Merge pull request #40 from mjg41/adr-004-odedt-model-keyword

ADR-005: Introducing model keyword for DestinE DE330 On-Demand Extremes DT.

Author: tlmquintino

ADR/ADR-005-ODEDT-model-keyword.md

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+# ADR-005: Model keyword for DE330 (ODEDT)
+
+# Status
+
+Proposed
+
+# Last Updated
+
+10.03.2026
+
+# Context
+
+### Background
+
+The on-demand-extremes-dt routinely runs multiple models covering the same period, such as different NWP models (ALARO, AROME, HARMONIE-AROME) as well as several impact models (AQ, Hydrology, renewables, wildfire etc.).
+
+Thus, an additional axis is needed to cope with several models running with all other mars metadata identical. To this end we would introduce the model keyword to the on-demand-extremes-dt data index, as has been introduced in other datasets and contexts such as class=ai. We would add the model keyword in the same way here. Thus this represents a consistent approach in-line with other datasets.
+
+Values in ecCodes are currently as follows, but would be extended as the impact models become known and well formed ( `localConcepts/destine/modelNameConcept` ):
+
+- IFS
+- AIFS
+- ICON
+- ALARO
+- AROME
+- HARMONIE-AROME
+- \<air-quality-impact-model\> (to be updated with value from DE330)
+- \<hydrology-impact-model\> (to be updated with value from DE330)
+- \<wildfire-impact-model\> (to be updated with value from DE330)
+- …
+
+### MARS archiving approach
+
+MARS namespace:
+
+<pre><code>{
+  "messages": [
+    {
+      "date": 20260211,
+      "time": 1200,
+      "expver": "0001",
+      "class": "d1",
+      "dataset": "on-demand-extremes-dt",
+      "georef": "u23er4",
+      "type": "fc",
+      "stream": "oper",
+      "step": 6,
+      "levtype": "sfc",
+      <strong>"model": "HARMONIE-AROME",</strong>
+      "timespan": "none",
+      "param": 167
+    }
+  ]
+}
+</code></pre>
+
+# Options Considered
+
+### 1. Include model key
+
+We believe this key is necessary to index data coming from different models within the on-demand Extremes DT project.
+
+# Analysis
+
+- Prototype at: [text](https://github.com/ecmwf/eccodes/tree/feature/ECC-2222-model-for-de330)
+- This has been introduced in other datasets such as class=ai. We would add the model keyword in the same way here. Thus this represents a consistent approach in-line with other datasets.
+
+# Decision
+
+Meeting was held on 06/03/2026 to discuss the proposal with:
+
+- Simon Smart
+- Emanuele Danovaro
+- Seb Villaume
+- Robert Osinski
+- Bojan Kasic
+
+Following up meeting to confirm with User Services with:
+
+- Paul Dando
+- Bojan Kasic
+
+Everyone was happy with the proposal. We will proceed with the implementation.
+
+# Consequences
+
+- ecCodes development to add model keyword to indexing namespace for on-demand-extremes-dt data
+- metkit development to add new values of model keyword to language file.
+
+# References
+
+# Authors
+
+- Matthew Griffith
+- Sebastien Villaume
+- Robert Osinski