattering_coefficient_in_air_due_to_dried_aerosol

>

> The volume scattering coefficient is the fractional change of radiative flux per

> unit path length due to redirection of an incident light beam by a component in

> the reference 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". The specification of a physical process by the phrase

> "due_to_" process means that the quantity named is a single term in a sum of

> terms which together compose the general quantity named by omitting the

> phrase. A coordinate variable of radiation_wavelength or radiation_frequency

> needs to be specified to indicate that the property applies at specific

> wavelengths or frequencies.

>

>

> 11) volume_absorption_coefficient_in_air_due_to_dried_aerosol

>

> The volume absorption coefficient is the fractional change of radiative flux per

> unit path length due to absorption of an incident light beam by a component in

> the reference 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". The specification of a physical process by the phrase

> "due_to_" process means that the quantity named is a single term in a sum of

> terms which together compose the general quantity named by omitting the

> phrase. A coordinate variable of radiation_wavelength or radiation_frequency

> needs to be specified to indicate that the property applies at specific

> wavelengths or frequencies.

>

>

> 12) volume_spherical_backscattering_coefficient_in_air_due_to_dried_aerosol

>

> The volume spherical backscattering coefficient is the fractional change of

> radiative flux per unit path length due to redirection of an incident light beam

> into the rearward hemisphere relative to the incident beam by a component in

> the reference volume. It is distinct from the backscattering coefficient which

> isn't integrated over the rearward hemisphere. "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". The specification of a physical process by the phrase

> "due_to_" process means that the quantity named is a single term in a sum of

> terms which together compose the general quantity named by omitting the

> phrase. A coordinate variable of radiation_wavelength or radiation_frequency

> needs to be specified to indicate that the property  applies at specific

> wavelengths or frequencies.

>

>

> 13)

> surface_volume_scattering_coefficient_at_stp_in_air_due_to_pm1_dried_aero

> sol

>

> The volume scattering coefficient is the fractional change of radiative flux per

> unit path length due to redirection of an incident light beam by a component in

> the reference 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". The specification of a physical process by the phrase

> "due_to_" process means that the quantity named is a single term in a sum of

> terms which together compose the general quantity named by omitting the

> phrase. "surface" means the lower boundary of the atmosphere. "at_stp" refers

> to a volume at standard conditions of temperature (273.15 K) and pressure

> (1013.25 hPa). "pm1" refers to the fraction of aerosol particles w  ith an

> aerodynamic diameter of less than or equal to 1 micrometer, where the size cut

> is applied under ambient conditions before aerosol humidity, pressure, or

> temperature are possibly altered. A coordinate variable of radiation_wavelength

> or radiation_frequency needs to be specified to indicate that the property

> applies at specific wavelengths or frequencies.

>

>

> 14)

> surface_volume_scattering_coefficient_at_stp_in_air_due_to_pm10_dried_aer

> osol

>

> The volume scattering coefficient is the fractional change of radiative flux per

> unit path length due to redirection of an incident light beam by a component in

> the reference 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". The specification of a physical process by the phrase

> "due_to_" process means that the quantity named is a single term in a sum of

> terms which together compose the general quantity named by omitting the

> phrase. "surface" means the lower boundary of the atmosphere. "at_stp" refers

> to a volume at standard conditions of temperature (273.15 K) and pressure

> (1013.25 hPa). "pm10" refers to the fraction of aerosol particles  with an

> aerodynamic diameter of less than or equal to 10 micrometers, where the size

> cut is applied under ambient conditions before aerosol humidity, pressure, or

> temperature are possibly altered. A coordinate variable of radiation_wavelength

> or radiation_frequency needs to be specified to indicate that the property

> applies at specific wavelengths or frequencies.

