It was a very busy and successful year engaging and sharing knowledge and expertise with Member and Co-operating States and users, with operations and innovation maintained through the pandemic restrictions thanks to our dedicated staff, reliable IT infrastructure and online resources.

Many developments in 2021 aimed to maximise the quality, usefulness and accessibility of our products, helping national meteorological and hydrological services in our Member and Co-operating States to produce weather forecasts and early warnings of severe weather.

The year was notable with two Integrated Forecasting System (IFS) upgrades bringing improvements in forecast skill and new and improved products. Extreme temperatures and heavy rain during the summer in Europe were well predicted by ECMWF forecasts, while consequences such as flooding and wildfire emissions were forecast and monitored by the EU Copernicus services we run or contribute to.

The release of more of our products as open data and of additional Copernicus datasets gave more users access to high-quality weather and climate data.

Our membership continued to expand as we welcomed Georgia as our 12th Co-operating State in December, and through the opening of our data centre in Bologna and offices in Bonn, our presence in and engagement with Member States strengthens. We signed an agreement with the European Commission to continue implementing the Copernicus Climate Change Service (C3S) and Copernicus Atmosphere Monitoring Service (CAMS) for the next seven years, and our role as the computational centre for the hydrological forecasting activities of the Copernicus Emergency Management Service (CEMS) was renewed for a further six years until 2027.

A summer of extreme weather

The European summer of 2021 stands out for heavy rain, which brought devastating floods, and also for great heat, which came with regional fires.

A period of intense rainfall in July, especially over parts of Germany and Belgium, led to devastating floods in some areas.

ECMWF high-resolution forecasts predicted with high confidence the broad location and intensity of the rain three days in advance.

Predicted rainfall
Predicted rainfallThe charts show the predicted rainfall in the 24-hour period starting on 14 July 2021 at 06 UTC, 78 hours in advance (left) and recorded amounts in the same period (right).

Flood forecasts from the European Flood Awareness System (EFAS) also indicated points on the river network where the flood signal was predicted to exceed the 1-in-5-year flood return period threshold. EFAS is part of CEMS, for which ECMWF is the computational centre for the hydrological forecasting activities.

Europe experienced its second-warmest June on record, with temperatures 1.5°C higher than the average for 1991–2020, according to the Copernicus Climate Change Service. It also experienced its second-warmest July, with temperatures 1.4°C above the average, while August was close to the 1991–2020 average, making the period June–July–August the warmest European summer. Particularly high temperature anomalies were recorded in the eastern part of the continent.

The Mediterranean experienced a long and exceptionally warm heatwave during July and August, which gradually shifted from east to west. On 11 August, a provisional new temperature record for Europe, of 48.8°C, was set in Sicily. The ECMWF Extreme Forecast Index (EFI) showed a consistently strong signal for the extreme temperatures up to a week ahead.

The high temperatures contributed the development of regional fires, and their emissions were forecast by the Copernicus Atmosphere Monitoring Service. According to CAMS, global wildfires in 2021 caused an estimated total of 1,760 megatonnes of carbon emissions, 148% more than the total EU fossil fuel emissions in 2020.

Extreme heat
Extreme heatECMWF Extreme Forecast Index for 2-metre maximum temperature on 11 August, from 144–168 hours before.

Forecast performance

We maintain a comprehensive range of verification statistics to evaluate the accuracy of ECMWF forecasts to ensure we meet our goals of providing high-quality products. In 2021, medium-range ensemble forecast skill reached a new record high. Summer performance has been consistently high over the last three years, and winter 2020/21 showed the highest skill ever. In Europe, the highest-ever 12-month running mean was reached.

Compared to forecasts from other global centres, ECMWF maintained the overall lead for upper-air parameters in the medium range. For surface parameters, especially in the short range, some of the other centres have drawn closer to ECMWF. The upper-air meteorological forecast performance of the CAMS forecasting system was similar to that of other global centres.

The IFS upgrade to Cycle 47r2 in May increased the number of levels in the vertical for the ensemble forecast (ENS), leading to a small but statistically significant improvement in upper-air ENS skill.

