Hi Philip,
I agree with your proposals.
I think it's a good idea to adopt an existing phrase for std_names
that fits our needs - thanks for letting me know this.
Best wishes,
Tomoo
----- Original Message -----
From: "Cameron-smith, Philip" <[email protected]>
To: "Tomoo Ogura" <[email protected]>; "Bert Jagers" <[email protected]>; "Jonathan Gregory"
<[email protected]>
Cc: "Jennifer Kay" <[email protected]>; "Yoko Tsushima" <[email protected]>;
<[email protected]>
Sent: Friday, March 11, 2011 11:15 AM
Subject: RE: [CF-metadata] Proposal for new standard names - use
of"sedimentation"
Thanks, Bert.
I am embarrassed to say that I didn't notice/remember/discover that CF already has the term/phrase
we need until your email. It is:
gravitational_settling
This is used in 6 std_names, and has the meaning that we want, although the distinction/overlap with
precipitation was never discussed, presumably because these std_names were connected to movement of
aerosols.
An example of one of the existing std_names is:
tendency_of_atmosphere_mass_content_of_black_carbon_dry_aerosol_due_to_gravitational_settling
Hence, I propose that we replace 'sedimentation' with 'gravitational settling' in your std_names for
cloud drops.
I further propose that we still add text to the descriptions that clearly distinguishes
'gravitational_settling' from 'precipitation' along the lines you previously proposed.
As a footnote for the grammar discussion in another thread: I would have been more likely to
discover the 'gravitational_settling' term if CF was using a grammar-vocabulary system.
Best wishes,
Philip
-----------------------------------------------------------------------
Dr Philip Cameron-Smith, [email protected], Lawrence Livermore National Lab.
-----------------------------------------------------------------------
-----Original Message-----
From: [email protected] [mailto:cf-metadata-
[email protected]] On Behalf Of Tomoo Ogura
Sent: Wednesday, March 09, 2011 1:57 AM
To: Bert Jagers; Cameron-smith, Philip; Jonathan Gregory
Cc: Jennifer Kay; Yoko Tsushima; [email protected]
Subject: Re: [CF-metadata] Proposal for new standard names - use of
"sedimentation"
Dear Bert,
Many thanks for your comments and suggestions.
In the proposed new standard names, the word "sedimentation"
was meant to represent the gravitational settling of cloud
liquid water droplets.
I agree that the above usage of "sedimentation" does not
match a transition from one medium to another. Therefore,
we may need to look for another word to avoid confusion.
As an alternative, the suggested word "settling" sounds
good to me. In this case, the proposed standard names
will be as follows;
(a) tendency_of_mass_fraction_of_stratiform_cloud_liquid_water
_in_air_due_to_settling_of_cloud_liquid_water,
and
(b) tendency_of_mass_fraction_of_stratiform_cloud_condensed_water
_in_air_due_to_settling_of_cloud_liquid_water.
Best wishes,
Tomoo
----- Original Message -----
From: "Bert Jagers" <[email protected]>
To: "Tomoo Ogura" <[email protected]>; "Cameron-smith, Philip"
<[email protected]>; "Jonathan
Gregory" <[email protected]>
Cc: "Jennifer Kay" <[email protected]>; "Yoko Tsushima"
<[email protected]>;
<[email protected]>
Sent: Wednesday, March 09, 2011 9:22 AM
Subject: Re: [CF-metadata] Proposal for new standard names - use of
"sedimentation"
> Dear all,
>
> Unfortunately I have had far too little time to contribute to the CF
mailing list over the past
> year, but I try to scan the titles of mails coming in and now and
then I read a post. I didn't
> intend to read this thread until my eye accidentally caught the word
"sedimentation" in body text.
> As someone involved in sediment transport in rivers, estuaries,
coastal areas and to a much lesser
> oceans, I do have a strong association with the word "sedimentation".
As a result I have some
> concerns with the appropriateness of the chosen word.
>
> If I interpret the most recent discussion correctly, the proposal is
to use the word
> "sedimentation" for the slow downward motion of liquid water in the
atmosphere; not being an
> atmospheric scientist I'm trying to grasp what that actually means.
The discussion distinguishes
> it from definitions including terms like "accretion" and
"autoconversion" which based on the
> description in the standard name table both seem to be related the
growth of droplets and ice
> crystals; flocculation is the associated process in cohesive sediment
modeling. Other processes
> that thus would be included in your new definition of "sedimentation"
include: vertical advection
> due to general air velocity, turbulent mixing, relative gravitational
settling of the
> droplets/crystals, ... more?
>
> In sediment transport, the words "sedimentation" and "deposition" are
generally used to mean the
> reverse of "erosion". The former two mean that sediment falls from
suspension onto the bed ("ocean
> floor"), whereas "erosion" means the uptake of sediment from the bed
by the flow. Now, let us see
> how the word "sedimentation" was used before in CF names. The term
"sedimentation" has so far been
> used in three standard names related to the ocean_mole_content of
three chemical substances. These
> names are associated with 2D quantities (quantities per unit area)
which matches my interpretation
> of the word (and the common use of this word): the amount of the
substances considered (carbon,
> elemental nitrogen, and iron) in the ocean column is reduced due to
the fact that organic
> suspended sediment settles onto the ocean floor. Basically it
includes a transition from one
> medium (in the water column) to another medium (in/on the ocean
floor). The newly proposed use of
> the term "sedimentation" does not match such a transition.
>
> Thinking along these lines I looked at the word "deposition" which is
used more frequently in
> standard names. However, mostly it is used in combination with "dry",
"wet" or "turbulent" and
> seem to be associated with the transition of substances from medium
atmosphere to the medium ocean
> (or land): a 2D flux field of 2D variable "atmosphere mass content"
in line with the use of the
> word "sedimentation" described above. The word "deposition" without
"dry" or "wet" is less
> uniquely tied to a specific process. It has been used as the reverse
of "sublimation" in
>
tendency_of_mass_fraction_of_stratiform_cloud_ice_in_air_due_to_deposit
ion_and_sublimation, as the
> sum of "dry deposition" and "wet deposition" (= "turbulent
deposition" + "gravitational
> settling"), and in a non-specified manner in
>
tendency_of_ocean_mole_content_of_iron_due_to_deposition_and_runoff_and
_sediment_dissolution.
>
> In ocean modeling I would tend to use the word "settling" for the
downward motion of sediment
> relative to the water without necessarily hitting the ocean floor,
but also the word "settling"
> has so far only been used in combination with 2D variables of type
"atmosphere mass content" and
> deposition.
>
> Best regards,
>
> Bert
> ------
>
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