With that fix, I'm happy with Jonathan's suggestion. Karl On 5/9/19 10:03 AM, Jonathan Gregory wrote: > Actually it should be northward_wind, not northward_velocity. > > ----- Forwarded message from Jonathan Gregory <j.m.greg...@reading.ac.uk----- > > Date: Thu, 9 May 2019 18:02:32 +0100 > > Dear Martin et al. > > Is it sum_x (v'(x) T'(x)) where v'=v-avg_x(v), similarly for T, and x is > longitude? In that case I think it would be neat to describe it as a > covariance, which like "product" doesn't attribute a physical meaning to it. > Could it be called > covariance_over_longitude_of_northward_velocity_and_air_temperature > where the (important) fact that it is calculated on pressure levels can be > adequately indicated by its having a coordinate of pressure, I think. The > same quantity could be computed on other sorts of levels. > > Best wishes > > Jonathan > > ----- Forwarded message from Martin Juckes - UKRI STFC > <martin.juc...@stfc.ac.uk> ----- > >> PS: Michaela sent another suggestion while I was composing that email: >> >> >> covariance_of_northward_velocity_and_temperature .. which could work, though >> I think it would need a prefix of "zonal_isobaric". >> >> regards, >> Martin >> >> >> >> >> ________________________________ >> From: Juckes, Martin (STFC,RAL,RALSP) >> Sent: 08 May 2019 09:55 >> To: CF-metadata (cf-metadata@cgd.ucar.edu) >> Cc: Plummer, David (EC); David Neubauer; sen...@meteo.fr; RIGOUDY Gaelle; >> Michael Schulz; Michaela Hegglin; Taylor, Karl E. >> Subject: Standard name of isobaric zonal mean eddy meridional temperature >> advection >> >> >> Hello All, >> >> >> For AerChemMIP we need a new standard name for a quantity which is the >> isobaric zonal mean of the eddy meridional temperature advection. That is, >> the mean wrt. longitude of the product of v' and T', where v' and T' are the >> eddy meridional velocity and air temperature respectively and "eddy" denotes >> the departure from the isobaric zonal mean. The units should be "K m s-1" >> >> >> This is related to two existing terms: >> >> 1. northward_heat_flux_in_air_due_to_eddy_advection [W m-2] >> 2. product_of_northward_wind_and_air_temperature [K m s-1] >> >> The first of these involves the eddy advection, but includes a factor of >> density and the specific heat constant. Since density is spatially varying, >> (1) can not be directly converted to the term we want, though there is an >> approximate relationship. >> >> The second specifies the product, but without reference to the eddies. >> >> The term "eddy_advection" occurs in 38 existing terms, always in the form >> "...._due_to_[...]eddy_advection", describing the part of some process which >> can be attributed to some kind of eddy advection. In this case we want a >> term for the eddy advection itself. >> >> In some preliminary discussion we have the following ideas: >> >> (1) >> northward_heat_flux_expressed_as_temperature_flux_in_air_due_to_eddy_advection >> -- staying close to the existing heat flux term; >> (2) northward_temperature_flux_in_air_due_to_eddy_advection -- more >> descriptive >> (3) Karl has suggested terms based on "product_of_...", to avoid the use of >> "temperature flux", because the notion of "flux" sits uncomfortably with a >> non-conservative quantity like temperature. >> >> In reviewing the use of "eddy_advection" in existing terms, I can see that >> the nature of the eddy advection is clearly defined in 27 of them, and the >> heat flux term above is the only one for which the user is left to guess. >> The standard interpretation would be as a departure from the isobaric zonal >> mean, but that is not spelled out in the standard name. >> >> Combining some of the ideas from Karl and Michaela (suggestion 2 above), I >> think we could use: >> >> >> * northward_isobaric_zonal_mean_eddy_advection_of_air_temperature >> >> This differs from Karl's suggestions in using "eddy_advection" rather than >> trying to adapt "product_of" to deal with this use case. >> >> The phrase "isobaric_zonal_mean_eddy_advection" would be defined as the >> zonal mean advection by eddies defined as the departure from the >> instantaneous isobaric zonal mean of the velocity and the advected quantity. >> >> I'm submitting this on behalf of the group, so please consider comments by >> Karl and Michaela below. The discussion is still quite open, but I think it >> is better to engage with the CF list at this stage (the definition of the >> term we want to represent is clear). >> >> regards, >> Martin >> ________________________________ >> From: Taylor, Karl E. <taylo...@llnl.gov> >> Sent: 07 May 2019 23:15 >> To: Michaela Hegglin; Juckes, Martin (STFC,RAL,RALSP) >> Cc: Plummer, David (EC); David Neubauer; sen...@meteo.fr; RIGOUDY Gaelle; >> Michael Schulz >> Subject: Re: vt100 >> >> I just noticed that there is a standard_name >> "product_of_northward_wind_and_air_temperature". Perhaps this could be >> modified to something indicating we're only considering the "eddy" >> component, e.g., >> "eddy_component_of_product_of_northward_wind_and_air_temperature" or >> "product_of_northward_wind_and_air_temperature_eddy_components" or >> eddy_associated_product_of_northward_wind_and_air_temperature". >> best, >> Karl >> >> On 5/7/19 2:23 AM, Michaela Hegglin wrote: >>> Hi Martin, Karl, >>> >>> I got some more input from the DynVarMIP people on this too and Martin has >>> analysed this correctly. >>> >>> It seems that v’T’ * c_p * \rho would give us the correct units in [W/m^2]. >>> The c_p factor is trivial, but the density isn't. Since it is requested on >>> a specific pressure level, it would depend only on the temperature at 100 >>> hPa: \rho = 10^4 Pa/RT. This does add some nonlinearity. To do it >>> properly, you’d need the account for variations in \rho (T) in time and >>> space. >>> >>> Hence, would it be possible to keep the calculation as it is done by most >>> researchers as v’T’ and rename the variable to >>> >>> northward_temperature_flux_in_air_due_to_eddy_advection with units of [m K >>> s-1]. >>> >>> Also, by “eddy_advection”, people do mean deviations from the >>> instantaneous zonal mean. >>> >>> If it doesn’t sound like changing the name is a good idea, we could simply >>> change the units to [K m s-1], and explain that v’T’ was intended? >>> >>> This is what people expect to deliver for this variable as Gaelle’s case >>> shows too. >>> >>> >>> Michaela >>> >>> >>> >>> >>>> On 7 May 2019, at 09:30, Martin Juckes - UKRI STFC >>>> <martin.juc...@stfc.ac.uk> wrote: >>>> >>>> Hi Karl, >>>> >>>> >>>> It would need a new standard name .. perhaps : >>>> >>>> >>>> northward_heat_flux_expressed_as_temperature_flux_in_air_due_to_eddy_advection >>>> >>>> >>>> -- this is the current name with "_expressed_as_temperature_flux" >>>> inserted. It would make it clear that it is closely related to >>>> northward_heat_flux_in_air_due_to_eddy_advection, but also provide the >>>> necessary level of detail for CF. >>>> >>>> >>>> The relationship between the two is not a simple transformation of units: >>>> you need to make an assumption about the density and heat capacity of the >>>> air (if this is done after the fact it will, I believe, involve some >>>> degree of approximation). >>>> >>>> >>>> regards, >>>> >>>> Martin >>>> >>>> >>>> ________________________________ >>>> From: Taylor, Karl E. <taylo...