A second upgrade in October, to IFS Cycle 47r3, included a major upgrade to the moist physics of the model, resulting in more realistic precipitation characteristics. Together with a number of other changes, this cycle brought small improvements in upper-air skill in the early medium range.

Position errors for forecasts of tropical cyclones were smaller than in 2020, but the decrease was paralleled by forecasts based on the ERA5 reanalysis system, which indicates it was part of natural variability.

As in previous years, ECMWF has a modest but consistent lead in ocean wave forecasting over other centres in terms of significant wave height.

The skill of the Extreme Forecast Index (EFI) for 2-metre temperature increased, and we saw a significant improvement for 2-metre temperature in week three.

ECMWF’s seasonal forecast system, SEAS5, predicted the change from La Niña conditions in the equatorial Pacific at the end of 2020 to more neutral conditions in 2021 reasonably well. Due to the absence of strong tropical forcing in 2021, the skill of the extratropical seasonal forecast was relatively low.

Ensemble skill
Ensemble skillMedium-range ensemble forecast skill reached a new record high in 2021. This ensemble forecast headline score shows the lead time at which the continuous ranked probability skill score (CRPSS) for 850 hPa temperature in Europe drops below 25%. Red lines show 12-month running mean values, blue curves show 3-month running mean values.

Several new products were introduced following requests from Member and Co-operating States.

New and improved products

With the upgrade to IFS Cycle 47r2, we started operationally disseminating tropical cyclone track products from the 06 and 18 UTC runs as ‘WMO Essential’ products, including a graphical product. Users now have access to four sets of runs per day for these high-impact phenomena. The seasonal forecast products for tropical cyclones were revised to better account for the forecast’s inability to capture observed trends.

Working with the UK Met Office, we upgraded our extratropical cyclone product suite in May, making the products cleaner, clearer, less costly, more supportable and more future-proof.

With IFS Cycle 47r3 in October, we introduced several new products following requests from users across our Member and Co-operating States, such as new improved convective available potential energy (CAPE) output developed in close collaboration with the European Severe Storms Laboratory, and a clear-air turbulence product developed with the German Aerospace Center (DLR). The diagnostic should be useful for both forecasters and research in turbulence, particularly the development of turbulence parametrizations in the free troposphere and stratosphere. Improved visibility and wind gust forecast products were also introduced.

Clear-air turbulence (CAT) product
Clear-air turbulence (CAT) productExample of a high-resolution forecast of the average CAT (m2/3s-1) at 11,800 m (flight level 385). Data is provided on model levels and on specific flight levels on request by the Member States.

C3S’s flagship reanalysis product, ERA5, offered considerable analytical support to the IPCC Working Group 1 sixth Assessment Report released in August, being referenced over 200 times throughout the report. C3S continued to release new and updated datasets providing improvements to the empirical evidence needed to understand the current climate and better predict changes. These included a back-extension for the ERA5-Land reanalysis dataset. This dataset is the first of its kind, providing global, hourly, historic and high-resolution land-focused information, and now covers the whole period from 1950 to the present.

Move to open data

We continued the move towards providing open data products covering the whole world. This is a key aspect of increasing the availability and impact of hundreds of real-time forecast maps and products to organisations and individuals in Member and Co-operating States and beyond.

Downloads of OpenCharts dramatically increased from about 50,000 each day following the release in autumn 2020 to an average of 190,000 a day in autumn 2021, when we added more than 50 new products and increased the number of available forecast steps. In the summer we made an application programming interface (API) available for downloading the products. It follows OpenAPI specifications and offers documentation and an interactive test environment. A new feature called ChartSet allows users to see their selections side by side and change time steps or areas in one click for the entire set of selected products.

The free charts are based on the popular ecCharts licensed products, used by professional forecasters in ECMWF’s Member States, for example. OpenCharts aims to provide key information from the vast suite of tools available for ecCharts, delivering a pre-generated set of forecast charts that are of wide use to a broad audience.

