Impact

Our research, collaborations, and product developments improve the quality, usefulness and accessibility of ECMWF products and services for Member and Co-operating States and the broader meteorological community.

Understanding the operational requirements of our users is key to improving forecasting systems and forecast quality.

The quality of our forecasts was consistently high in 2023, and the forecasting system upgrade to IFS Cycle 48r1 in June led to much-improved skill scores. In addition to the new products introduced with the upgrade (described earlier in the report), other products were developed to help the prediction of extremes following feedback from Member States. These included updated parameters for the detection of convection-related high-impact weather, and new visibility meteograms developed with the Hungarian and Dutch meteorological services with display options tailored for aviation forecasting and public warnings.

Open data, coupled with development of open-source tools to facilitate the use of data, are fundamental to increasing the impact of our products; 200,000 graphical products were served on average every day through our open charts, while numerical data were available from our open data portal, Microsoft platforms and Amazon Web Services.

Understanding the operational requirements of our users is key to improving forecasting systems and forecast quality.

The EU Copernicus services we run supported scientists and policy- and decision-makers with consistent, quality environmental information. The Copernicus Atmosphere Monitoring Service (CAMS) monitored the ozone hole and the effects of various events on the atmosphere and released a back extension for the CAMS atmospheric composition reanalysis.

The Copernicus Climate Change Service (C3S) published updates on the evolving state of the climate as well as seasonal forecasts and its flagship European State of the Climate report. New data included a gridded monthly climate projection dataset and a back extension for ERA5. Through the Copernicus Emergency Management Service (CEMS), we contributed to major upgrades of the European and Global Flood Awareness Systems.

Understanding the operational requirements of our users is key to improving forecasting systems and forecast quality. Visits to national meteorological and hydrological services in eight of our Member and Co-operating States were opportunities for us to listen to their experiences and discuss the evolution of products and services. Annual forums for computing representatives and meteorological users, and a new forum for users from Co-operating States, were further occasions to hear from our members.

Workshops – in person, virtual and hybrid, training courses, and a Massive Open Online Course (MOOC) on machine learning for weather and climate facilitated knowledgesharing on a wide range of topics. These were complemented by participation at international events such as COP28, where we joined partners to highlight support for WMO programmes and demonstrate the use of Copernicus data and services.

ECMWF forecasts help users prepare early warnings of severe weather, such as the extreme heat experienced in Europe in summer 2023.

Extreme heat

ECMWF forecasts help users prepare early warnings of severe weather, such as the extreme heat experienced in Europe in summer 2023.

© Philippe Clement/iStock/Getty Images Plus
Forecast performance

We use a comprehensive range of verification statistics to regularly evaluate and compare the accuracy of our forecasts.

The upgrade to Cycle 48r1 of the IFS in June included new physics and an increased horizontal resolution of medium-range ensemble forecasts (ENS) from 18 to 9 km. This brought further improvements in upperair forecast skill, with the ENS headline score for June–August 2023 showing the highest skill ever when compared to previous summer seasons, and the 12-month running average of the score reaching its highest value so far. The resolution increase also improved ENS tropical cyclone track and intensity forecasts.

In the medium range – which is ECMWF’s primary priority – compared to other global forecast centres, we maintained the lead for upper-air parameters. For surface parameters, in particular 2 m temperature and 10 m wind speed, some other centres took the lead in the short range.

However, the number of large ENS errors for 2 m temperature and 10 m wind speed has further decreased. For ocean wave parameters, we maintained the lead over other global centres for both peak period and significant wave height.

An increase in ensemble size from 51 to 101 for extended-range forecasts led to improvements in forecast performance across all parameters over the forecast range from week one to week four. The change in forecast frequency from twice a week to daily provides additional lead time for major events and transitions in weeks two to four.

Our seasonal forecast gave very good predictions of the transition early in 2023 from La Niña to El Niño conditions, even on the long-range (one year) timescale. The exceptionally warm northern hemisphere autumn 2023 season was well captured, while the cold anomaly in northern Europe was missed.

The number of large 2 m temperature errors in ensemble forecasts reached an all-time minimum in 2023. The chart shows the proportion (%) of forecasts with such errors (defined as having a Continuous Ranked Probability Score (CRPS) exceeding 5 Kelvin) at day 5 in the extratropics. Shown are 3-monthly values (blue) and a 12-month running average (red). Verification is against SYNOP observations.