@llnl.gov> >>>> Sent: 06 May 2019 16:34 >>>> To: Plummer, David (EC); Michaela Hegglin; Juckes, Martin (STFC,RAL,RALSP) >>>> Cc: David Neubauer; sen...@meteo.fr; RIGOUDY Gaelle; Michael Schulz >>>> Subject: Re: vt100 >>>> >>>> Hi Martin, >>>> >>>> It appears to me that perhaps more important than the inconsistency >>>> between standard_name and units, is the issue of whether or not to >>>> remove an instantaneous zonal-mean or a local time mean (or perhaps >>>> operate without removing any sort of mean). Since the heat flux is >>>> simply the temperture flux scaled by the specific heat of air at >>>> constant pressure with a value of about 1000 J kg-1 K-1, users can >>>> probably guess whether heat flux or temperature flux is actually being >>>> reported and correct for it. Users will not generally be able to guess >>>> whether deviations from some mean or full quantities are used in >>>> calculated the products. >>>> >>>> Since vt100 is used for a fairly specific "aerochem" diagnostic, I think >>>> they should decide what they *really* want (and need for their >>>> analysis). Then I think we should make an exception to our rule >>>> (because the science apparently demands it) and modify the data request >>>> to reflect this. If there is any way we can do this without changing >>>> the current standard_name for vt100, that would certainly be best >>>> because then all data would be searched for using the same standard >>>> name. The units would be inconsistent for some already written data >>>> sets, but errata could be recorded by es-docs for those models >>>> indicating the error in units. >>>> >>>> best regards, >>>> Karl >>>> >>>> >>>> On 5/4/19 3:28 PM, Plummer, David (EC) wrote: >>>>> Hi Michaela >>>>> I'll admit to being a bit out of my depth on stratopheric dynamics, >>>>> but from a practical standpoint looking at our diagnostic codes that were >>>>> developed by Charles McLandress we calculate the eddy meridional heat >>>>> flux as the product of the instantaneous deviations around the >>>>> instantaneous zonal average of the meridional velocity and temperature. >>>>> The end product is the zonal and monthly average of this product. This >>>>> calculation does agree with the description of V'T' in the literature >>>>> where the primes are used to denote deviations around the zonal mean. >>>>> Note that the MIP table for CCMI, which derives from the CCMVal data >>>>> request, has the following comment: Zonally averaged meridional heat >>>>> flux at 100 hPa as monthly means derived from daily (or higher frequency) >>>>> fields >>>>> It is really important that the sampling be daily or better because >>>>> you want to capture the meridional advection of temperature by transient >>>>> eddies. >>>>> It is one of the terms in the Transformed Eulerian Mean (TEM) >>>>> calculation of the stratospheric residual circulation and the value at >>>>> 100 hPa is usually seen as a proxy for the total amount of planetary wave >>>>> drag entering the stratosphere. Chapter 4 of the CCMVal report, >>>>> Stratospheric Dynamics, used the term 'eddy meridional heat flux' and >>>>> referenced a paper by Newman et al. (2001) where this term is referred to >>>>> similarly. I have also seen a few articles in the literature where it is >>>>> referred to as the 'temperature flux', so that term is not unknown. >>>>> David >>>>> >>>>> ________________________________________ >>>>> From: Michaela Hegglin <m.i.hegg...