VisibilityOne new forecast parameter available in OpenCharts is visibility. In response to user feedback, the product, which was one of several to be upgraded in IFS Cycle 47r3, represents the real-life situation much more accurately.

Resources for the weather and climate communities

We continued developing tools and services to improve user access to our computing and data resources.

ECMWF’s Metview software provides straightforward ways to access, process and visualise ECMWF forecasts and related data. 2021 saw the addition of new features for post-processing meteorological data. We also added new Python-based functions to Metview to meet the needs of users wishing to use new environments like Jupyter Notebooks for exploring large datasets.

Participants at our new hands-on introduction to NWP modelling training course used the new features to create datasets to work on a case study for a past storm event.

The US National Oceanic and Atmospheric Administration (NOAA) announced it would use the Global ECMWF Fire Forecasting (GEFF) model, which is publicly available, for its operational forecast. The GEFF model is also used by the Copernicus Emergency Management Service.

To ensure timely use of our data, we developed a new system called Aviso which notifies users when real-time forecast data or derived products are available and triggers user-defined workflows. By the end of the year there were roughly 400,000 notifications daily. The pre-operational Aviso service has been available since the beginning of 2021 to users of the European Weather Cloud, with some Member States exploring its advantages by executing time-critical workflows in the European Weather Cloud.

Aviso notification system
Aviso notification systemEvents submitted to Aviso from the ECMWF data flow. The goal is to enable time-critical workflows across HPC and Clouds.

The European Weather Cloud is a joint ECMWF and EUMETSAT project to create a cloud computing infrastructure for the meteorological community. In this third and final year of the pilot phase, the European Weather Cloud allowed us to support hands-on practical training sessions by providing remote access to individual lab instances running on the cloud with all the required software, tools and training material. The instances were equipped with JupyterLab, which allowed students to easily connect through their browsers.

We held two joint workshops with EUMETSAT for users in the Member and Co-operating States of our two organisations to give updates on developments. In December, the ECMWF Council decided to go ahead with the operational phase and a tender was issued for the technical infrastructure.

The C3S Climate Data Store (CDS) is an invaluable resource for a wide variety of users, providing easy access to a range of climate datasets and a toolbox for users to build workflows and applications. In October the number of registered users reached 100,000. New datasets added include the CMIP6 dataset – the most up-to-date, scientifically advanced database for climate science and services.

Atmospheric composition global forecasts from CAMS were made available through the CAMS Atmosphere Data Store (ADS), making the data much easier to access and use.

Ten years of OpenIFS

The OpenIFS, a complex operational numerical weather prediction (NWP) model, marked ten years’ operation in December, and its original aims since it began in 2011 remain relevant today: providing and supporting versions of the operational IFS for research, education and training in NWP and meteorology for the benefit of Member and Co-operating States’ meteorological services, academic institutes, and the wider community.

Over the decade, OpenIFS has produced improvements in the IFS; established a growing user community amongst Member and Co-operating States; enabled new collaborations; increased research and training opportunities in universities; created an international scientific workshop series; and improved knowledge of the IFS and ECMWF in the wider meteorological community.

OpenIFS licensees in Member and Co-operating States
OpenIFS licensees in Member and Co-operating StatesThe map shows the locations of most OpenIFS licensees. The growth in the number of OpenIFS licensees in recent years was in part driven by the steady adoption of the OpenIFS model by EC-Earth consortium partners.

Ease of use, dedicated support from our team, an OpenIFS workshop series, and training in online user guides and public forums have helped the external use of the IFS to be successful and of great benefit to the wider community.

The number and range of research and teaching applications using OpenIFS over the last ten years are impressive, including many NWP studies often featured in peer-reviewed literature or our Newsletter articles.

OpenIFS has also been the focus of several Earth system modelling groups. The EC-Earth consortium (which includes 30 research institutes from 12 European countries collaborating on the development of an Earth system model) have chosen the OpenIFS model as the atmospheric component of their next model release, whilst other research groups are working to build their own Earth system models based on OpenIFS.