Ensemble forecast headline score improvements

The number of large 2 m temperature errors in ensemble forecasts reached an all-time minimum in 2023. The chart shows the proportion (%) of forecasts with such errors (defined as having a Continuous Ranked Probability Score (CRPS) exceeding 5 Kelvin) at day 5 in the extratropics. Shown are 3-monthly values (blue) and a 12-month running average (red). Verification is against SYNOP observations.

Heatwave over southwest Europe

During July and August, Europe experienced two major heatwaves in the south, while northern Europe saw a lot of rain with flooding in Norway and Sweden. The July heatwave affected countries around the Mediterranean Sea, with major wildfires, especially in Greece, while the August heatwave affected southwestern Europe in Spain, France, and Switzerland.

Globally, the average surface air temperature of 16.77°C over the northern hemisphere summer season (June–July–August) 2023 was by far the warmest in the ERA5 record. July and August 2023 were the two warmest months on record and were estimated to have been around 1.5°C warmer than pre-industrial levels, based on the 1850–1900 reference period.

During this heatwave, the city of Lyon in France saw 17 days in a row with temperatures above 30°C (9–25 August), which peaked at 41.4°C on 24 August. In Spain, Bilbao on the north coast set a record of 44.0°C on 23 August.

In general, the predictability of the August heatwave over southwestern Europe was good. For southeastern France, extendedrange predictions showed that 30 days before the peak of the August heatwave, the ensemble mean was slightly above the model climate mean. About 20 days before the peak, the ensemble mean became progressively warmer than the model climate mean, crossing the 99th percentile six days before the peak of the event.

In the medium-range forecasts, the Extreme Forecast Index indicated extreme values (0.8 and above) for maximum temperatures on 23 August over southeastern France and Switzerland from 17 August. However, errors in predicting the winds along the Atlantic coast of Spain and France meant medium-range predictions missed the extreme surface temperature in those locations, despite a good signal in 850 hPa temperature.

Forecast evolution plot for 3-day (22–24 August 2023) 2-metre temperature over southeastern France.

Forecast evolution

Forecast evolution plot for 3-day (22–24 August 2023) 2-metre temperature over southeastern France.

Storm Daniel

In early September 2023, a set of extreme rainstorms led to devastating flooding in parts of Greece, Bulgaria and Türkiye. These events related to development of a surface cyclone nearby on the night of 4 September, assigned the name ‘Daniel’.

For rainfall associated with Storm Daniel over Greece and the Mediterranean from 4 to 8 September, the signal for an extreme event appeared in the ECMWF ensemble (ENS) 3 to 4 days in advance, between 30 August and 1 September.

In subsequent days, Daniel meandered slowly across the Mediterranean before adopting an east-south-eastward trajectory near northern Libya late on 8 September, whereupon it became a medicane. Landfall was near Benghazi around 23 UTC on 9 September.

The resulting intense rainfall over the mountains of northern Libya on the night of 10/11 September led to two dams bursting, and there were 5,000–15,000 fatalities as buildings were swept away. This was likely the deadliest rainfall-related flooding disaster since ECMWF started producing operational forecasts in the late 1970s, and the second most deadly dam-related disaster of all time. While the ECMWF ensemble indicated the risk of the extreme rainfall roughly a week in advance, the magnitude was likely underestimated in the forecasts.

Extreme Forecast Index (EFI, shading and red contours) and Shift Of Tails (SOT, grey and black contours; 0, 1, 2, 5) for 5-day accumulated rainfall on 4–8 September 2023, from operational forecasts with a start time of 00 UTC on 1 September 2023.

Extreme Forecast Index for rainfall

Extreme Forecast Index (EFI, shading and red contours) and Shift Of Tails (SOT, grey and black contours; 0, 1, 2, 5) for 5-day accumulated rainfall on 4–8 September 2023, from operational forecasts with a start time of 00 UTC on 1 September 2023.

Transport of Saharan dust across Europe

Atmospheric dust can lead to adverse health effects and impact solar energy generation. For the first major transport of Saharan dust across Europe in 2023, CAMS forecasts showed high values of aerosol optical depth and dust concentrations across the Iberian Peninsula on 20 February, with forecasts from 21 February showing transport across France and further north between 21 and 23 February, reaching as far north as Denmark. The forecasts also showed high PM10 concentrations (particulate matter where particles are less than 10 micrometres in diameter) at the surface for Spain, and at higher elevations, for example in the Pyrenees and the Alps.

