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Topic / title | Description | Related activities / comments |
|---|---|---|
General issues | ||
| G1. Artefacts at long lead times | Beyond 10 days, unphysical artefacts can emerge in the model, particularly under areas of high elevation. These are particularly visible for mean sea level pressure and temperature at 1000hPa.
1000hPa temperature artefact beneath the surface of the Andes at 360hours into the forecast. | Investigations are underway to understand and fix this issue in future cycles. |
| G2. Over-dispersion | On average, ensemble standard deviation is larger than RMSE of ensemble mean for a range of variables
Spread and error evolution for 850hPa temperature showing over-dispersion between days 2 and 8. | IFS-ENS and AIFS-CRPS share the same initial condition perturbation amplitude. Re-scaling is under investigation. |
Precipitation | ||
| P1. Very small values in dry regions | Very small values (e.g. <0.1mm/6h) of precipitation can unphysically occur in very dry regions, which are particularly noticeable when looking at long accumulation periods.
240h accumulated precipitation | Investigations are underway to understand and fix this issue in future cycles. |
2m temperature | ||
Clouds | ||
| C1. Reduced spatial resolution in cloud fields | Cloud In general, AIFS ENS significantly improves on the representation of small scale features compared with AIFS Single. However cloud fields display features at a lower spatial resolution than many of the other fields predicted by the AIFS ENS. Features have a resolution closer to the 1-degree resolution of the model processor grid.
Example of reduced spatial resolution for cloud fields over Europe.
Energy spectra for total cloud cover at day 1, showing reduced energy at small scales compared with the IFS analysis. | Investigations are underway to understand and fix this issue in future cycles. |
