Table 1-01-01, Revision of winds variables

[JohnEyre]

Proposal Summary

The wind variables in WMDR - 12005, 12006, 310, 307 - are inconsistent and incomplete. They should be revised to include:

• wind specified in speed and direction or in components,
• wind at a single level or a vector of levels,
• wind at specified heights or pressures, or at specified distances from reference levels,
• more complete definition of wind direction - an angle measured clockwise from North.

Summary and Purpose

Update and add variables to adequately support wind measurements.

Proposal

Update the existing wind variables and add new ones as necessary

Current Observed Variable Measurand Code

Notation	Name	Description
12005	Horizontal wind direction at specified distance from reference surface	the direction of Horizontal wind direction at specified distance from reference surface
12006	Horizontal Wind Speed	Horizontal wind speed at specified distance from reference surface
New	u (u component of horizontal wind vector)
New	v (v component of horizontal wind vector)
307	Wind (Z component vertical)	Z component of wind vector (horizontal and vertical profile)

Recommend removing 310 as it is not meaningful without definition of XY coordinates.

Reason

[your reasoning why the proposal resolves the issue]

Stakeholder(s)

ET-UAT
ET-SSU

Consultations

[include names and emails or handles of individuals or groups that reviewed the proposal]

Context

[include references to manuals or guides that are reviewed to ensure alignment, if proposal differs then document how and why]

Expected Impact of Change

[enter LOW (for editorial changes to existing codes), MEDIUM (for new codes) or HIGH (for deprecated and superseded codes]

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/Meeting-2022.09.22 notes:

• team agrees to follow up 
• @gaochen-larc will work on this
• @amilan17 reach out to ET-Upper Air Measurements?

[gaochen-larc]

I think we need five basic variables: wind direction, wind speed, u, v, and w. The vertical profile of wind can be described using attributes in the upcoming WMDR 2.0. The existing codes, i.e., 12005, 12006, 310, and 307, look confusing to me. Would like to see if and how they have been used. However, it would be rather difficult to update the description with additional information. Looking for comments and suggestions!

[gaochen-larc]

Wind Speed: commonly refer to the speed of horizontal wind, a ratio of the distance covered by the air to the time taken to cover it. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates

Wind Direction: the direction of horizontal wind expressed in degrees at which the wind originates, i.e., 0° for north or northerly wind, 90° for east or easterly wind, 180° (or -180°) degree for south or southerly wind, and 270° (or -90°) for west or westerly wind. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates

u: east-west component of the horizontal wind vector, positive value for eastward wind or west wind. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates

v: north-south component of the horizontal wind vector, positive value for northward wind or south wind . This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates.

w: vertical component of the 3-D wind vector. positive value for upward wind, This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates.

Looking comments and suggestions!

[mshook2012]

A few follow-up thoughts on @gaochen-larc's comments:

• The definition of wind speed should specify that it refers to the horizontal direction only (similar to the current 12006), i.e., sqrt(u^2 + v^2). I would suggest modifying it to "Ratio of the horizontal distance covered by air..."
• The terms used for directional winds here are somewhat confusing (e.g., for "positive value for eastward wind or west wind", it's not very clear that those are the same thing). I recommend replacing all references to directional winds with a more explicit from/to terminology (i.e., "positive value for wind blowing from west to east").
• For definitions of wind in a meteorological context, it might make sense to include a definition for the vertical velocity variable ω = dp/dt in addition to w = dz/dt.
• It may be worth noting that in most cases, wind direction is measured as clockwise from TRUE (geographic) north. However, there are situations in which wind direction is reported with respect to MAGNETIC north (e.g., for aviation purposes; see this FAA publication, Section 4-3-6a).

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2022.10.06-TT-WIGOSMD meeting notes:

Comment from Michael Shoot (NASA) above; in progress

[amilan17]

Sent email to secretariat that supports ET-UAM to find a volunteer to review.

[joergklausen]

@amilan17 Could you update the issue to reflect the discussion, so that we see what is specifically proposed?

[jrb08j]

Wind Speed: commonly refer to the speed of horizontal wind, a ratio of the distance covered by the air to the time taken to cover it. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates

Wind Direction: the direction of horizontal wind expressed in degrees at which the wind originates, i.e., 0° for north or northerly wind, 90° for east or easterly wind, 180° (or -180°) degree for south or southerly wind, and 270° (or -90°) for west or westerly wind. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates

u: east-west component of the horizontal wind vector, positive value for eastward wind or west wind. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates

v: north-south component of the horizontal wind vector, positive value for northward wind or south wind . This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates.

w: vertical component of the 3-D wind vector. positive value for upward wind, This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates.

