new standard names proposed for `uqint` and `vqint` (was: potential issue with unit of uqint and vqint)

[oligan]

I think there is an issue with the unit declared for variables uqint and vqint.

uqint:long_name = "integrated_eastward_wind_times_humidity" ; uqint:units = "m2 s-1" ; uqint:standard_name = "integral_of_product_of_eastward_wind_and_specific_humidity_wrt_height" ; uqint:description = "Eastward integrated moisture transport" ;

uqint corresponds to the flux of specific humidity through a vertical surface (from surface to top-of-atmosphere along the latitude). The specific humidity should be weighted by the air density (this is natural although not explicitly stated). The unit is thus kg water/kg air (q) kg air/m3 (rho_air) m/s (ua) * m (dz) = kg water m-1 s-1, ie it is the quantity of water going through one unit distance in latitude per unit time.

I am not sure where the unit m2/s comes from. Maybe it includes a conversion factor due to the water density (1000 kg/m3), in which case the kg/m/s unit could be equivalent to 10^-3 m3 water / m / s or 10^-3 m2/s.

However this would be very confusing and the natural unit for uqint and vqint is really kg/m/s.

Anyone disagrees?

Olivier Boucher, IPSL

[taylor13]

I agree with Olivier that the natural units (that I would use) are kg water m-1 s-1. Could we find out who originally proposed the standard_name and ask why different units were specified (and how the integral is actually calculated?

[oligan]

There does not seem to be disagreement on this. Can this then be corrected?

[github-actions[bot]]

Thank you for your proposal. These terms will be added to the cfeditor (http://cfeditor.ceda.ac.uk/proposals/1) shortly. Your proposal will then be reviewed and commented on by the community and Standard Names moderator.

[larsbarring]

I have just added labels "defect", "standard name", and "moderator attention" manually (I hope that this does not upset the template automation).

[JonathanGregory]

I think that with the given standard name integral_of_product_of_eastward_wind_and_specific_humidity_wrt_height the correct canonical units is m s-1 1 m = m2 s-1 as given. Maybe this isn't what was intended, though. If it's supposed to be multiplied by density to give units of kg m-1 s-1, the standard name should be integral_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air_wrt_height i.e. m s-1 kg m-3 m. Probably integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air would be clearer.

[OB-IPSL]

Hi Jonathan, nice to hear from you and glad that we're getting the ball rolling on this issue. I take your point that the unit is correct for the integral over height of specific humidity but this variable is pointless and confusing (I hope you agree with this). What would be the process to get this right? Is it possible to modify the standard name, as well or should the variable be unpublished and republished properly? Olivier

[JonathanGregory]

Dear Olivier @OB-IPSL

It's nice to hear from you too.

Someone must have had a use-case for this quantity and standard name (I don't know when), otherwise we wouldn't have added it. Therefore we must retain it in the table, for the sake of any existing data if nothing else. A design principle of CF is that conventions are "provided to allow data-producers to describe the data they wish to produce, rather than attempting to prescribe what data they should produce", and I suppose someone wanted to produce this quantity!

However, we can of course add new standard names for the quantities in kg m-1 s-1, if that would be better for uqint and vqint. Are these CMIP variables? If so, I suppose it means either that existing data is not what was really intended, or that it's been written with the wrong units attribute. We can't repair the damage in either case, but we can stop it happening in future.

Best wishes

Jonathan

[OB-IPSL]

yes, it is a CMIP6 variable. Few groups have provided it but I see UK-ESM and HadGEM have, maybe you can have a look at what they did. Usually this variable is there to quantify the latitudinal and longitudinal fluxes of water vapour.

[taylor13]

Yes, some model versions labeled CNRM, HadGEM, IPSL, and UKESM have all produced vqint, and a subset of the model versions have also contributed uqint.

They were requested by HighResMIP, so we could contact them to see why they wanted this quantity.

Jonathan is, of course, right that the units are appropriate for the standard name, and the question is should we be requesting a different quantity. I can't see how the vertical integral of vqdz would be of any interest to anyone (where v=velocity, q=specific humidity, and z=height). On the other hand, the vertical integral of (v q rho dz) = (v q dp/g) provides a good measure of horizontal transport of water (integrated through the atmospheric column), where rho=the density of air, p is pressure, and g the acceleration of gravity. I think this is what CMIP7 should request (if any of the MIPs is still interested).

I like Jonathan's "clearer" name for the integral of (v q rho dz): integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air

[taylor13]

Yes, some model versions labeled CNRM, HadGEM, IPSL, and UKESM have all produced vqint, and a subset of the model versions have also contributed uqint.

