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WIGOS Metadata Standard: Semantic standard and code tables
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table 1-01-05: replace Permafrost with three new variables #337

Closed amilan17 closed 2 years ago

amilan17 commented 2 years ago

Branch

https://github.com/wmo-im/wmds/tree/issue337-new

Summary and Purpose

The existing variable 'Permafrost' cannot be measured, but rather represents a state of a matrix.
The GCW Permafrost Task Team proposes to replace the variable 354 (Permafrost) by three new variables that can be measured within permafrost (Permafrost temperature, Active layer thickness and Rock glacier velocity).

Proposal

Replace variable 354 (Permafrost) by the following three new variables. Tag these with “terrestrial”, “cryosphere” and "permafrost".

Notation Name Description Tags
12014 Permafrost temperature Ground temperature measured in the permafrost terrestrial, cryosphere, permafrost.
12015 Active layer thickness Thickness of the surface layer of the ground that is subject to annual thawing and freezing in areas underlain by permafrost. terrestrial, cryosphere, permafrost
12016 Rock glacier velocity Surface velocity of a single rock glacier unit terrestrial, cryosphere, permafrost

Deprecate following entry:

Notation Name Description Path
354 Permafrost   \Terrestrial\Cryosphere\Permafrost 

Reason

“Permafrost” is currently listed as a variable, however, it is no numerical variable, which limits further usage of the observations. The proposed three variables “permafrost temperature”, “active layer thickness” and “rock glacier velocity”, on the other hand, provide numerical results, which can be used for inter-comparison, models and simulations. These variables provide refined observations on permafrost, which give a more holistic picture of specific permafrost properties.

The term 'permafrost temperature' is a state variable constrained to a specific environment. This is in line with current practice used also for atmospheric variables (224, 225, 226), ocean variables (94, 95, 405), terrestrial (388, 389, 410, 596), and space (112). This distinction appears acceptable, even though the concept of 'temperature' is the same in all of them.

Stakeholder(s)

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

GCW Permafrost Task Team:

Consultations

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

International Permafrost Association, Global Terrestrial Network for Permafrost, GCOS, PERMOS

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]

HIGH

For implementing the change in OSCAR/Surface, a migration plan is required. Before the superseded variable "Permafrost" can be remoced, it needs to be defined for each station, which of the new variables replace(s) the old variable. Since there are only 5 stations in OSCAR, which observe "Permafrost", this work can be done manually.

amilan17 commented 2 years ago

Questions to discuss:

  1. Can “permafrost” be defined as a tag on domain level as soon as it has been superseded by the 3 new variables? The variable “active layer thickness” needs to be represented in the context of permafrost, since the name is not self-explanatory.
  2. I listed under “permafrost temperature” the unit ““degrees Celsius” or “degree Celsius””, because both units are listed in table 1-02. Would you advise us to use the singular or the plural form of the unit?
joergklausen commented 2 years ago

  1. Can “permafrost” be defined as a tag on domain level as soon as it has been superseded by the 3 new variables? The variable “active layer thickness” needs to be represented in the context of permafrost, since the name is not self-explanatory. jkl: I prefer tag rather than matrix, because there can only be one matrix at the time. Permafrost is rather a property of a matrix in my understanding.

  2. I listed under “permafrost temperature” the unit ““degrees Celsius” or “degree Celsius””, because both units are listed in table 1-02. Would you advise us to use the singular or the plural form of the unit? jkl: I thought we have had a previous CR to sort this out and decide on one of the two. If that has not happened, we should decide now and deprecate the other entry. I think I prefer the plural version, ie. 'degrees Celsius'

amilan17 commented 2 years ago

@amilan17 - create branch

amilan17 commented 2 years ago

decisions:

Joerg talked about the need for outreach to the community to update their records, this should be done by Luis' team

@amilan17 check recent amendments for question on units.

@NoraCryo please add revised description to this issue as a comment for 'Active layer thickness'. Joerg recommends updating the name too. Note that this variable is part of the "terrestrial" domain.

amilan17 commented 2 years ago

@NoraCryo @joergklausen

degree Celsius no longer exists. It is superseded by degrees Celsius per #159. The codes registry will be updated soon. https://codes.wmo.int/wmdr/unit/degC

rodicanitu commented 2 years ago
  1. Proposed revised description for ACTIVE LAYER THICKESS: thickness of the surface layer of the ground that is subject to annual thawing and freezing in areas underlain by permafrost;
  2. agree to include PERMAFROST as a TAG; proposed description for Permafrost: subsurface material that remain continuously at or below 0 °C throughout at least two consecutive years (based on additional consultations with the GCW Permafrost TT concluded on 2 Nov 2021)
joergklausen commented 2 years ago

@amilan17 Please create branch. @fierz Please confirm branch once available. Also, please organize 1-2 more independent confirmations from the relevant community.

rodicanitu commented 2 years ago

@joergklausen - the permafrost submissions were developed by the group of experts listed in the submission and representing GTN-P, GCOS, Alpine and Arctic Permafrost, and facilitated by Charles. Would you recommend to invite one or more of them to comment directly on this issue in GitHub? The group is currently disseminating these terms with the respective organizations, through a semi-informal letter. Should an email confirmation be sufficient? thanks.

