New HARMONIE Cycle 43 now available
The moment many of you have been waiting for has finally arrived: the launch of the first products of the long-awaited HARMONIE Cycle 43 on the KNMI Data Platform! With this new cycle, you do not only have technical improvements, but also changes that will affect your analyses and forecasts.
Technical improvements
With the transition to the new HARMONIE Cycle 43, accompanied by a move to a new supercomputer in Iceland, significant technical improvements have been made. For example, there are a number of technical and content differences from the current HARMONIE Cycle 40 that give the model different meteorological characteristics.
The changes are:
- Improved horizontal resolution from 2.5 to 2.0 km grid points
- More vertical layers, from 65 to 90 layers, with the bottom one going from 12 to 5 meters in height
- The model domain has been significantly expanded
- Run frequencies increased to hourly runs with 60 hours of forecast
- 5 ensemble members per hour with a 60-hour forecast for each ensemble member
- Use of a Single Precision version of the forecast model
- Use of the T2m and RH2m in the data assimilation for the atmosphere
- Using ECMWF EPS members as an edge for the UWC West ensemble (see Figure)
- The use of Stochastic Parameter Perturbation (SPP) as a method to generate dispersion in the ensemble members in the model itself
An important technical change is the increased resolution of the cutaway around the Netherlands. The number of points goes from 300x300 to 390x390, and the resolution improves from 2.5 to 2.0 km. In contrast, the second cutaway, which covers almost the entire UWC West area, has no increased resolution compared to the current Western Europe area. However, the total number of points increases for both packages, resulting in larger file sizes.
Meteorological improvements
These technical improvements affect not only the accuracy of the data, but also the meteorological modeling itself. For example, there is an improved representation of fog and low clouds, as well as adjustments to turbulence diagrams and microphysical processes. An updated land use map contributes to a more realistic representation of vegetation distributions and the annual course of roughness. We recommend reading the full article by Sander Tijm in Meteorologica (March 2024) for an in-depth analysis of the effects of this new HARMONIE Cycle 43 on your operations.
How to continue...
We published this dataset as soon as possible. It is possible that occasionally a file may still be missing because it is not yet 100% stable. This is being worked on to get this as stable as possible.
Currently, only product 1 is posted on KDP along with the reforecast of this product, these are the deterministic runs of Harmonie for the Dutch area. The ensemble runs of Cy43 are not yet operationally available. We aim to put the other products live as soon as they are ready. These are products P2, P3, P4, P5, BES and the reforecasts. Due to the shutdown of our own HPC and the delays we have faced, the process has begun to continue to run HARMONIE Cy40 shadow alongside Cy43. At this time, no decision has been made on how long this dual phase will last. The end of the dual phase will be determined in consultation with the customers
Links to datasets
Product 1: https://dataplatform.knmi.nl/dataset/harmonie-arome-cy43-p1-1-0
Reforecast from October 2020 till September 2023: https://dataplatform.knmi.nl/dataset/harmonie-arome-cy43-p1-reforecast-1-0