Looking comments and suggestions!

Hi everyone,

Gao, I've included my comments below. Brackets alone are comments. Bracketed italicized and bold words/phrases are my suggested edits.

Thanks all,
Ryan

Wind Speed: commonly refers to the speed of horizontal wind, a ratio of the [horizontal] distance covered by the air to the time taken to cover it [that distance]. This scalar quantity can be used to represent a value at a given location and time [instantaneous] or average over spatio-temporal extent or values as a function of spatio-temporal coordinates. [I like that you’ve included the difference between instantaneous vs averaged/down-sampled here, most users aren’t familiar with the time averaged wind measurements].

Wind Direction: the direction of horizontal wind expressed in degrees at which the wind originates, i.e., 0° for north or northerly wind, 90° for east or easterly wind, 180° (or -180°) degree for south or southerly wind, and 270° (or -90°) for west or westerly wind. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function spatio-temporal coordinates [I like that you’ve defined the coordinate system here- oceanography uses the reverse convention, so it is important that it be well defined].

u: east-west component of the horizontal wind vector, positive value for eastward wind or west wind. [This seems confusing – consider “positive value for eastward moving or west-to-east wind"]. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates.

v: north-south component of the horizontal wind vector, positive value for northward wind or south wind. [This seems confusing – consider “positive value for northward moving or south-to-north wind"]. This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates.

w: vertical component of the 3-D wind vector. positive value for upward wind, This scalar quantity can be used to represent a value at given location and time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates. [w has a meteorological definition of dz/dt; may be worth also including a definition for omega as well for completeness].

[JREyre]

@gaochen-larc
Hi Gao,
We have several comments on your proposal. They look good to me with one exception: I would include dp/dt as an option for vertical velocity, as it does not have units of distance per time.
I suggest it would be now be best if you could update your proposal based on these comments and then we could propose it for acceptance.
The remaining issue would then be what to do with the existing codes: 12005, 12006, 310, 307. Do we replace them or add to them?

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2022.12.08-TT-WIGOSMD notes:
@gaochen-larc will focus on after AGU

[JREyre]

Hi Goa,
Error in my last message - should have said "I would NOT include dp/dt ...".

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2023.01.12-TT-WIGOSMD notes:
still under discussion, moved to next FT cycle

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2023.02.16-TT-WIGOSMD notes:

Gao will update the proposal summary with details.

[joergklausen]

The principal conventionally observed quantities are

• horizontal wind direction, with dimension of degrees
• horizontal wind speed/velocity, with dimension of length per time
• vertical wind speed/velocity, with dimension of length per time
  These can be observed separately, or as vector components u, v, and w. To reflect this, I tend to recommend the following observed quantities in addition to the 3 mentioned above, even though this creates some redundancy:
• 2D wind vector, with dimension of length per time in 2D polar coordinates
• 3D wind vector, with dimension of length per time in 2D polar coordinates

[JREyre]

@gaochen-larc @joergklausen @amilan17
The Amendment above looks good.
Concerning Joerg's comment, it is important not to conflate speed and velocity, because one is a scalar and the other a vector (velocity includes speed and direction). However, the Amendment does not mention velocity, which is fine.

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2023-03-17-TT-WIGOSMD notes:
@gaochen-larc add notations to issue summary; change u, v and w to something with a little more meaning; @amilan17 will post copy of email from ET-UAM experts.

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2023.04.21-TT-WIGOSMD notes:
Gao updated the details in the proposal (above) and will update the branch.

[gaochen-larc]

Branch updated

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2023.05.04-TT-WIGOSMD/notes:
Gao will add "[zonal]" the definitions and replace the existing codes with the new content.

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2023.06.15-TT-WIGOSMD notes:

Lara reviewed the branch and noted that the issue summary is different than the branch (see comment above); there was a discussion about "north" vs "true north"; DECISION: remove units from horizontal wind direction; @gaochen-larc update branch, issue summary and create PR;

[amilan17]

Should 310 be superseded by another code? If not, then I recommend changing the status to "Retired". 

310,"\Atmosphere\Wind\Upper wind (X, Y components, horizontal)",,,"Upper wind (X, Y components, horizontal)",Horizontal component of wind as a vector in an orthogonal coordinate system.

[joergklausen]

retired=deprecated? Yes, I believe so.