OpenIFS has also played a key role in collaboration with the University of Oxford on the use of reduced precision in the IFS. This led to significant savings in computing resources at ECMWF for operational forecasting. OpenIFS was ideal for the proof-of-concept development as its reduced code base allowed rapid prototyping and testing.

A new hands-on introduction to NWP course included practical experiments using OpenIFS.

Knowledge-sharing and support for the scientific community

All our events and training activities remained on virtual platforms in 2021 due to the ongoing COVID-19 pandemic and varying international restrictions. As technology and requirements changed, we continued to develop our digital event offer, making the most of the technology available to foster scientific engagements with Member and Co-operating States, members of the European Meteorological Infrastructure (EMI) and the wider user communities.

Our workshops saw attendance increase by just over a third from 2020 to 2,911 registrants in 2021, and training course attendance almost doubled to 676 registrants. This remains significantly higher than pre-pandemic times, while also reducing the carbon footprint through virtual events. Naturally, staff and participants missed face-to-face engagement, but we are optimistic about serving Member and Co-operating States and the wider scientific community in hybrid formats in 2022.

Virtual workshops
Virtual workshopsThe platform was used for interactive activities at our training courses and workshops and to facilitate networking opportunities for attendees.

The flexibility of technology and the reduced need to travel enabled us to host shorter events, including a Science and Technology Seminar series featuring Destination Earth; machine learning for numerical weather prediction; and aircraft data, COVID-19 and global weather forecasting. The series was popular and attracted 1,748 viewers.

Faced with another period of online training, we set out to replicate the classroom practical learning experience as far as possible in our NWP training courses.

Over 130 participants were taught in our virtual classroom. In May we were able to run a new hands-on introduction to NWP training course that included practical experiments using the OpenIFS model.

To further increase the reach of training, we introduced a pilot scheme offering two levels of participation in learning events.

In May a joint ECMWF and OceanPredict workshop provided a forum to link oceanic and atmospheric communities helping to identify priorities for developments in ocean data assimilation methods. The collaboration with OceanPredict – a science programme for the coordination and improvement of global and regional ocean analysis and forecasting systems – was timely as 2021 marked the beginning of the UN Decade of Ocean Science for Sustainable Development and it will help the joint efforts planned under this.

Joint ECMWF and OceanPredict workshop
Joint ECMWF and OceanPredict workshopMore than 170 scientists from around the world discussed progress and challenges in ocean data assimilation.

Experts from different domains addressed the multidisciplinary science underpinning climate and environmental monitoring and predictions, the exploitation of novel observations, and interactions between the ocean, atmosphere, sea ice and biogeochemistry at global and regional scales.

Later in the year, further flagship events brought together experts from across national weather services, academia and industry, all held virtually.

The Using ECMWF Forecasts (UEF2021) meeting on the theme ‘Weather in extraordinary circumstances’ attracted 228 people from 53 countries. During UEF, we opened a new forum where users can interact with each other and our staff by posting comments and joining conversations on topics related to weather and forecasting. Any feedback received may be used in our ongoing research and diagnostics work.

The Annual Seminar provided an Earth system view of observations, with 520 participants exploring how effectively the current observing system is being used for NWP and reanalysis, and science and technical issues common to observations. It was held jointly with the WCRP-WWRP Symposium on Data Assimilation and Reanalysis. The 19th edition of our high-performance computing (HPC) workshop was entitled ‘Towards Exascale Computing in Numerical Weather Prediction’. The events were well received, with feedback and discussions featuring prominently.

We developed a user-friendly learning web page as a signpost to all our learning resources, which range from in-person and online training courses to e-learning lessons and webinars, as well as articles on topics related to forecasting, research, and computing.

C3S published its annual European State of the Climate, with contributions from national meteorological services and the other Copernicus services. The 2020 report included an overview of the global context, a more comprehensive overview of conditions in Europe, and a focus on the Arctic. Its findings were widely covered by media from around the world.

Copernicus data for policymakers
Copernicus data for policymakersThe European State of the Climate Report, published annually by C3S, is an example of the consistent and dependable Copernicus data that policymakers can use to understand climate change and its impacts.

