[CF-metadata] volume integral

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 30 Jul 2014 15:04:54 +0100

Dear Mark

> We have a requirement to calculate volume integrals for a large range of model diagnostics. We would like a method to correctly identify these derived fields.
>
> I am interested in creating a new cell_method, an integral, which would allow us to use this approach with any standard name.
>
> Such a cell method will necessarily alter the units of the quantity by a factor dependent on the dimensions integrated over.
>
> For example, I would like to store a data variable:
>
> double deltaSeaIron(time, depth, lat, lon)
> deltaSeaIron:standard_name = "tendency_of_mole_concentration_of_iron_in_sea_water_due_to_biological_production" ;
> deltaSeaIron:units = "mol s-1" ;
> deltaSeaIron:cell_methods = "depth: lat: lon: integral" ;

I can appreciate why you propose that but I would say that it is not consistent
with the intention of cell_methods or the practice in the standard_name table.
cell_methods is for describing variation within cells. Doing an integral is
a change of variable. It converts an intensive quantity into an extensive
quantity. There are very many other examples of this - hundreds, I expect. For
example, rainfall_amount is a time-integral of rainfall_rate, and they are
described by different standard_names, not distinguished by cell_methods.
atmosphere_mole_content_of_ozone (mol m-2) is the vertical integral in the
atmosphere of mole_concentration_of_ozone_in_air (mol m-3), again distinguished
by standard names. In the case you mention, I think a new standard_name is
needed, something like
tendency_of_ocean_moles_of_iron_due_to_biological_production
A construction like that would be analogous to many existing standard names
(for many different species) of the form tendency_of_atmosphere_moles_of_X.

Best wishes

Jonathan
Received on Wed Jul 30 2014 - 08:04:54 BST