There is a lot to say about 2017, and the following pages allow us to remember or discover some of the key moments. Possibly the most striking aspect that comes to mind is the way our past, present and future collided in that specific year.

2017 was a firework of anniversaries. It marked 20 years of 4D-Var at ECMWF, and of seasonal forecasts, and 25 years of ensemble prediction and wave forecasting. It was also the year when ECMWF’s Council approved the development of our future data centre in Bologna, Italy, and voted a budget allowing a substantial increase in our computing capability. The end of the year saw the Government of the UK, our host nation, formally offering to relocate ECMWF’s headquarters to accommodate our requirements.

A common denominator between all those events is that they illustrate the relationship based on trust which connects ECMWF and its Member States. The science behind ensemble prediction or 4D-Var was not born in one day. It took years and years before it even looked like something which could be adequately demonstrated. Developing a state-of-the-art data centre is also a substantial investment in the future. These are strong statements of support from the Member States.

Trust is earned, and 2017 has allowed us to pay our dues and serve our Member States and other users with some noticeable progress towards our Strategy to 2025. Some good examples include the work undertaken to assess the best ensemble configurations to make a 5 km ensemble affordable; the more efficient radiation scheme, completely recoded to be more flexible and delivering efficiency gains up to 30-35%; the release of the new seasonal system, SEAS5, notably improving El Niño prediction.

Our partnership with the European Union is also thriving and delivering results that cut across the whole of ECMWF. The new climatology derived from aerosol data developed by the EU-funded Copernicus Atmosphere Monitoring Service that we operate on behalf of the EU is contributing to improving our forecasts. The latest version of our reanalysis, ERA5, produced by our Copernicus Climate Change Service now provides a useful benchmark and reference for identifying interannual variations in predictability; last but not least, this strong partnership with the EU is reinforced by the work they have selected us to deliver on fire prediction and human carbon emissions.

probabilistic skill
Probabilistic skill ECMWF’s duty to Member States is to continue improving medium-range forecast skill. Results for the northern hemisphere extratropics show that the skill of the ensemble forecast in predicting 24-hour precipitation totals continues to increase. The computation of skill is based on the continuous ranked probability skill score (CRPSS). The chart shows 12-month running average values of the forecast range at which the CRPSS drops below 0.1.

Our work with the WMO continued to flourish in 2017, with Nguyen Thanh Tung from Vietnam finishing his fellowship in September after 12 months of mutually beneficial exchanges. This year the WMO designated ECMWF as a World Meteorological Centre and endorsed us as the Lead Centre for Wave Forecast Verification.

ECMWF is above all a scientific organisation, so the arrival of Dr Andy Brown as Director of Research is also a milestone of 2017. Andy joined us one year into the implementation of the Strategy to 2025, with sizeable challenges to address … and an impressive scientific team to support him.

Science in numerical weather prediction could not function any more without the support of computing sciences and technology, so Council’s approval of our next HPC budget at its December session was a great outcome. Six months after approving the building of our new state-of-the-art data centre in Bologna, Council confirmed its confidence in our teams by endorsing our request for a substantial increase in computing capability. As we continue to push our science towards the goals of our Strategy to 2025, there could not have been a better way to end 2017.

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