As in previous years, CAMS tracked the formation and evolution of the Antarctic ozone hole. The 2021 ozone hole was one of the largest and longest-lived on record, attributed to very cold temperatures in the stratosphere and a very stable polar vortex.

CAMS scientists continued to contribute to research on the relationship between COVID and air quality. They collaborated in a study led by the London School of Tropical Hygiene and Medicine on air pollution levels in Europe during spring and early summer 2020, with results to be published in a peer-reviewed paper early in 2022. They examined the quantitative effects of reduced pollution levels and, for the first time, compared quantitatively the impact of different policy measures that were taken.

The signing for this new phase allows our Copernicus services to continue critical work in supporting Europe’s climate change mitigation and adaptation policies across many sectors from agriculture to energy.

New phase of Copernicus

In July we signed an agreement with the European Commission to continue implementing the Copernicus Climate Change Service (C3S) and Copernicus Atmosphere Monitoring Service (CAMS) for the next seven years. This new phase builds on the success of the first, which began in 2014.

The services are part of the EU’s Copernicus Earth observation programme, which draws data from satellite and in situ (land, air and sea) stations to monitor our planet and its environment through six streams.

The signing for this new phase allows our Copernicus services to continue critical work in supporting Europe’s climate change mitigation and adaptation policies across many sectors from agriculture to energy.

It will help decision-makers move forward with their roadmaps and evidence-based frameworks towards the goals of both the Paris Agreement and the European Green Deal, which aims to make Europe the first climate-neutral continent by 2050.

Separately, our role as the computational centre for the hydrological forecasting activities of CEMS was renewed for a further six years until 2027. The computational centre helps to deliver the European and Global Flood Awareness Systems, EFAS and GloFAS.

With Météo-France as a partner, we also submitted a proposal to support the operations and further enhancement of the European Forest Fire Information System (EFFIS) and to contribute to the development of the Global Wildfire Information System (GWIS), which are also part of CEMS.

ECMWF and Copernicus
ECMWF and CopernicusECMWF implements and contributes to services providing free-to-use data on climate change, atmospheric composition, flooding and wildfire prediction.
© Gilberto Martin/iStock/Getty Images Plus; ABBPhoto/iStock/Getty Images Plus; gemphotography/iStock/Getty Images Plus; Gilitukha/iStock/Getty Images Plus

Extending European partnerships

We continued to enhance synergies with Member States and other collaborations through the signing of new Memorandums of Understanding (MoU) during 2021, as well as our ongoing informal partnerships.

The Secretariat of the Union for the Mediterranean and ECMWF signed an agreement in October establishing cooperation to maximise the uptake and impact of the Copernicus services implemented by ECMWF, and to make best use of the products, services and tools developed or made available by C3S and CAMS to support the implementation of relevant EU and UN policies. Regular consultations have been agreed, and joint meetings twice a year will ensure the cooperation continues to achieve its aims.

During COP26 in November, we signed an agreement with the European Investment Bank to support it with enhanced use of Copernicus data for its climate and atmosphere monitoring data needs and ambitions to support climate change adaptation and mitigation activities by becoming the EU’s Climate Bank.

In addition, an MoU was prepared to be signed with the University of Bologna and an MoU finalised and ready to be signed with the Italian Government regarding collaboration on the Copernicus Mirror Programme, strengthening formal and informal collaboration.

Following approval from our Council in December, we became part of the European Union’s ground-breaking Destination Earth initiative that brings together scientific and digital technology excellence from across Europe.

The ECMWF contribution agreement covers the first 30 months of a seven- to ten-year programme.

With the existing Copernicus Programme, the newly created DestinE initiative, and our partnerships in Europe, we are contributing to and creating tools, infrastructure and capability to better plan and act for our planet’s future.

New partnership with European Investment Bank
New partnership with European Investment BankECMWF Director-General Florence Rabier (left) and EIB President Werner Hoyer signed a Memorandum of Understanding at COP26 in Glasgow.