Jonathan W-- Whoops, two Jonathans in the thread -- I should have included a last name. Sorry for the confusion!
My reply was to Jonathan Gregory's question about indicating the start/end pressures. If the total totals and showalter indices are always calculated for the same pressure heights, I agree, it makes sense to include those in the definition and leave off any mention of starting/ending coordinate variables. (But now we've got a backup option in case someone comes up with a generalized version that isn't always 500/850 mb...) Cheers, --Seth On Wed, 29 May 2013 14:31:03 -0400 Jonathan Wrotny <[email protected]> wrote: >Dear Seth, > >Yes, I remember your new standard names. In fact, I just updated the >definition of the lifted index to include these two names. However, the total >totals index (and others, such as the showalter index) are somewhat different >beasts than the lifted index in that they really do not have 'non-standard >heights' for calculating the index. As far as I know (and someone please >correct me if I am wrong), the pressure height levels for the total totals >index are specifically fixed to 850 and 500 hPa. I am not aware of the total >totals index being calculated at any other pressure levels, so I chose not to >include the air_pressure_of_X standard names as coordinate variables in the >definition since I figured there was no obvious reason to generalize these >definitions. I also left them out of the showalter index definition, as well. > These stability indices are in effect unique, one-off, quantities that don't >really need further generalization, at least as I see it. > >Related to this point, some might argue that the lifted index standard name is >also fixed to the surface and 500 hPa pressure levels. While this is >generally the case, I believe, I have found some instances where the 500 hPa >level is not used when calculating the index. So, I think of the lifted index >as more of a general index for adiabatic lifting of a parcel between two >arbitrary pressure levels, and thus should include your two proposed >air_pressure_of_X standard names. > >Sincerely, > >Jonathan > >On 5/29/2013 2:11 PM, Seth McGinnis wrote: >> 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 <[email protected]> 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 <[email protected]> ----- >>> >>>> Date: Wed, 29 May 2013 12:00:42 -0400 >>>> From: Jonathan Wrotny <[email protected]> >>>> User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130509 >>>> Thunderbird/17.0.6 >>>> To: Jonathan Gregory <[email protected]>, John Graybeal >>>> <[email protected]>, [email protected] >>>> 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 >>>>>> _______________________________________________ >>>>>> CF-metadata mailing list >>>>>> [email protected] >>>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >>>>> >>>>> >>>>> _______________________________________________ >>>>> CF-metadata mailing list >>>>> [email protected] >>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >>> ----- End forwarded message ----- >>> _______________________________________________ >>> CF-metadata mailing list >>> [email protected] >>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata >> _______________________________________________ >> CF-metadata mailing list >> [email protected] >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
