Dear Jonathan,
This is a citation of the CF standard
> The surface called "surface" means the lower boundary of the atmosphere. "Water" means water in all phases, including frozen i.e. ice and snow. A velocity is a vector quantity. "Eastward" indicates a vector component which is positive when directed eastward (negative westward). < (http://cfconventions.org/Data/cf-standard-names/28/build/cf-standard-name-table.html)
In our model we distinguish between ice velocity and the water velocity under the ice in addition to the (average) water velocity in the upper layer. Guess we would be fine if surface_eastward_sea_water_velocity and surface_northward_sea_water_velocity would not include ice per definition.
With kind regards / med vennlig hilsen,
Ute
Ute Br?nner
Research Scientist & Senior Project Manager
Direct phone (+47) 998 98 987
? ?Consider the environment before printing. Less print-outs, more trees, better planet.
-----Original Message-----
From: CF-metadata [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Gregory
Sent: 01 June 2017 14:39
To: cf-metadata at cgd.ucar.edu
Subject: [CF-metadata] standard names under ice velocity of water
Dear Ute
I share some of Roy's concerns, and I'm puzzled by your remark:
> surface_eastward_sea_water_velocity and
> surface_northward_sea_water_velocity
> include the velocity of water and ice together
Please could you explain what that means? Are the ice and water moving with the same velocity or not?
I think it may be OK to have a stdname for the "surface" velocity for sea water, because there isn't a unique coordinate with which to label the surface.
For the same reason, we have a standard name of surface_temperature.
For the "underice" velocity of sea water, if this is different from the surface velocity, it would be better to use the phrase at_sea_ice_base, for consistency with several existing standard names containing that phrase.
Best wishes
Jonathan
----- Forwarded message from "Lowry, Roy K." <rkl at bodc.ac.uk> -----
> Date: Wed, 31 May 2017 07:58:02 +0000
> From: "Lowry, Roy K." <rkl at bodc.ac.uk>
> To: Ute Br?nner <Ute.Broenner at sintef.no>, "cf-metadata at cgd.ucar.edu"
> <cf-metadata at cgd.ucar.edu>
> CC: Tor Nordam <Tor.Nordam at sintef.no>, Morten Omholt Alver
> <Morten.Alver at sintef.no>, Petter R?nningen
> <Petter.Ronningen at sintef.no>
> Subject: Re: [CF-metadata] standard names under ice velocity of water
>
> Dear Ute,
>
>
> There is a precedent in CF for not giving separate Standard Names to a single geophysical variable solely on the basis of its spatial distribution, the classic example being air temperature where the meteorological standard measurement '2m air temperature' has not been given its own Standard Name.
>
>
> I am also strongly against separate Standard Names for 'surface' unless they represent unique phenomena as has been argued for sea temperature and sea surface velocity.
>
>
> To me assigning separate Standard Names to currents in the top x metres of water that happens to be under ice sets a very dangerous precedent. If you decide to add extra water body layers to your model - say 10-50m, and 50-100m would you want different Standard Names for the currents in each of these?
>
>
> I can see two possible solutions to your problem of semantically differentiating the two water body layers in your model.
>
>
> 1) Use the long name parameter attribute
>
> 2) Include a z co-ordinate variable to describe each layer
>
>
> A third option would be to do both (1) and (2).
>
>
> Cheers, Roy.
>
>
>
>
> Please note that I partially retired on 01/11/2015. I am now only working 7.5 hours a week and can only guarantee e-mail response on Wednesdays, my day in the office. All vocabulary queries should be sent to enquiries at bodc.ac.uk. Please also use this e-mail if your requirement is urgent.
>
>
> ________________________________
> From: Ute Br?nner <Ute.Broenner at sintef.no>
> Sent: 31 May 2017 08:24
> To: Lowry, Roy K.; cf-metadata at cgd.ucar.edu
> Cc: Petter R?nningen; Morten Omholt Alver; Tor Nordam
> Subject: RE: [CF-metadata] standard names under ice velocity of water
>
>
> Dear Roy,
>
>
>
> I think it's because of the fact that in the upper layer (10m or so) we may have all four of them :
>
>
>
> 1) surface_eastward_sea_water_velocity and surface_northward_sea_water_velocity for water AND ice
>
> This is already a standard name with the definition that >"Water" means water in all phases"< so we can't use it for water only.
