Harmonie UWC West
In this article we would like to inform you about the recent developments regarding the realization of a new HARMONIE, our short-term weather forecast model. In addition, through this article, we are making available a test set of the new model to ensure a smooth transition. The new HARMONIE will be run on a new supercomputer for the partners of the UWC West consortium, including Denmark, Iceland, Ireland and the Netherlands. The main goal of this joint initiative is to improve short-term weather forecasts while keeping operational costs at a similar level. Currently, weather forecasts at De Bilt are generated by an on-site High-Performance Computer (HPC). Starting in 2024, these forecasts will be generated in cooperation with other meteorological institutes, using a new HPC in Iceland. This shift includes not only a change in the source of the forecasts, but also in their resolution and frequency.
Technical improvements:
- The model used is Harmony Cy43
- The resolution is increased from 2.5 km2 to 2 km2 grid points
- The number of layers goes from 65 to 90 for more accurate forecasts
- The ensemble consists of 15 members, with 5 deterministic runs every hour
- The forecast will be expanded from 48 hours to 54 or 60 hours, depending on available computing power and the wishes of UWC West
- The model will carve out the NL domain from the UWC West domain
What remains:
- Harmony data will remain in GRIB 1 format
- Packages remain present with the same cutouts
- Packages 2 and 4 were split because it could save in licensing costs for the buyer. Now that that no longer matters, it may be that these will be merged again. Only upon publication will this be certain.
Timeline
Gereed The launch of the new HARMONIE Cy43 is scheduled for the end of February. In all likelihood, the old HARMONIE Cy40 will be evicted in early April. To ensure a smooth transition, we have test sets ready for package 1 and package 3. The cutout of package 1 corresponds to package 2a/b, and the cutout of package 3 corresponds to packages 4a/b and 5. To test beforehand, copy the link for the test set: https://filesender.surf.nl/?s=download&token=df6c9f10-8980-4e4e-bde3-9ed6dab66f29. This test set is valid until 26 February 2024, with the prospect that a full test flow will have been initiated by then. The test set is large, over 1 GB, and contains both package 1 (starting with HA43_N20) and package 3 (starting with HA43_N55). These file sizes are representative of the new data streams.
We hope to keep the file names similar with only a version change, from harm40_* to harm43_*. This will only become certain once the datasets are published.
In a future newsletter, we will give more attention to what to expect from the new HARMONIE and will update you on the meteorological differences between the old and new weather forecasts. For any questions, please foreward them to opendata@knmi.nl.