The dust transport followed a similar, if less pronounced, episode the week before. On 13 February, the Calima wind carried Saharan dust to the Canary Islands. On 14 and 15 February, the dust transport continued northwards as far as Ireland and the UK.

Evaluation of the CAMS forecasts against independent measurements from the Aerosol Robotic Network (AERONET) showed good agreement in the timing and magnitude of the aerosol optical depth evaluations at several sites in Spain and Portugal in February.

Daily maximum total aerosol optical depth (AOD) at 550 nm initialised on 15 February 2023 at 00 UTC and valid for 15 February. Source: Copernicus Atmosphere Monitoring Service.

Saharan dust transport

Daily maximum total aerosol optical depth (AOD) at 550 nm initialised on 15 February 2023 at 00 UTC and valid for 15 February. Source: Copernicus Atmosphere Monitoring Service.

EFAS and GloFAS kilometrescale forecasting

For the Copernicus Emergency Management Service (CEMS), we work with the Joint Research Centre (JRC) of the European Commission. In 2023, as part of our activities as CEMS hydrological forecast computation centre, together with the other CEMS centres and the JRC, we implemented operationally kilometre-scale hydrological forecast systems for both the European and Global Flood Awareness Systems (EFAS and GloFAS). This increased the spatial resolution of EFAS 12-fold (to ~1.4 km grid size), and that of GloFAS by a factor of 4 (to ~5 km). GloFAS version 4 was released in July 2023, and EFAS version 5 in September 2023.

The changes in the modelling set-up also included an update in the physical property maps used in the hydrological model and new model parameters, thanks to a complete recalibration of both EFAS and GloFAS models (for GloFAS undertaken by the JRC).

The increase in spatial resolution allowed us to increase the number of calibration points, for EFAS considering river basins from 150 km2 , and a much better representation of the river network, with more reporting points being highlighted during a flood event.

EFAS mapviewer showing the increase in spatial resolution when looking at rivers (coloured segments), with EFAS v5 (right) better representing small rivers than EFAS v4 (left). The plots show EFAS reporting points for 17 October 2023 (12 UTC) over southern France.

EFAS reporting points for flood events

EFAS mapviewer showing the increase in spatial resolution when looking at rivers (coloured segments), with EFAS v5 (right) better representing small rivers than EFAS v4 (left). The plots show EFAS reporting points for 17 October 2023 (12 UTC) over southern France.

ERA5 data extended to 1940

ERA5 has well over 125,000 users, ranging from researchers to professional consultants, big data experts, journalists, policy-makers and the public.

A significant new segment of ERA5 reanalysis data for 1940 to 1958 was made available, helping build a globally complete picture of historical weather and climate, and extending the data record for global atmosphere, land surface and ocean waves to over 83 years, from 1940 to the present.

The reanalysis dataset is available from C3S and the ECMWF Meteorological Archival and Retrieval System (MARS). By the end of 2023, ERA5 had well over 125,000 users, ranging from researchers to professional consultants, big data experts, journalists, policy-makers and the public.

ERA5 has well over 125,000 users, ranging from researchers to professional consultants, big data experts, journalists, policy-makers and the public.

ERA5 makes use of all available observations, in-situ and from satellites. Although in the past observations were sparser than today, from 1940 ERA5 provides a good estimate of the actual situation for large regions over the northern hemisphere. The figure shows the representation of a severe storm over the Iberian Peninsula in 1941, which led to significant damage and disruption over Portugal and northwest Spain.

Three snapshots of the Iberian Storm of 1941, showing ERA5 mean sea-level pressure (contours, in hPa) and hourly maximum 10 m gusts (colours, in m/s). The locations of assimilated pressure and marine-wind observations from which the ERA5 reanalysis fields were constructed are shown as red dots.

The Iberian Storm of 1941

Three snapshots of the Iberian Storm of 1941, showing ERA5 mean sea-level pressure (contours, in hPa) and hourly maximum 10 m gusts (colours, in m/s). The locations of assimilated pressure and marine-wind observations from which the ERA5 reanalysis fields were constructed are shown as red dots.

