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[CF-metadata] Suggestion for standard names for bottom current and due to tides and Stokes drift

From: Francesca Eggleton - UKRI STFC <francesca.eggleton>
Date: Mon, 11 Nov 2019 17:29:31 +0000

Dear Marcelo,



Thank you for your proposals and apologies for the delay in responding. As you may have seen in Alison's last email, I will be helping out with the maintenance of the standard names.



Thank you to Jonathan for comments on these proposals. They all look good and seem to match what already exists. The two phrases which were suggested as aliases, I believe to be new terms and have suggested a reason why so please comment if you agree/disagree. The following text will list each of the proposals, their units and descriptions (constructed from similar terms to be in line with standard name descriptions). Please let me know if there are any comments or further changes to be made. If no comments are made in the next 7 days, these are likely to be accepted in the next update.

eastward_sea_water_velocity_at_sea_floor
ms-1
A velocity is a vector quantity. "Eastward" indicates a vector component which is positive when directed eastward (negative westward). The velocity at the sea floor is that adjacent to the ocean bottom, which would be the deepest grid cell in an ocean model.

northward_sea_water_velocity_at_sea_floor
ms-1
A velocity is a vector quantity. "Northward" indicates a vector component which is positive when directed northward (negative southward). The velocity at the sea floor is that adjacent to the ocean bottom, which would be the deepest grid cell in an ocean model.

sea_water_to_direction_at_sea_floor
degree
The phrase "to_direction" is used in the construction X_to_direction and indicates the direction towards which the velocity vector of X is headed. The direction is a bearing in the usual geographical sense, measured positive clockwise from due north. The direction at the sea floor is that adjacent to the ocean bottom, which would be the deepest grid cell in an ocean model.

sea_water_speed_at_sea_floor
ms-1
Speed is the magnitude of velocity. The speed at the sea floor is that adjacent to the ocean bottom, which would be the deepest grid cell in an ocean model.

eastward_sea_water_velocity_due_to_tides
ms-1
A velocity is a vector quantity. "Eastward" indicates a vector component which is positive when directed eastward (negative westward). The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Due to tides" means due to all astronomical gravity changes which manifest as tides. No distinction is made between different tidal components.
northward_sea_water_velocity_due_to_tides
ms-1
A velocity is a vector quantity. "Northward" indicates a vector component which is positive when directed northward (negative southward). The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Due to tides" means due to all astronomical gravity changes which manifest as tides. No distinction is made between different tidal components.

sea_water_to_direction_due_to_tides
degree
The phrase "to_direction" is used in the construction X_to_direction and indicates the direction towards which the velocity vector of X is headed. The direction is a bearing in the usual geographical sense, measured positive clockwise from due north. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Due to tides" means due to all astronomical gravity changes which manifest as tides. No distinction is made between different tidal components.

sea_water_speed_due_to_tides
ms-1
Speed is the magnitude of velocity. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Due to tides" means due to all astronomical gravity changes which manifest as tides. No distinction is made between different tidal components.

The following should not be aliases of sea_surface_wave_stokes_drift_x_velocity and sea_surface_wave_stokes_drift_y_velocity, they should be proposed as new terms. The definition states '"x" indicates a vector component along the grid x-axis, positive with increasing x.', this has been done on purpose to allow this term to be used with any type of grid and not limiting it to a lat-lon grid. The term eastward is defined as '"Eastward" indicates a vector component which is positive when directed eastward (negative westward)' which limits this term to being 'zonal' (along a latitudinal circle).

sea_surface_wave_stokes_drift_eastward_velocity
ms-1
A velocity is a vector quantity. "Eastward" indicates a vector component which is positive when directed eastward (negative westward). The Stokes drift velocity is the average velocity when following a specific fluid parcel as it travels with the fluid flow. For instance, a particle floating at the free surface of water waves, experiences a net Stokes drift velocity in the direction of wave propagation.

