Hello Jonathan,
Thanks for your reply to this post. I see your point of view. I guess
it would be odd if a name "lifted_index" was adopted when the general
naming paradigm for the CF standard names is to attempt to phrase each
quantity in general atmospheric terms so that they are general purpose
across all disciplines. I can see the advantage of each approach you
mention, but it does seem best (if possible) to try to generally define
each name. In terms of the GOES-R atmospheric products, there will be
four atmospheric stability indices (of which I've only posted two so
far). In thinking about them, I believe that two of them could have
general names - like the one you've suggested below - while the other
two are sufficiently complex that a name such as
"atmospheric_stability_total_totals_index" will be necessary.
The "lifted_index" is simple enough so that your proposed name should
work well. In light of your suggestions, these could be the
name/definition/units:
Standard Name:
temperature_difference_between_ambient_air_and_surface_air_lifted_adiabatically
Definition: This quantity is defined as the temperature difference
between a parcel of air lifted adiabatically from the surface to a given
air pressure in the troposphere and the ambient air temperature at a
given air pressure in the troposphere. It is often called the lifted
index (LI) and provides a measure of the instability of the atmosphere.
The air parcel is "lifted" by moving the air parcel from the surface to
the Lifting Condensation Level (dry adiabatically) and then from the
Lifting Condensation Level to a given air pressure (wet adiabatically).
Air temperature is the bulk temperature of the air, not the surface
(skin) temperature. The term "surface" means the lower boundary of the
atmosphere. A coordinate variable of air_pressure can be specified to
indicate the specific air pressure that the temperature difference is
calculated at.
Canonical Units: K
Sincerely,
Jonathan
On 5/18/2013 10:05 AM, Jonathan Gregory wrote:
> 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
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Received on Mon May 20 2013 - 14:30:50 BST