Copernicus Health and Energy Hubs

CAMS and C3S launched two ‘hubs’ to help users in the health and energy sectors navigate the wealth of Copernicus data and information products. Each hub brings together information from all of the Copernicus services. ECMWF acts as the central contact point on behalf of the other entrusted entities for institutional user requests on any Copernicus-related data products within the domains of health and energy.

The Health Hub supports users working on physical and mental health, and wellbeing, by gathering information that was previously distributed and less accessible to people with limited experience in using data based on Earth observations. Such information is increasingly being used in the health sector, for assessing environmental drivers that affect health, such as temperature, humidity, air quality, UV radiation and the evolution of habitats for disease vectors. They can help stakeholders to make informed decisions, develop applications, and ultimately improve public health outcomes.

The Energy Hub supports the EU’s efforts to make Europe’s energy supply more sustainable and secure at a crucial time. Copernicus data provide invaluable insights to support energy production, from planning to distribution, enabling operators to improve energy efficiency and reduce emissions. For example, forecasts of global ocean physics and waves are important for the offshore wind, tidal and wave energy sectors, while solar radiation timeseries can be used to plan, monitor and improve the efficiency of solar energy systems and integrate them into energy supply grids.

Cloud computing for Europe’s meteorological community

A community cloud computing platform jointly operated by ECMWF and EUMETSAT became operational in September.

Called the European Weather Cloud (EWC), it provides a hub for the meteorological community in our Member and Co-operating States to collaborate and share resources.

Users can customise their applications and workflows, as well as build and expose services through the web. Running applications and services next to where the data is produced avoids large data movements over the network.

Most of the pilot use cases transitioned seamlessly into operational use. They include the use of the EWC as a collaboration platform on which training courses can be run, and by the South-East European Multi-Hazard Early Warning Advisory System (SEE-MHEWS) to make data produced at ECMWF by participating countries available to the other partners.

A workshop introduced users to new aspects of the EWC and ways to benefit from it, while two webinars in November gave an introduction for new and prospective users.

The national meteorological and hydrological services in southeast Europe participate in the South-East European Multi-Hazard Early Warning Advisory System (SEE-MHEWS) project, which uses the EWC to run the frontend web application displaying products generated by the partners at ECMWF they can all access.

Shared resources

The national meteorological and hydrological services in southeast Europe participate in the South-East European Multi-Hazard Early Warning Advisory System (SEE-MHEWS) project, which uses the EWC to run the frontend web application displaying products generated by the partners at ECMWF they can all access.

European State of the Climate 2022

The sixth annual European State of the Climate (ESOTC) report was published in April. Produced by C3S with contributions from national meteorological services, partners and other Copernicus services, the flagship report contains analysis of the past calendar year, with updates on long-term trends of key climate indicators.

The 2022 report included a snapshot of the global context, confirming that, globally, 2022 was the fifth-warmest year on record and the second-warmest year on record in Europe. Europe experienced its hottest summer on record, and summer wildfire carbon emissions were at their highest since 2007. The report detailed significant drought in Europe, as well as record loss of glacier ice in the European Alps, and the record surface melt experienced by the Greenland ice sheet in September 2022.

The findings were widely covered by media around the world, with the most media coverage and website traffic of an ESOTC to date. More than 100 journalists attended the briefing introducing the report’s findings. Later in 2023, we were able to engage further with policy-makers, for example with the German Embassy in Brussels, a Q&A session with the European Commission Directorate-General for Climate Action (DG CLIMA) and a presentation to the European Parliament Committee on Environment, Public Health and Food Safety (ENVI) in Brussels, to raise awareness of the report and its findings.

We also worked with the World Meteorological Organization to produce a joint State of the Climate in Europe report for 2022, which was published in June 2023.

The flagship ESOTC report uses consistent, dependable, freely available data that assist policy-makers in understanding climate change and its impacts.

Europe’s climate in 2022

The flagship ESOTC report uses consistent, dependable, freely available data that assist policy-makers in understanding climate change and its impacts.

Early warnings and climate data at COP28

ECMWF, C3S and CAMS brought expertise in the use of observations, modelling and technology to the discussions at the COP28 to help shape actions in the WMO’s priority areas at the United Nations Climate Change Conference: early warnings for all, the Systematic Observations Financing Facility (SOFF), water and climate, global greenhouse gas monitoring infrastructure, and climate science for climate action.

