[CF-metadata] new standard name: lifted_index

From: Jonathan Gregory <j.m.gregory>
Date: Sat, 18 May 2013 15:05:45 +0100

Dear Jonathan

> lifted_index
>
> with the associated definition:
>
> The Lifted Index (LI) is an index that provides a measure of the
> instability of the atmosphere. The index is defined as the
> temperature difference between a parcel of air lifted from the
> surface to a given air pressure in the troposphere and the ambient
> air temperature at a given air pressure in the troposphere.

I think this presents an example of a kind of problem we have had before with
the standard name table (and total_totals_index does too - in my next email),
that there's a conflict between (a) using a term that is in common use in its
field of application, but which is opaque jargon to anyone who is not familiar
with it, or (b) using something more descriptive, which would be understandable
to more people, but surprising to those who are familiar with the jargon term,
who might not recognise the quantity for what it is. The reason why we have
this conflict is that the standard name table, and CF-netCDF datasets, cover
many geophysical disciplines. Also I think the term "standard name" has often
been a cause of disappointed expectations, because actually many of them are
not names, but short definitions.

>From a generalistic perspective I tend to argue for (b) and domain experts
often argue for (a), not surprisingly! In this case, I would like to make a
(b)-type proposal. We could call this quantity

temperature_difference_between_ambient_air_and_surface_air_lifted_adiabatically

Would people who know "lifted index" recognise that as being the definition of
this quantity? Have I written that the right way round i.e. is it ambient air
temperature minus lifted surface air temperature? If we did adopt such a name,
then its definition would say that this is often called the "lifted index". But
it is also a general-purpose atmopheric quantity.

Cheers

Jonathan
Received on Sat May 18 2013 - 08:05:45 BST