Annual Report 2023
Foreword

Increased horizontal resolution for ensemble forecasts and many other enhancements in both the model and data assimilation led to much-improved skill scores in 2023, and we launched the first version of our ML weather forecasting model – the AIFS.

Florence Rabier, Director-General

Florence Rabier, Director-General

2023 will very likely be remembered as the year when machine learning (ML) stormed the world of meteorology. Whilst many organisations such as ours had been experimenting with ML for a few years, including replacing or adding some ML components in our conventional forecasting systems, the fast-paced move into ML by some big corporations shook us into boldness. As a result, 2023 saw the birth of our ML weather forecasting model – the AIFS (Artificial Intelligence Forecasting System), as well as the start of an ambitious pilot project with our Member States.

We did not rest on our laurels when it came to the Integrated Forecasting System (IFS) though. The cycle upgrade implemented in June, Cycle 48r1, saw the ensemble forecast horizontal resolution increase to 9 km, taking it to our highest resolution.

Many other enhancements came to fruition with this upgrade in both the forecast model and data assimilation, leading to much-improved skill scores.

Substantial changes were also made to extended-range forecasts, which now run daily instead of twice weekly and have 101 ensemble members instead of 51.

The European Weather Cloud, developed and run in partnership with EUMETSAT, became operational in 2023. It widens the offering of data and services from both organisations to our Member States, but also to the broader meteorological community.

Our collaboration with the European Union remained strong and effective during the period. The EU-funded Copernicus Climate Change Service (C3S) that we implement found that the global-mean surface air temperature was more than 1.5°C above pre-industrial levels in early June, which was a first for a summer month. Over the whole year, it was at its highest level yet, close to 1.5°C above pre-industrial levels.

The ECMWF-coordinated project to monitor anthropogenic CO2 emissions worldwide completed its final year, feeding into the much-awaited permanent anthropogenic greenhouse gas emissions Monitoring and Verification Support Capacity (CO2MVS), which is being developed as part of the EU’s Copernicus Atmosphere Monitoring Service (CAMS), implemented by ECMWF. Last but not least, the EU’s Destination Earth initiative, which we are developing jointly with ESA and EUMETSAT, was signed off for its second phase at the end of 2023.

A lot more happened over the year thanks to the talent and extremely hard work of our staff and the strength of partnerships with the national meteorological services of our Member States and beyond. Their dedication and support are what make ECMWF, and what made 2023 yet another fantastic year to be ECMWF.

June 2024

The primary headline score we use to evaluate long-term ensemble forecast performance shows the lead time at which the continuous ranked probability skill score (CRPSS) for 850 hPa temperature drops below 25% for the extratropical northern hemisphere. Red lines show 12-month running mean values, blue curves show 3-month running mean values.

Medium-range ensemble forecast skill

The primary headline score we use to evaluate long-term ensemble forecast performance shows the lead time at which the continuous ranked probability skill score (CRPSS) for 850 hPa temperature drops below 25% for the extratropical northern hemisphere. Red lines show 12-month running mean values, blue curves show 3-month running mean values.