[CF-metadata] Proposal for new standard names

From: Cameron-smith, Philip <cameronsmith1>
Date: Fri, 25 Feb 2011 18:28:05 -0800

> -----Original Message-----
> From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-
> bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
> Sent: Friday, February 25, 2011 5:25 AM
> To: Tomoo Ogura
> Cc: Jennifer Kay; Yoko Tsushima; cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] Proposal for new standard names
>
> Dear Tomoo
>
> > I agree that the word "sedimentation" needs more clarification.
> >
> > >(1')
> tendency_of_mass_fraction_of_stratiform_cloud_liquid_water_in_air_
> > > due_to_sedimentation_of_cloud_liquid_water .
> >
> > In this proposal, I hope to supplement the standard names which
> describe
> > the cloud budget of various GCMs, and the above option (1') is
> exactly
> > what we need for this purpose (i.e., it fits the variable name in a
> GCM).
>
> It looks repetitive, but it appears that this clarification is
> necessary
> since you also have
>
> (2)
> tendency_of_mass_fraction_of_stratiform_cloud_condensed_water_in_air_
> _due_to_sedimentation_of_cloud_liquid_water
>
> Can "sedimentation" in this context only refer to cloud liquid water,
> or
> could the same word be applied to cloud ice as well? (Please excuse my
> ignorance - I am not a cloud microphysicist!)
>
> Best wishes
>
> Jonathan

Hi Jonathan,

I think one could apply 'sedimentation' to each of aerosols, liquid_water, and ice.

That said, I would usually use 'precipitation' instead of 'sedimentation' for liquid_water and ice, and 'sedimentation' for aerosols.

I'm not sure if there is a formal distinction between 'precipitation' and 'sedimentation' for the atmosphere. The only distinction I can think of is that 'precipitation' makes me think of *fast* fall speeds and 'sedimentation' makes me think of *slow* fall speeds.

I do note that 'sedimentation' is currently only used in CF for ocean names (eg, tendency_of_ocean_mole_content_of_carbon_due_to_sedimentation), whereas 'precipitation' is already used for atmospheric terms (eg, tendency_of_specific_humidity_due_to_stratiform_precipitation).

This suggests to me CF should use 'precipitation' in the proposal above, unless one wants to make some distinction on the basis of fall speed. However, 'precipitation' will sound odd if/when extended to aerosols, so I suggest that there be some mention in the description/help text to help with discovery (ie whether precipitation includes sedimentation, or not).

Best wishes,

      Philip

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Dr Philip Cameron-Smith, pjc at llnl.gov, Lawrence Livermore National Lab.
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Received on Fri Feb 25 2011 - 19:28:05 GMT