>

>

> 15)

> surface_volume_absorption_coefficient_at_stp_in_air_due_to_pm1_dried_aer

> osol

>

> The volume absorption coefficient is the fractional change of radiative flux per

> unit path length due to absorption of an incident light beam by a component in

> the reference 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". The specification of a physical process by the phrase

> "due_to_" process means that the quantity named is a single term in a sum of

> terms which together compose the general quantity named by omitting the

> phrase. "surface" means the lower boundary of the atmosphere. "at_stp" refers

> to a volume at standard conditions of temperature (273.15 K) and pressure

> (1013.25 hPa). "pm1" refers to the fraction of aerosol particles wi

>  th an aerodynamic diameter of less than or equal to 1 micrometers, where the

> size cut is applied under ambient conditions before aerosol humidity, pressure,

> or temperature are possibly altered. A coordinate variable of

> radiation_wavelength or radiation_frequency needs to be specified to indicate

> that the property applies at specific wavelengths or frequencies.

>

>

> 16)

> surface_volume_absorption_coefficient_at_stp_in_air_due_to_pm10_dried_aer

> osol

>

> The volume absorption coefficient is the fractional change of radiative flux per

> unit path length due to absorption of an incident light beam by a component in

> the reference 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". The specification of a physical process by the phrase

> "due_to_" process means that the quantity named is a single term in a sum of

> terms which together compose the general quantity named by omitting the

> phrase. "surface" means the lower boundary of the atmosphere. "at_stp" refers

> to a volume at standard conditions of temperature (273.15 K) and pressure

> (1013.25 hPa). "pm10" refers to the fraction of aerosol particles w

>  ith an aerodynamic diameter of less than or equal to 10 micrometers, where the

> size cut is applied under ambient conditions before aerosol humidity, pressure,

> or temperature are possibly altered. A coordinate variable of

> radiation_wavelength or radiation_frequency needs to be specified to indicate

> that the property applies at specific wavelengths or frequencies.

>

>

> 17)

> surface_volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_p

> m1_dried_aerosol

>

> The volume spherical backscattering coefficient is the fractional change of

> radiative flux per unit path length due to redirection of an incident light beam

> into the rearward hemisphere relative to the incident beam by a component in

> the reference volume. It is distinct from the backscattering coefficient which

> isn't integrated over the rearward hemisphere. "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". The specification of a physical process by the

> phrase "due_to_" process means that the quantity named is a single term in a

> sum of terms which together compose the general quantity named by omitting

> the phrase. "surface" means the lower boundar

>  y of the atmosphere. "at_stp" refers to a volume at standard conditions of

> temperature (273.15 K) and pressure (1013.25 hPa). "pm1" refers to the fraction

> of aerosol particles with an aerodynamic diameter of less than or equal to 1

> micrometers, where the size cut is applied under ambient conditions before

> aerosol humidity, pressure, or temperature are possibly altered. A coordinate

> variable of radiation_wavelength or radiation_frequency needs to be specified

> to indicate that the property applies at specific wavelengths or frequencies.

>

>

> 18)

> surface_volume_spherical_backscattering_coefficient_at_stp_in_air_due_to_p

> m10_dried_aerosol

>

> The volume spherical backscattering coefficient is the fractional change of

> radiative flux per unit path length due to redirection of an incident light beam

> into the rearward hemisphere relative to the incident beam by a component in

> the reference volume. It is distinct from the backscattering coefficient which

> isn't integrated over the rearward hemisphere. "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". The specification of a physical process by the

> phrase "due_to_" process means that the quantity named is a single term in a

> sum of terms which together compose the general quantity named by omitting

> the phrase. "surface" means the lower boundar

>  y of the atmosphere. "at_stp" refers to a volume at standard conditions of

> temperature (273.15 K) and pressure (1013.25 hPa). "pm10" refers to the

> fraction of aerosol particles with an aerodynamic diameter of less than or equal

> to 10 micrometers, where the size cut is applied under ambient conditions

> before aerosol humidity, pressure, or temperature are possibly altered. A

> coordinate variable of radiation_wavelength or radiation_frequency needs to be

> specified to indicate that the property applies at specific wavelengths or

> frequencies.

>

> _______________________________________

> Dr. Markus Fiebig

>

> 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: Markus.Fiebig at nilu.no<mailto:Markus.Fiebig at nilu.no>

> skype: markus.fiebig

>

> _______________________________________________

> CF-metadata mailing list

> CF-metadata at cgd.ucar.edu<mailto:CF-metadata at cgd.ucar.edu>

> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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