@reading.ac.uk> >>>>> Sent: May 4, 2019 6:23 AM >>>>> To: Martin Juckes - UKRI STFC; Plummer, David (EC) >>>>> Cc: Taylor Karl; David Neubauer; sen...@meteo.fr; RIGOUDY Gaelle; Michael >>>>> Schulz >>>>> Subject: Re: vt100 >>>>> >>>>> Hi all again, >>>>> >>>>> Indeed, our community was lax about the notation and commonly used 'heat >>>>> flux’ instead of the more correct term ’temperature flux’ (K m s-1), >>>>> which is a measure for wave activity. The units should remain [K m s-1]. >>>>> However, how to get the variable I am still not clear about. Hence, I >>>>> have copied in David Plummer who may be able to tell us what it is >>>>> exactly what was calculated in CCMVal for the temperature flux (whether >>>>> v’T’ or v’*T’ in fact as Martin says below). Then we have clear >>>>> instructions and should find the right notation for it. >>>>> >>>>> Thanks for looking into this, >>>>> >>>>> Michaela >>>>> >>>>> >>>>>> On 3 May 2019, at 15:47, Martin Juckes - UKRI STFC >>>>>> <martin.juc...@stfc.ac.uk> wrote: >>>>>> >>>>>> Hello Karl, >>>>>> >>>>>> >>>>>> do you have an idea what to do about this? >>>>>> >>>>>> >>>>>> The variable "vt100" has long name "Northward Heat Flux Due to Eddies", >>>>>> >>>>>> standard name: "northward_heat_flux_in_air_due_to_eddy_advection" and >>>>>> units "W m-2". >>>>>> >>>>>> >>>>>> AerChemMIP, who requested the variable, really wanted a meridional >>>>>> temperature flux (units "K m s-1") and at least one group (CNRM) has >>>>>> submitted temperature flux data with metadata as above saying it is a >>>>>> heat flux. >>>>>> >>>>>> >>>>>> At the moment only two groups have published vt100 data (CNRM and IPSL), >>>>>> but it is likely that many more have produced the data and are in the >>>>>> process of preparing it for publication. >>>>>> >>>>>> >>>>>> Michaela has suggested an "errata" for the data request, but I don't >>>>>> think this helps: if we decide to make a change, the easiest approach >>>>>> would be to update the request. The only reason for not doing this is >>>>>> that we have committed to not changing the definitions of variables -- >>>>>> but that is a significant reason. >>>>>> >>>>>> >>>>>> regards, >>>>>> >>>>>> Martin >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> ________________________________ >>>>>> From: Michaela Hegglin <m.i.hegg...@reading.ac.uk> >>>>>> Sent: 02 May 2019 16:23 >>>>>> To: Michael Schulz >>>>>> Cc: Juckes, Martin (STFC,RAL,RALSP); Taylor Karl; David Neubauer; >>>>>> sen...@meteo.fr; RIGOUDY Gaelle >>>>>> Subject: Re: vt100 >>>>>> >>>>>> Hi all, >>>>>> >>>>>> Thank you, Gaelle, for this helpful and important information. >>>>>> >>>>>> My rather limited understanding is that the fields that were defined and >>>>>> produced in CCMI could be converted in Wm-2 by integration of the fields >>>>>> involving air density and the heat capacity (cp), however, this would >>>>>> not be the fields that users would look for nor would know of how to >>>>>> use/interpret/compare to old studies easily. >>>>>> >>>>>> So, yes, Martin, if there is a way to remedy the problem with leaving >>>>>> the units but changing the standard name (or by putting a caveat around >>>>>> that variable used in CMIP6) that would be great… >>>>>> >>>>>> Michaela >>>>>> >>>>>> >>>>>>> On 2 May 2019, at 16:12, Michael Schulz <micha...@met.no> wrote: >>>>>>> >>>>>>> Hi Martin, >>>>>>> >>>>>>> I understand, sorry that this slipped our attention. >>>>>>> >>>>>>> for curiosity - what happens now? Shouldnt there be some log on errors >>>>>>> in the data request? >>>>>>> Or would you add a specific clarification to the data request that this >>>>>>> variable has been specified with an incompatible unit and standard name? >>>>>>> >>>>>>> best wishes >>>>>>> Michael >>>>>>> >>>>>>>> On 30 Apr 2019, at 13:44, Martin Juckes - UKRI STFC >>>>>>>> <martin.juc...