>
> 2) eastward_sea_ice_velocity and northward_sea_ice_velocity is the one we use for the ice only
>
>
>
> and
>
>
>
> 3) underice_eastward_sea_water_velocity and underice_northward_sea_water_velocity we propose for the water under the ice which is different from
>
>
>
> 4) eastward_sea_water_velocity and northward_sea_water_velocity which we use for the water body that is not at the surface (as the layer has several meters).
>
>
>
> We use the data for modelling of substances at the surface in the ice, so the separation of these data is important to us.
>
>
>
>
>
> With kind regards / med vennlig hilsen,
>
> Ute
>
>
>
> Ute Br?nner
>
> Research Scientist & Senior Project Manager
>
>
>
> Direct phone (+47) 998 98 987
>
> P Consider the environment before printing. Less print-outs, more trees, better planet.
>
>
>
> From: Lowry, Roy K. [mailto:rkl at bodc.ac.uk]
> Sent: 30 May 2017 17:50
> To: Ute Br?nner <Ute.Broenner at sintef.no>; cf-metadata at cgd.ucar.edu
> Cc: Petter R?nningen <Petter.Ronningen at sintef.no>; Morten Omholt Alver
> <Morten.Alver at sintef.no>; Tor Nordam <Tor.Nordam at sintef.no>
> Subject: Re: [CF-metadata] standard names under ice velocity of water
>
>
>
> Dear Ute,
>
>
>
> I would prefer the same Standard Name for the currents in a body of water whether or not it is covered by ice. What happens if you have a full year of data from a position where there is only ice for part of the year? Would you have a change of Standard Name for the water body currents when the ice melts?
>
>
>
> So, why not use 'eastward_sea_water_velocity' and 'northward_sea_water_velocity'?
>
>
>
> Cheers, Roy.
>
>
>
> Please note that I partially retired on 01/11/2015. I am now only working 7.5 hours a week and can only guarantee e-mail response on Wednesdays, my day in the office. All vocabulary queries should be sent to enquiries at bodc.ac.uk<mailto:enquiries at bodc.ac.uk>. Please also use this e-mail if your requirement is urgent.
>
>
>
> ________________________________
>
> From: CF-metadata
> <cf-metadata-bounces at cgd.ucar.edu<mailto:cf-metadata-bounces at cgd.ucar.
> edu>> on behalf of Ute Br?nner
> <Ute.Broenner at sintef.no<mailto:Ute.Broenner at sintef.no>>
> Sent: 30 May 2017 15:39
> To: cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>
> Cc: Petter R?nningen; Morten Omholt Alver; Tor Nordam
> Subject: [CF-metadata] standard names under ice velocity of water
>
>
>
> Hei from Norway!
>
> Our institute produces metocean data including currents and ice with
> the variables
>
> eastward_sea_ice_velocity and northward_sea_ice_velocity
> surface_eastward_sea_water_velocity and
> surface_northward_sea_water_velocity
>
> The latter include the velocity of water and ice together:
> "Water" means water in all phases, including frozen i.e. ice and snow. A velocity is a vector quantity. "Eastward" indicates a vector component which is positive when directed eastward (negative westward).
>
> We are also storing the velocity of water under the ice (which one
> could assume as the difference of the two above, slightly more complicated I think). What would be the standard name for that velocity? If there isn't any yet, may we propose underice_eastward_sea_water_velocity and underice_northward_sea_water_velocity?
>
> With kind regards / med vennlig hilsen, Ute
>
> Ute Br?nner
> Research Scientist & Senior Project Manager
>
> SINTEF Ocean
> Environmental Technology, Monitoring and Modelling
> www.sintef.no/DREAM<http://www.sintef.no/DREAM>,
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> ? Consider the environment before printing. Less print-outs, more trees, better planet.
>
>
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