fierz commented 2 years ago

@joergklausen @amilan17 Confirm branch as available

fierz commented 2 years ago

@amilan17 @joergklausen

degree Celsius no longer exists. It is superseded by degrees Celsius per #159. The codes registry will be updated soon. https://codes.wmo.int/wmdr/unit/degC

Yes, I realised this and found it to be a little bit awkward to have the name of a unit in the plural form. Would you say "newtons" is the unit name for force? "degrees Celsius" will now be the exception in the codes registry that will be updated. A detail that could be solved via a typo request?

joergklausen commented 2 years ago

@joergklausen - the permafrost submissions were developed by the group of experts listed in the submission and representing GTN-P, GCOS, Alpine and Arctic Permafrost, and facilitated by Charles. Would you recommend to invite one or more of them to comment directly on this issue in GitHub? The group is currently disseminating these terms with the respective organizations, through a semi-informal letter. Should an email confirmation be sufficient? thanks.

@rodicanitu A confirmation here in GitHub is what we should have. Thanks

rodicanitu commented 2 years ago

Correspondence from Anna Irrgang (Global Terrestrial Network for Permafrost - GTN-P) on 8 Nov 2021:

confirm that the most recent description you suggested for the active layer thickness works well for me. GCW Letter to the Permafrost Community shared with the Permafrost Carbon Meeting on Nov. 16-18th. if there will come any input/comments from the permafrost community than it might come after November 18th. Actually coming back to the definitions I would like to inform you that the 0 deg C definition for permafrost will be (still) applied in the new GTN-P Strategy and Implementation Plan (SIP). The SIP will be released next week during the GTN-P National and Young National Correspondents meeting. We cannot hold the SIP back any longer (it is meant to be for 2021-2024!), so this definition will continue to be applied for the GTN-P. 18.11.2021 update (R Nitu): confirmation deferred to 26 Nov.

amilan17 commented 2 years ago

Meeting #16 notes:

meulenvd commented 2 years ago

@amilan17 @joergklausen

degree Celsius no longer exists. It is superseded by degrees Celsius per #159. The codes registry will be updated soon. https://codes.wmo.int/wmdr/unit/degC

Yes, I realised this and found it to be a little bit awkward to have the name of a unit in the plural form. Would you say "newtons" is the unit name for force? "degrees Celsius" will now be the exception in the codes registry that will be updated. A detail that could be solved via a typo request?

The basic reference for the naming convention associated to SI is the SI brochure, authorized by the int. sci. associations (currently, version 9), to be found on the official BIPM website for SI, https://www.bipm.org/en/publications/si-brochure. In this document it is clearly stated that: "one must neither use the plural nor mix unit symbols and unit names within one expression" (par 5.2). For the Celsius temperature (the thermodynamic temperature is also called kelvin temperature) the unit is defined as follows (par. 2.3.1 and table 4): "The unit of Celsius temperature is the degree Celsius, symbol °C, which is by definition equal in magnitude to the unit kelvin. A difference or interval of temperature may be expressed in kelvin or in degrees Celsius" So the unit is not degrees Celsius, but degree Celsius (not plural). But when you express values then the word degree as such has to be expressed with an 's', so 20 degrees Celsius. If, like with the kelvin temperatuur, you refer to the defined unit you will express values as 20 kelvin (not plural, and with lower case). Degree Celsius / degrees celsius is still a kind of a black sheep within the SI units vocabulary, largely because the (derived) Celsius temperature is still more popular than the (basic) thermodynamic temperature (with base unit K).

joergklausen commented 2 years ago

@meulenvd Thanks, I was not aware of this guidance on the use or not of plural. I believe we have other cases like that in the unit code table. It’s not very urgent to fix this, as the meanings won’t change and the notations won’t be affected.
~@amilan17~ Could you open an issue to review and fix this, please? Target FT2022-1 if possible, otherwise the next one.

rodicanitu commented 2 years ago

@joergklausen @amilan17 Confirm that we have no additional feedback from the relevant communities (International Permafrost Association, Global Terrestrial Network for Permafrost, GCOS, PERMOS).

Therefore, the variable names and associated descriptions are ready for approval.

NOTE; the submission includes the tag Permafrost and its description: subsurface material that remain continuously at or below 0 °C throughout at least two consecutive years

amilan17 commented 2 years ago

@joergklausen - I'm unclear on where we are keeping tags. Is it the matrix table? https://github.com/wmo-im/wmds/issues/278

joergklausen commented 2 years ago

@joergklausen - I'm unclear on where we are keeping tags. Is it the matrix table? #278

Yes, I have updated the table in the issue, but I fail to find a corresponding table 1-06-02 in the branch ... has it not been created yet? Also, 1-06 should become 1-06-01, isn't it?

rodicanitu commented 2 years ago

@amilan17 @joergklausen Thank you on behalf of the GCW Task Team on Permafrost

amilan17 commented 1 year ago

@fstuerzl -- Do you have an ETA for when these variables will be included in OSCAR/Surface?

fstuerzl commented 1 year ago

@amilan17, we can include it, as soon as the migration of the existing permafrost observations in OSCAR is defined and the NFPs are informed about the change. @rodicanitu, the variable is only used at 5 GCW CryoNet stations. Should the variable "Permafrost" at these stations be replaced by all three new variables?