@stfc.ac.uk> wrote: >>>>>>>> >>>>>>>> Hello Michaela, Michael, >>>>>>>> >>>>>>>> >>>>>>>> I'm afraid that is not consistent with the CF Convention. The standard >>>>>>>> name "northward_heat_flux_in_air_due_to_eddy_advection" is for a heat >>>>>>>> flux, so it needs to have units of "W m-2". >>>>>>>> >>>>>>>> >>>>>>>> It looks as though the term was declared in the CCMI tables with an >>>>>>>> invalid combination of "units" and "standard_name". In the CMIP6 >>>>>>>> request, the "units" have been modified to be consistent with the >>>>>>>> "standard_name". >>>>>>>> >>>>>>>> >>>>>>>> The variable "vt100" has already been published in CMIP6 (with units >>>>>>>> "W m-2") by IPSL and CNRM, Stéphane Senesi or Gaëlle Rigoudy (copied >>>>>>>> in) might be able to comment on how they did this (the question is: >>>>>>>> what factor is used to convert v*t into a heat flux? (see, for >>>>>>>> example, >>>>>>>> https://esg1.umr-cnrm.fr/thredds/dodsC/CMIP6_CNRM/CMIP/CNRM-CERFACS/CNRM-ESM2-1/amip/r1i1p1f2/AERmonZ/vt100/grz/v20181205/vt100_AERmonZ_CNRM-ESM2-1_amip_r1i1p1f2_grz_197901-201412.nc.html). >>>>>>>> >>>>>>>> >>>>>>>> If this issue had come up earlier we could have changed the standard >>>>>>>> name and the units ... but we have promised modeling centres not to >>>>>>>> change the definitions of variables (beyond clarifications) at this >>>>>>>> stage. >>>>>>>> >>>>>>>> >>>>>>>> regards, >>>>>>>> >>>>>>>> Martin >>>>>>>> >>>>>>>> ________________________________ >>>>>>>> From: Michaela Hegglin <m.i.hegg...@reading.ac.uk> >>>>>>>> Sent: 30 April 2019 10:30 >>>>>>>> To: Michael Schulz >>>>>>>> Cc: Juckes, Martin (STFC,RAL,RALSP); Neubauer David >>>>>>>> Subject: Re: vt100 >>>>>>>> >>>>>>>> Hi again, >>>>>>>> >>>>>>>> Here more information from David Plummer, I got the units wrong in my >>>>>>>> previous email. >>>>>>>> >>>>>>>> Hope this helps, >>>>>>>> >>>>>>>> Michaela >>>>>>>> >>>>>>>> >>>>>>>> variable_entry: vt100 >>>>>>>> !============ >>>>>>>> modeling_realm: atmos >>>>>>>> !---------------------------------- >>>>>>>> ! Variable attributes: >>>>>>>> !---------------------------------- >>>>>>>> standard_name: northward_heat_flux_in_air_due_to_eddy_advection >>>>>>>> units: K m s-1 >>>>>>>> cell_methods: time: mean longitude: mean >>>>>>>> long_name: Meridional Heat Flux >>>>>>>> comment: Zonally averaged meridional heat flux at 100 hPa as >>>>>>>> monthly means derived from daily (or higher frequency) fields. >>>>>>>> !---------------------------------- >>>>>>>> ! Additional variable information: >>>>>>>> !---------------------------------- >>>>>>>> dimensions: longitude latitude time pr100 >>>>>>>> type: real >>>>>>>> valid_min: -1000.0 >>>>>>>> valid_max: 1000.0 >>>>>>>> !---------------------------------- >>>>>>>> >>>>>>>> It is the zonal average of the product of V' x T', where the prime is >>>>>>>> the deviation around the zonal average. So the units you get are just >>>>>>>> windspeed (m s-1) times temperature (K) -> K m s-1. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> ******************************************** >>>>>>>> Michaela I. Hegglin >>>>>>>> Associate Professor in Atmospheric Chemistry >>>>>>>> Department of Meteorology >>>>>>>> University of Reading >>>>>>>> Lyle Building, 302A >>>>>>>> Reading, RG6 6BX, UK >>>>>>>> >>>>>>>> email m.i.hegg...@reading.ac.uk<mailto:m.i.hegg...