Hi Jonathan,
I suggested two such standard_names in an email on Friday,
because I need them for various CAPE/CIN/etc standard_names:
air_pressure_of_lifted_parcel_at_start
air_pressure_of_lifted_parcel_at_finish
These would have the following definitions:
Various stability and convective potential indices are calculated by
"lifting" a parcel of air: moving it dry adiabatically from a starting
height (often the surface) to the Lifting Condensation Level, and then
wet adiabatically from there to an ending height (often the top of
the data/model/atmosphere). air_pressure_of_lifted_parcel_at_start
[finish] is the pressure height at the beginning [end] of lifting.
Both would have canonical units of Pa
We could then add the following final sentence to the definition for the
total totals index: "If the index is calculated between non-standard
heights, they should be specified using auxiliary coordinate variables of
air_pressure_of_lifted_parcel_at_start and
air_pressure_of_lifted_parcel_at_finish."
Does that seem like it would work?
Cheers,
--Seth
On Wed, 29 May 2013 18:17:49 +0100
Jonathan Gregory <j.m.gregory at reading.ac.uk> wrote:
>Dear Jonathan
>
>It would be all right to specify coordinate variables (size one or scalar)
>for the two levels, but they would have to be distinguishable. That means
>they'd have to have different standard names, I suppose - what would they be?
>It seems to me this would then tend towards the generalisation of this
>quantity, for which you didn't see an immediate need when you proposed it.
>It would be simpler to remain hard-wired, if that's the use-case.
>
>Best wishes
>
>Jonathan
>
>----- Forwarded message from Jonathan Wrotny <jwrotny at aer.com> -----
>
>> Date: Wed, 29 May 2013 12:00:42 -0400
>> From: Jonathan Wrotny <jwrotny at aer.com>
>> User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130509
>> Thunderbird/17.0.6
>> To: Jonathan Gregory <j.m.gregory at reading.ac.uk>, John Graybeal
>> <graybeal at marinemetadata.org>, cf-metadata at cgd.ucar.edu
>> Subject: Re: [CF-metadata] new standard name: total_totals_index
>>
>> Jonathan,
>>
>> I wanted to make a minor addition to the definition of the total
>> totals index to include coordinate variables for the 850 and 500 hPa
>> pressure levels. It seems that this information might be useful to
>> have in a netCDF file, but not be specifically required. Please let
>> me know if you think this sentence is unnecessary and I can remove.
>>
>> Standard Name:
>>
>> atmosphere_stability_total_totals_index
>>
>> Definition:
>>
>> The atmosphere_stability_total_totals_index indicates the
>> likelihood of severe convection and is often referred to as simply the
>> total totals index. The index is derived from the difference in air
>> temperature between 850 and 500 hPa (the vertical totals) and the
>> difference between the dew point temperature at 850 hPa and the air
>> temperature at 500 hPa (the cross totals). The vertical totals and cross
>> totals are summed to obtain the index.Coordinate variables can be specified
>which
>> indicate the 850 and 500 hPa pressure levels.
>>
>> Canonical Units: K
>>
>> Does this standard name/definition/units seems suitable to the CF board?
>>
>> FYI, I will be submitting two other stability indices this week. Sincerely,
>>
>> Jonathan
>>
>> On 5/22/2013 1:42 PM, Jonathan Wrotny wrote:
>> >Dear Jonathan,
>> >
>> >Thanks for your feedback. I agree with your suggested
>> >modifications the definition and have included them below.
>> >
>> >Also, there is an e-mail from John Graybeal who is suggesting a
>> >more generalized version of the standard name. I have thought
>> >about attempting to come up with a similar, general, name for the
>> >total totals index. But, this name was so long that I believe
>> >that it would itself become a full description, which I was trying
>> >to avoid. John's suggested name boils it down more generally and
>> >succintly, but it turns out that this name could also be
>> >applicable to the stability index, "k index," which I am going to
>> >submit in the coming days (which also uses differences of the
>> >ambient and dew point temperatures), so there would be conflict
>> >with the "k index" name. Also, remember that the total totals is
>> >not a name that I have personally constructed to describe the
>> >mathematics of the quantity, but it is actually the name of an
>> >commonly used meteorological quantity.
>> >
>> >Given Jonathan's previous direction (see e-mails concerning
>> >"lifted index") to attempt to standardize all names except for
>> >those specific, complex quantities that don't lend themselves to
>> >generalization, I think keeping total_totals_index in the standard
>> >name is a good idea. I think the lifted index is complex and
>> >specific enough that it falls into the category or meriting a
>> >unique name (similar to, say, the NDVI).
>> >
>> >Standard Name:
>> >atmosphere_stability_total_totals_index
>> >Definition:
>> >The atmosphere_stability_total_totals_index indicates the
>> >likelihood of severe convection and is often referred to as simply the
>> >total totals index. The index is derived from the difference in air
>> >temperature between 850 and 500 hPa (the vertical totals) and the
>> >difference between the dew point temperature at 850 hPa and the air
>> >temperature at 500 hPa (the cross totals). The vertical totals and cross
>> >totals are summed to obtain the index.
>> >Canonical Units: K
>> >
>> >Sincerely,
>> >
>> >Jonathan
>> >
>> >On 5/21/2013 5:39 PM, Jonathan Gregory wrote:
>> >>Dear Jon
>> >>
>> >>>I agree with your assessment, and I like your proposed name. My
>> >>>only question remains with the definition. It seems like there
>> >>>could be two approaches given the specific nature of the product: 1)
>> >>>write the definition as below with hard-wired pressure levels part
>> >>>of the definition. Based on my understanding of the product, I have
>> >>>never seen any other pressures levels other than 500 and 850 hPa
>> >>>used for the index, but I could be wrong. -or- 2) attempt to
>> >>>generalize the definition so that it does not mention the specific
>> >>>pressure levels. This would help to generalize the definition, but
>> >>>may not add that much value since other pressure levels do not
>> >>>appear to be commonly used (ever?).
>> >>If that is the case, then (1) seems the better choice
>> >>
>> >>>Standard Name: atmosphere_stability_total_totals_index
>> >>>
>> >>>Definition:
>> >>>
>> >>>Option 1)The atmosphere_stability_total_totals_index indicates the
>> >>>likelihood of severe convection and is often referred to as simply
>> >>>the total totals index. The index is derived from the difference in
>> >>>air temperature between 850 and 500 hPa (the vertical totals) and
>> >>>the difference between the dew point temperature at 850 hPa and the
>> >>>air temperature at 500 hPa (the cross totals). The vertical totals
>> >>>and cross totals are summed to obtain the index.
>> >>You could insert
>> >>>often referred to as simply the total totals index
>> >>as in your other definition. This bit:
>> >>>Air temperature is
>> >>>the bulk temperature of the air, not the surface (skin) temperature.
>> >>>The term "surface" means the lower boundary of the atmosphere.
>> >>doesn't seem necessary in this case, since "surface" is not mentioned.
>> >>
>> >>>Canonical Units: K
>> >>Oh, good. :-)
>> >>
>> >>If we define it specifically now, that does not preclude the later
>addition of
>> >>a more general standard name if required.
>> >>
>> >>Cheers
>> >>
>> >>Jonathan
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>> >
>> >
>> >
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>
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Received on Wed May 29 2013 - 12:11:22 BST