A joint ECMWF–SOFF event brought together partners to discuss how more observations and better forecasts could help climate adaptation efforts. Director-General Florence Rabier and Daniel Gellens, then ECMWF Council President, announced that ECMWF had approved real-time access to forecasts for 25 countries in relevant geographical areas as part of the scheme. Those countries would be able to use the four-day forecasts with a grid spacing of 9 km as boundary conditions to initialise higher-resolution limited-area models.

Through panels and meetings organised by international partners and extensive media engagement, C3S and CAMS demonstrated how their Earth observation data and climate services could support the green transition; climate monitoring; national planning, policies and reporting; and the Global Stocktake. On behalf of the EC, the two services organised an event that was broadcast live from Brussels, in which speakers from different domains discussed how climate monitoring, adaptation and mitigation required collaboration across different sectors.

As well as speaking on machine learning, we presented our work in the EU Destination Earth initiative, which contributes to efforts to boost Europe’s digital capabilities and the Green Deal actions on climate change.

The first set of countries receiving forecasts from ECMWF through the Systematic Observations Financing Facility (SOFF), located in Africa, Asia, Latin America, and the Pacific.

Real-time access to forecasts

The first set of countries receiving forecasts from ECMWF through the Systematic Observations Financing Facility (SOFF), located in Africa, Asia, Latin America, and the Pacific.

High-performance computing workshop

The 20th edition of the HPC workshop in October brought together over 140 people in Bologna, as well as 170 online registrants. It included 55 talks, 3 keynote talks from leading HPC specialists, plus an expert panel discussion and a tour of our data centre.

Predominant themes were realising the potential of HPC and artificial intelligence (AI), with rapid advances in machine learning techniques exploiting GPU technologies and the growth in cloud computing environments to tackle challenges associated with climate and weather prediction. Strong emphasis was placed on embracing the diversity of services and communities to realise the full research potential.

Predominant themes at the HPC workshop were realising the potential of HPC and artificial intelligence (AI).

Talks and the poster session took place at the San Domenico centre in Bologna.

HPC workshop

Talks and the poster session took place at the San Domenico centre in Bologna.

Using ECMWF’s Forecasts (UEF)

Our forecast users convened in June at our headquarters for the annual UEF to learn about the latest developments in ECMWF products and services. The UEF2023 on the theme ‘Ensemble forecasting’ was the largest ever UEF, with 80 attendees in person and up to 80 online at any one time. Discussions provided useful feedback on ECMWF products and services. In addition to presentations and posters from invited speakers, ECMWF staff and users, interactive sessions included the User Voice Corner, a re-forecasting session, and ensemble discussions on 12 questions exploring forecasting, research, data and outreach.

Attendees at ECMWF’s headquarters in Reading in June 2023.

Using ECMWF Forecasts (UEF)

Attendees at ECMWF’s headquarters in Reading in June 2023.

Annual Seminar

About 100 scientists and students came together in September for the Annual Seminar on the topic of Earth system reanalysis, in Reading and livestreamed. It was aimed at early career scientists as well as more established scientists wishing to engage more with reanalysis and to learn about the history and state of the art of Earth system reanalysis activities. There were 32 presentations and 22 posters.

Reanalyses provide gapless fields of historical weather and climate, as well as of the land surface, ocean waves, the ocean, hydrology, and atmospheric composition. They are usually a blend of observations with short-range forecasts rerun with modern forecasting models. Reanalyses are very popular datasets that are used for a wide spectrum of applications.

Destination Earth User eXchanges

Two ‘User eXchange’ events were co-organised by ESA, EUMETSAT and ECMWF to share progress with the Destination Earth (DestinE) community and to listen to users’ requests and feedback. Over 200 people from across Europe gathered for the 2nd Destination Earth User eXchange, which we hosted in Bonn, Germany, in November.

Presentations showed the main components of the future digital twin of the Earth system were taking shape and were soon to be assembled for the first tests. The event cemented these meetings as the forum for exchanges with DestinE stakeholders, building on the success of the first User eXchange in June.

Over 200 people attended the 2nd DestinE User eXchange forum in Bonn.

Destination Earth User eXchange

Over 200 people attended the 2nd DestinE User eXchange forum in Bonn.