Wmo paramids#62
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oiffrig
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May 15, 2026
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Pull request overview
Adds a new MARS language decision record describing how to handle short-name ambiguity for new WMO-unit paramids (including an explicit units= post-processing keyword concept), and updates the MARS language ADR index/statuses accordingly.
Changes:
- Mark MARS-007 as Accepted in both the index and the decision record status line.
- Add new decision record MARS-008 (“WMO Units”) proposing an approach for short-name handling and on-the-fly unit coercion.
- Add MARS-008 to the MARS language README index.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.
| File | Description |
|---|---|
| MARS language/README.md | Updates the ADR index to reflect MARS-007 acceptance and add MARS-008. |
| MARS language/MARS-007-Timespan-Absence.md | Updates the ADR status line to Accepted. |
| MARS language/MARS-008-WMO-Units.md | Introduces a new ADR proposing handling/UX for WMO-unit paramid transitions and a units= concept. |
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dsarmany
approved these changes
May 21, 2026
sebvi
reviewed
May 27, 2026
| This approach is the simplest/most natural approach. It maintains the contextually unique mapping of short names to `paramid`s in the MARS language expansion, and as a result ensures that the old/new behaviour of the language will be the same for requests using short names as for `paramid`s. | ||
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| The biggest issue with this approach is that we already have data produced in production systems (DE/AI) which use the ambiguous short names. A remapping to change this would result in systems that either need to hard code the date to support this old data, to rearchive this old data after processing, or would break access to it. Further, it would require changing user requests for unchanged data queries. | ||
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In addition, renaming the post-migration short names for base parameters would force corresponding renames for many related parameters that are generated by design from the same short-name root. Statistical variants follow a structured naming pattern (for example tp as the base, avg_tp for averages, min_tp for minima, and max_tp for maxima), so changing one base short name propagates into a wide family of derived short names.
rdosinski
reviewed
May 27, 2026
| #### 1. Unique Short Name Mapping | ||
| This approach is the simplest/most natural approach. It maintains the contextually unique mapping of short names to `paramid`s in the MARS language expansion, and as a result ensures that the old/new behaviour of the language will be the same for requests using short names as for `paramid`s. | ||
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| The biggest issue with this approach is that we already have data produced in production systems (DE/AI) which use the ambiguous short names. A remapping to change this would result in systems that either need to hard code the date to support this old data, to rearchive this old data after processing, or would break access to it. Further, it would require changing user requests for unchanged data queries. |
Contributor
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Why would a rearchival be necessary ? The data are indexed with the paramId. The shortName is not used to index.
sebvi
reviewed
Jun 26, 2026
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| The technically straightforward solution here is to enforce that each new `paramid` is assigned a new short name - which will require inventing a new set of short names (an annoying process, as in many cases the obvious ones are already in use for the existing data). | ||
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| Some of the new `paramid`s are not new - see those belonging to table 228 - but have not previously been used for operational data. They have, however, been used for existing data within Destination Earth and for AI models. For these uses they have used short names which are the same as for the old `paramid`s (an example of this is `tp` which maps to both 228 and 228228). At this point it has not caused any problem mapping short names to `paramid` values as it can be disambiguated by context (e.g. `class=od` vs `class=ai`). |
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some of the not new paramIds were also likely used in OpenData on top of DestinE and AI.
Co-authored-by: Olivier Iffrig-Petit <olivier@iffrig.eu>
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