1-02: Align plurality of units with SI conventions
Closed this issue · 15 comments
Summary and Purpose
Branch
https://github.com/wmo-im/wmds/blob/issue361/tables_en/1-02.csv
Stakeholders
Proposal
Remove the "s" from unit name.
| degC | degree Celsius (°C) | SI derived unit of temperature, SI base unit equivalent: K |
Reason
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).
Originally posted by @meulenvd in #337 (comment)
Expected Impact of Change
LOW
Other units to consider
| degrees Celsius per 100 metres | degC.hm-1 | Unit of spatial gradient of temperature per 100 metres |
| degrees Celsius per metre | degC.m-1 | Unit of spatial gradient of temperature per metre |
| square metres | m2 | SI derived unit of area |
| cubic metres | m3 | SI derived unit of volume |
Thank you @meulenvd!
There are many cases that the plural was used. We need to go through the entire list systematically. Also, We will need to make changes or replace the names with plural from the original unit code list. Should we proceed? @amilan17 @joergklausen
For reference and history: WMDR initially used the table https://codes.wmo.int/common/_unit as a baseline. You will see there are already a number of plurals in that list. We didn't pay much attention to that aspect at the time. My suggestion to evolve that list and refer to it or the purpose of WMD was not taken up. So, we now have our own code list on units ... with the liberty to at least align it better to SI conventions.
@gaochen-larc Please proceed and remove all plural forms, also all references to SI where those are not appropriate.
@meulenvd (former WMO/CIMO) and @semmerson (US/NIST) Please help us and confirm the branch once ready.
@gaochen-larc @joergklausen @fstuerzl is this ready for FT?
Line 69: space missing
Line 157: for consistency, 1E-3 should be 0.001
Except for these non-material changes I spotted, this is ready for FT.
Line 69: space missing Line 157: for consistency, 1E-3 should be 0.001 Except for these non-material changes I spotted, this is ready for FT.
Branch is updated: 8e463e9
One last question, should we use "a" for year or "yr" for year? I vaguely recall someone raised this issue before. Other than this, it is ready for FT.
One last question, should we use "a" for year or "yr" for year? I vaguely recall someone raised this issue before. Other than this, it is ready for FT.
This question is unrelated to the plurality in definitions.
@joergklausen @gaochen-larc Is this ready for FT?
Please review tables_en/1-02.csv in the diff (https://github.com/wmo-im/wmds/pull/378/files) of the PR.
I think it is. Can @meulenvd also go through this one last time?
We need to review the feedback recieved from Charles Fierz and determine fix for FT22-1 or defer to FT22-2.
@amilan17 Please see my e-mail to you from 15 March (RE: Amendment proposals for WIGOS Metadata Codes (respond by 4-March-2022)). Attached to it, I had sent my comments and corrections. I don't find those in any way reflected in the pdf you have linked above. Is this an oversight or a conscious decision?
@amilan17 @gaochen-larc @joergklausen
Thanks to all of you for considering and going through my comments.
- I fully support the use of derived SI unit and dropping 'prefixed'
- Fully agree SI does not recommend numerical values. My comment on, for example week, was on the way large numbers are written, that is 604 800 and not 604800. This is a SI recommendation but would require quite a few changes in the table that are not worth going through.
- Regarding kilocalory per square centimetre, I could not find it in either https://codes.wmo.int/common/_unit or https://codes.wmo.int/wmdr/unit. I think it was proposed by Dr Bianchi last year, thus there would be no need to deprecate it.