sea_surface_wave_stokes_drift_northward_velocity
ms-1
A velocity is a vector quantity. "Northward" indicates a vector component which is positive when directed northward (negative southward). The Stokes drift velocity is the average velocity when following a specific fluid parcel as it travels with the fluid flow. For instance, a particle floating at the free surface of water waves, experiences a net Stokes drift velocity in the direction of wave propagation.


sea_surface_wave_stokes_drift_to_direction
degrees
The Stokes drift velocity is the average velocity when following a specific fluid parcel as it travels with the fluid flow. For instance, a particle floating at the free surface of water waves, experiences a net Stokes drift velocity in the direction of wave propagation. The phrase "to_direction" is used in the construction X_to_direction and indicates the direction towards which the velocity vector of X is headed. The direction is a bearing in the usual geographical sense, measured positive clockwise from due north.


sea_surface_wave_stokes_drift_speed

ms-1

The Stokes drift velocity is the average velocity when following a specific fluid parcel as it travels with the fluid flow. For instance, a particle floating at the free surface of water waves, experiences a net Stokes drift velocity in the direction of wave propagation. Speed is the magnitude of velocity.



Thank you,

Francesca Eggleton
Graduate Environmental Data Scientist
Normal Working Hours (Mon-Thurs): 9am-5pm (Fri 4:30pm)
RAL Space | R25 | Ext: 6710

Centre for Environmental Data Analysis (CEDA)
Science and Technology Facilities Council (STFC)
Rutherford Appleton Laboratory | Harwell Campus
Didcot | OX11 0QX
www.ceda.ac.uk<http://www.ceda.ac.uk/>


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P Please consider the environment before printing this e-mail



Dear Marcelo



These look fine to me, thanks. Just to be clear - you're *not* proposing

at_bottom, are you? I agree with you that at_sea_floor would be the right

phrase to use.



Best wishes



Jonathan





Hello,



I would like to suggest the inclusion of standard names for u, v,

speed and direction for bottom current and due to tides and Stokes

drift:



An example of model output with bottom velocity is the HYCOM NCODA forecast:

https://tds.hycom.org/thredds/catalog/GLBv0.08/expt_93.0/data/forecasts/runs/catalog.html?dataset=GLBv0.08/expt_93.0/data/forecasts/runs/FMRC_RUN_2019-10-13T12:00:00Z

water_u_bottom (m/s) = Eastward Water Velocity =

eastward_sea_water_velocity_at_bottom

water_v_bottom (m/s) = Northward Water Velocity =

northward_sea_water_velocity_at_bottom



based on existing variables:

sea_water_potential_temperature_at_sea_floor

sea_water_temperature_at_sea_floor

sea_water_salinity_at_sea_floor

sea_water_pressure_at_sea_floor



my suggestion would be:

eastward_sea_water_velocity_at_sea_floor

northward_sea_water_velocity_at_sea_floor

sea_water_to_direction_at_sea_floor

sea_water_speed_at_sea_floor



An example of model output with currents due to tides and Stokes drift

is the Mercator Forecast:

http://marine.copernicus.eu/services-portfolio/access-to-products/?option=com_csw&view=details&product_id=GLOBAL_ANALYSIS_FORECAST_PHY_001_024



based on existing variables:

eastward_sea_water_velocity_assuming_no_tide

northward_sea_water_velocity_assuming_no_tide

ocean_vertical_momentum_diffusivity_due_to_tides

ocean_vertical_tracer_diffusivity_due_to_tides



my suggestion would be:

eastward_sea_water_velocity_due_to_tides

northward_sea_water_velocity_due_to_tides

sea_water_to_direction_due_to_tides

sea_water_speed_due_to_tides



Stokes drift is present in the current CF table with:

sea_surface_wave_stokes_drift_x_velocity

sea_surface_wave_stokes_drift_y_velocity

I think it could help to add

sea_surface_wave_stokes_drift_eastward_velocity

sea_surface_wave_stokes_drift_northward_velocity

as aliases to make it clear it is zonal and meridional currents, and

not just along the grid X and Y dimensions.



Thank you very much.

--
Marcelo Andrioni
marceloandrioni at gmail.com<http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata>
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Received on Mon Nov 11 2019 - 10:29:31 GMT

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