[CF-metadata] standard names for aerosols and chemistry

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 21 Sep 2006 21:12:53 +0100

Dear Christiane et al.

Regarding Roy's comment, it would be fair to say that these names do already
result from consultation among some experts on atmos chemistry within your
group, wouldn't it? I think what is mostly needed here is comments on how
chemical names of this kind fit with CF standard names in general. Roy's
comment shows that they may need to be more self-explanatory. It is generally
the case that we have to make standard names more explicit than domain experts
would expect, so that people from other disciplines can understand them
easily. That kind of issue has occurred before, with meteorologists assuming
that oceanographers will understand them and vice-versa, etc.

Sorry for my slow response. I have a few comments.

On names of species:

* The construction X_as_Y seems fine to me, to indicate that you mean X when it
comes as a constituent of Y. But it some cases I wonder if it is really
necessary. What is meant by ammonium_as_ammonium?

* You have organic_carbon_as_particulate_organic_carbon_dry_aerosol and
organic_carbon_as_particulate_organic_carbon_dry_aerosol. In these cases, could
you not omit the first "organic"? - since carbon is carbon, and whether it is
organic depends on what it is a constituent of.

* How can you have a wet deposition flux of a dry aerosol? What does "dry
aerosol" mean, I wonder.

* Like Roy, I don't know what mercury_0 and mercury_2 mean.

* I don't understand aerosol_water_ambient_aerosol.

* I can understand non_methane_volatile_organic_compounds but I don't know what
they are. Are they a well-known group so that this is obvious to an expert?
Later they appear as NMVOC. I think we should have one or the other, and
putting it in full seems more consistent with your other names.

* CO should appear as carbon_monoxide.

Use of dimensions:

* Some of the names have numerical values in them. This is not in keeping with
usual practice in standard names. For instance, we do not have standard names
for surface air temperature at 1.5 m or 2 m height. Instead, we use coordinates
for independent variables. In names like these:
  mole_fraction_of_CO_with_lifetime_of_25_days_in_air
  pm10_aerosol_ambient_optical_depth_at_550_nm
  mass_fraction_of_pm10_aerosol_at_50_percent_relative_humidity_in_air
I think the lifetime, particle radius, wavelength and relative humidity should
be coordinates (probably scalar coordinate variables), rather than being in the
standard name. This requires standard names to be defined for the independent
variables you need.

* In a similar way, you have phrases from_North_America, from_South_Asia and so
on. I know this is similar to the construction from_stratosphere which we
discussed in your guidelines, but I don't think we ought to include geo-
graphical areas in standard names. We have already defined a standard_name of
region for use as a geographical "coordinate". Your use is not quite the same
because you want to identify where something comes from, rather than its
present location, so perhaps we should introduce a new name of source_region
for instance, with the same possible values as region; these come from a list
which can be extended as required.

Other points:

* grid_cell_area and _height. These are metrics for the grid, rather than
quantities which need standard names. Grid cell area should be specified by a
cell_measures variable of area (CF 7.2). Grid cell height can be deduced as the
difference between the lower and upper boundary in the vertical coordinate. If
it has to be stored separately we could add a cell_measures for it.

* atmosphere_mass_content_of_air. I think we agreed this would be named in the
more obvious way atmosphere_mass_per_unit_area, since it seems strange to
give something a "content" name for its entire content!

* "of" is missing in surface_emission_mass_flux_ammonia.

Best wishes

Jonathan
Received on Thu Sep 21 2006 - 14:12:53 BST