They were requested by HighResMIP, so we could contact them to see why they wanted this quantity.

Jonathan is, of course, right that the units are appropriate for the standard name, and the question is should we be requesting a different quantity. I can't see how the vertical integral of vqdz would be of any interest to anyone (where v=velocity, q=specific humidity, and z=height). On the other hand, the vertical integral of (v q rho dz) = (v q dp/g) provides a good measure of horizontal transport of water (integrated through the atmospheric column), where rho=the density of air, p is pressure, and g the acceleration of gravity. I think this is what CMIP7 should request (if any of the MIPs is still interested).

I like Jonathan's "clearer" name for the integral of (v q rho dz): integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air

[Also, just to note that the standard name for vqint in the CMIP6 data request is consistent with the standard name in the CF conventions listing, namely: integral_wrt_height_of_product_of_northward_wind_and_specific_humidity. The standard name in Olivier's original comment above is listed as an alias in the standard names table.]

[OB-IPSL]

OK so if I understand correctly, the CF folks have to define new quantities integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air and integral_wrt_height_of_product_of_northward_wind_and_mass_concentration_of_water_vapor_in_air with the unit kg/m/s. I don't know what the procedure is to request this. Then the CMIP folks (Martin in practice) has to redefine uqint and vqint in the next version of the CMIP Climate Data Request. Right ?

[JonathanGregory]

Dear Olivier @OB-IPSL

Yes, I think that's right. You could request the standard names in this issue, if you propose the names, units and description. Alternatively you could open a new issue in this repo for the proposal, and close this one. Thanks for raising it.

Best wishes

Jonathan

[OB-IPSL]

Thanks Jonathan. I follow up on this to request the addition of two standard names in the CF convention:

standard name: integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air unit: kg m-1 s-1 description: Eastward vertically-integrated moisture flux per unit length in latitude

standard name: integral_wrt_height_of_product_of_northward_wind_and_mass_concentration_of_water_vapor_in_air unit: kg m-1 s-1 description: Northward vertically-integrated moisture flux per unit length in longitude

Is that all you need ?

Thanks to everyone involved

Olivier

[JonathanGregory]

Yes, I think that's fine, Olivier. Thanks. The moderators of standard name will reply in due course.

[efisher008]

Hi @OB-IPSL,

I have added the new standard names proposed on 2023-10-25 to the CF editor, visible by searching here: https://cfeditor.ceda.ac.uk/proposals/1. We have an existing standard name "integral_wrt_time_of_surface_downward_turbulent_heat_flux" which these names appear to conform to the same formatting as. But I might suggest that "integral_wrt" suggests a transformation of Y wrt X, which is recommended in the guidelines to be expressed as "integral_of_Y_wrt_X". I can see that @JonathanGregory has previously commented on this:

_> I think that with the given standard name integral_of_product_of_eastward_wind_and_specific_humidity_wrt_height the correct canonical units is m s-1 1 m = m2 s-1 as given. Maybe this isn't what was intended, though. If it's supposed to be multiplied by density to give units of kg m-1 s-1, the standard name should be integral_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air_wrt_height i.e. m s-1 kg m-3 m. Probably integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air would be clearer._

Is this the consensus that you reached?

Other standard name guidelines have been followed (lower case, US spelling, underscores separating all words etc.). I will wait for further discussion on this and comments by other moderators @japamment or @feggleton. Thank you for your patience!

Best wishes, Ellie

[OB-IPSL]

Dear Ellie, the consensus is as per my last post from last week. Whether your put the wrt_toheight after the integral or at the end of the standard name is really up to you and according to what your guidelines say. It doesn't change the description or the meaning of two variables.
Thanks to you and to the moderators for their forthcoming feedbacks. Best regards

[efisher008]

Dear Olivier,

Thank you for your comment. I will wait for others to weigh in on this.

Best regards, Ellie

[efisher008]

Hello Olivier,

As there has been no further discussion on this issue for a while, I think that the best course of action here is to publish the standard names as you suggest in the 29-10-2023 proposal, i.e. integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air and integral_wrt_height_of_product_of_northward_wind_and_mass_concentration_of_water_vapor_in_air respectively. I will do this within the next week if there are no issues/alternative suggestions. Thank you for your patience and sorry for the long wait!