@reading.ac.uk> >>>>>>>> phone +44 (0)118 378 6693 >>>>>>>> fax +44 (0)118 378 8905 >>>>>>>> ******************************************** >>>>>>>> >>>>>>>> On 29 Apr 2019, at 12:56, Michael Schulz >>>>>>>> <micha...@met.no<mailto:micha...@met.no>> wrote: >>>>>>>> >>>>>>>> Hi Michaela, >>>>>>>> >>>>>>>> Can you explain how this vt 100 is calculated? >>>>>>>> >>>>>>>> Its a ccmi variable in AerChemMIP... >>>>>>>> >>>>>>>> See below, >>>>>>>> Thanks >>>>>>>> Michael >>>>>>>> >>>>>>>> ------- Weitergeleitete Nachricht ------ >>>>>>>> Von: Neubauer David >>>>>>>> <david.neuba...@env.ethz.ch<mailto:david.neuba...@env.ethz.ch>> >>>>>>>> Datum: Mo. 29. Apr. 2019 um 11:11 >>>>>>>> Betreff: RE: vt100 >>>>>>>> An: Martin Juckes - UKRI STFC >>>>>>>> <martin.juc...@stfc.ac.uk<mailto:martin.juc...@stfc.ac.uk>>, Michael >>>>>>>> Schulz <micha...@met.no<mailto:micha...@met.no>> >>>>>>>> Cc: Ferrachat Sylvaine >>>>>>>> <sylvaine.ferrac...@env.ethz.ch<mailto:sylvaine.ferrac...@env.ethz.ch>> >>>>>>>> >>>>>>>> >>>>>>>> Hi Michael and Martin, >>>>>>>> >>>>>>>> we would like to start our simulations soon. Therefore we would need >>>>>>>> to know possible pre-factors of "vt100". Thank you for any help you >>>>>>>> can provide. >>>>>>>> >>>>>>>> Kind regards, >>>>>>>> David >>>>>>>> >>>>>>>>>> -----Original Message----- >>>>>>>>>> From: Martin Juckes - UKRI STFC >>>>>>>>>> [mailto:martin.juc...@stfc.ac.uk<mailto:martin.juc...@stfc.ac.uk>] >>>>>>>>>> Sent: Freitag, 12. April 2019 17:10 >>>>>>>>>> To: Michael Schulz >>>>>>>>>> Cc: Neubauer David >>>>>>>>>> Subject: Fw: vt100 >>>>>>>>>> >>>>>>>>>> Hello Michael, >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Can you help with David's question below about the precise >>>>>>>>>> definition of >>>>>>>>>> the "vt100" variable requested by AerChemMIP? >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> regards, >>>>>>>>>> >>>>>>>>>> Martin >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> ________________________________ >>>>>>>>>> From: Neubauer David >>>>>>>>>> <david.neuba...@env.ethz.ch<mailto:david.neuba...@env.ethz.ch>> >>>>>>>>>> Sent: 12 April 2019 15:39 >>>>>>>>>> To: Juckes, Martin (STFC,RAL,RALSP) >>>>>>>>>> Cc: Ferrachat Sylvaine >>>>>>>>>> Subject: vt100 >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Dear Martin, >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> In the CMIP6 data request it is written that the units for the >>>>>>>>>> variable vt100 >>>>>>>>>> (AERmonZ) should be [W m-2]. However, computing the zonal average of >>>>>>>>>> the product of the zonal average departures of v and t has the units >>>>>>>>>> [m s-1 >>>>>>>>>> K-1]. By which factors should this product be multiplied to obtain >>>>>>>>>> the zonally >>>>>>>>>> meridional averaged heat flux? >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Thank you in advance for any help you can provide. >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Kind regards, >>>>>>>>>> >>>>>>>>>> David >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> -- >>>>>>>>>> Dr. David Neubauer >>>>>>>>>> ETH Zurich >>>>>>>>>> Institute for Atmospheric and Climate Science Universitaetstrasse >>>>>>>>>> 16, CHN >>>>>>>>>> P17.2 >>>>>>>>>> 8092 Zurich, Switzerland >>>>>>>>>> phone: +41 44 632 74 26 >>>>>>>>>> >> _______________________________________________ >> CF-metadata mailing list >> CF-metadata@cgd.ucar.edu >> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > ----- End forwarded message ----- > > ----- End forwarded message ----- > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
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