[gaochen-larc]

Agree

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2023.06.30-TT-WIGOSMD notes:

validated; code 310 will be retired;

[amilan17]

Publication of these amendments is on hold pending further discussions

[amilan17]

https://github.com/wmo-im/tt-wigosmd/wiki/2024.02.15-TT-WIGOSMD notes:
moved to in disucssion;

[JREyre]

@gaochen-larc @joergklausen @amilan17
I've checked this again, and I have nothing to add, except that I don't think it necessary to specify "true north". "north" is naturally interpreted as true (geographic) north. If it were magnetic north, then this would need to be specified.

[joergklausen]

Re 12005: Given the comment further up by @mshook2012, I don't think it hurts to eliminate possible ambiguity about what 'north' is meant. Furthermore, the condition of windspeed > 0 is not reflected, either. So I would expand by saying

"The direction of horizontal wind at which the wind originates expressed in degrees, i.e., 0 deg for true north or northerly wind, 90 deg for east or easterly wind, 180 deg (or -180 deg) degree for south or southerly wind, and 270 deg (or -90 deg) for west or westerly wind. Scalar quantity to represent a value at a given location and an instantaneous time, or average over spatio-temporal extent, or values as a function of spatio-temporal coordinates. Note: wind direction is not defined for zero wind speed."

BTW (arrrgh) I initially looked at the proposal at the top to put @JohnEyre 's comments into perspective. Alas, this has not been updated in a long time. @amilan17 We need to review how to deal with changes to the initial proposal during its evolution. The only solution I see, really, is

1. Remove the "Amendment Details" from the top.
2. Paste an initial version as the first comment.
3. Paste updated versions of these Amendment Details regularly here in the comment trail, clearly labeled as "Amendment Details (working version"). This is the responsibility of the assigned member of the team (@gaochen-larc in this case).
4. Close the discussion and "freeze" the issue once a conclusion is reached, and only then add the final version at the top.

[meulenvd]

@gaochen-larc @joergklausen @amilan17 I've checked this again, and I have nothing to add, except that I don't think it necessary to specify "true north". "north" is naturally interpreted as true (geographic) north. If it were magnetic north, then this would need to be specified.

@joergklausen @amilan17 @JREyre
The use of True North came from the old Technical Regulations (WMO-No. 49, Vol I). This was to avoid confusion in the Aeronautical part were wind direction w/r Magnetic North was stated (but only for services at the aerodromes). After updates True was not used anymore, neither in the Manual to the WIGOS. In WMO-No. 8 (the GIMO), Vol I,par. 5.1.2 (units and scales), Wind direction is defined as the direction from which the wind blows, and is measured clockwise
from geographical north, namely, true north (based on WGS-84 and its EGM96). Regulatory material refer to this WMO-No. 8 if relevant. So true is used to avoid confusion with magnetic north, but in practice it is not so relevant, because the definition is clear.

Other definitions, moved from the regulatory material to GIMO, which might be relevant here are:

• “Calm” should be reported when the average wind speed is less than or equal to 0.2 m/s (< 1 kt). The direction in this case is coded as 00.
• Wind direction at stations within 1° of the North Pole or 1° of the South Pole should be measured so that the azimuth ring should be aligned with its zero coinciding with the Greenwich 0° meridian.

[gaochen-larc]

Amendment Details (working version)

Notation	Name	Description
12005	Horizontal Wind Direction	the direction of horizontal wind expressed in degrees at which the wind originates. This scalar quantity can be used to represent a value at given location and an instantaneous time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates. Note: 1) Wind direction is coded as 00 under "Calm” conditions at which the average wind speed is less than or equal to 0.2 m/s (< 1 kt). The direction in this case is coded as 00; 2) Wind direction at stations within 1° of the North Pole or 1° of the South Pole should be measured so that the azimuth ring should be aligned with its zero coinciding with the Greenwich 0° meridian.
12006	Horizontal Wind Speed	commonly refers to the speed of horizontal wind, a ratio of the horizontal distance covered by the air to the time taken to cover that distance. This scalar quantity can be used to represent a value at a given location and an instantaneous time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates.
New	u (u component of horizontal wind vector)	east-west component of the horizontal wind vector, positive value for eastward moving or west-to-east wind. This scalar quantity can be used to represent a value at given location and an instantaneous time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates.
New	v (v component of horizontal wind vector)	north-south component of the horizontal wind vector, positive value for northward moving or south-to-north wind. This scalar quantity can be used to represent a value at given location and an instantaneous time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates.
307	w (vertical component of wind vector)	vertical component of the 3-D wind vector. positive value for upward wind. This scalar quantity can be used to represent a value at given location and an instantaneous time or average over spatio-temporal extent or values as a function of spatio-temporal coordinates.

[gaochen-larc]

@meulenvd: Thank you!