Best, Ellie

[efisher008]

There are also some suggested phrases from the CF phrase bank which I think would benefit from being included in the description. These are the following:

For eastward name - _"Eastward" indicates a vector component which is positive when directed eastward (negative westward). Height is the vertical distance above the surface. Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name "upward_air_velocity"). The phrase "product_of_X_and_Y" means X*Y. The abbreviation "wrt" means "with respect to". The phrase "integral_wrt_X_of_Y" means int Y dX. To specify the limits of the integral the data variable should have an axis for X and associated coordinate bounds. If no axis for X is associated with the data variable, or no coordinate bounds are specified, it is assumed that the integral is calculated over the entire vertical extent of the medium, e.g, if the medium is air the integral is assumed to be calculated over the full depth of the atmosphere. "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y. A chemical species or biological group denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_asnitrogen".

For northward name - _"Northward" indicates a vector component which is positive when directed northward (negative southward). Height is the vertical distance above the surface. Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name "upward_air_velocity"). The phrase "product_of_X_and_Y" means X*Y. The abbreviation "wrt" means "with respect to". The phrase "integral_wrt_X_of_Y" means int Y dX. To specify the limits of the integral the data variable should have an axis for X and associated coordinate bounds. If no axis for X is associated with the data variable, or no coordinate bounds are specified, it is assumed that the integral is calculated over the entire vertical extent of the medium, e.g, if the medium is air the integral is assumed to be calculated over the full depth of the atmosphere. "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y. A chemical species or biological group denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_asnitrogen".

If there are no objections, these can go in the descriptions for those names.

[oligan]

Dear Ellie,I was wondering yesterday where we stood on this, so your email was very timely !I agree on the proposed additions. The last sentence is not as relevant as the rest but it is fine to keep it as well. Thank you again,All the best, Olivier  De: "Ellie Fisher" @.>À: "cf-convention/discuss" @.>Cc: "Olivier Boucher" @.>, "Author" @.>Envoyé: Mardi 9 Janvier 2024 17:03:33Objet: Re: [cf-convention/discuss] new standard names proposed for uqint and vqint (was: potential issue with unit of uqint and vqint) (#83) There are also some suggested phrases from the CF phrase bank which I think would benefit from being included in the description. These are the following: For eastward name - "Eastward" indicates a vector component which is positive when directed eastward (negative westward). Height is the vertical distance above the surface. Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name "upward_air_velocity"). The phrase "product_of_X_and_Y" means XY. The abbreviation "wrt" means "with respect to". The phrase "integral_wrt_X_of_Y" means int Y dX. To specify the limits of the integral the data variable should have an axis for X and associated coordinate bounds. If no axis for X is associated with the data variable, or no coordinate bounds are specified, it is assumed that the integral is calculated over the entire vertical extent of the medium, e.g, if the medium is air the integral is assumed to be calculated over the full depth of the atmosphere. "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y. A chemical species or biological group denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". For northward name - "Northward" indicates a vector component which is positive when directed northward (negative southward). Height is the vertical distance above the surface. Wind is defined as a two-dimensional (horizontal) air velocity vector, with no vertical component. (Vertical motion in the atmosphere has the standard name "upward_air_velocity"). The phrase "product_of_X_and_Y" means XY. The abbreviation "wrt" means "with respect to". The phrase "integral_wrt_X_of_Y" means int Y dX. To specify the limits of the integral the data variable should have an axis for X and associated coordinate bounds. If no axis for X is associated with the data variable, or no coordinate bounds are specified, it is assumed that the integral is calculated over the entire vertical extent of the medium, e.g, if the medium is air the integral is assumed to be calculated over the full depth of the atmosphere. "Mass concentration" means mass per unit volume and is used in the construction "mass_concentration_of_X_in_Y", where X is a material constituent of Y. A chemical species or biological group denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". If there are no objections, these can go in the descriptions for those names.

—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: @.***>

[efisher008]

Dear @oligan,

I have now added the text we agreed and accepted the two standard names integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air and integral_wrt_height_of_product_of_northward_wind_and_mass_concentration_of_water_vapor_in_air. Thanks again for the discussion and your patience with this!

Best regards, Ellie

[oligan]

Thank you very much. I guess Martin Juckes can take it from here, as we need to change the variable names in the Climate Data Request of CMIP Best regards, Olivier

Le 15 janv. 2024 à 12:26, Ellie Fisher @.***> a écrit :

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Dear [ https://github.com/oligan | @oligan ] ,

I have now added the text we agreed and accepted the two standard names integral_wrt_height_of_product_of_eastward_wind_and_mass_concentration_of_water_vapor_in_air and integral_wrt_height_of_product_of_northward_wind_and_mass_concentration_of_water_vapor_in_air . Thanks again for the discussion and your patience with this!

Best regards, Ellie

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[efisher008]

These names were published in January 2024 in v84 of the standard names table.