ECMWF’s user meeting focuses on ensembles

Anna Ghelli


The theme of this year’s Using ECMWF’s Forecasts meeting (UEF 2019), which took place in Reading from 3 to 6 June 2019, was ‘The Strength of Ensembles’. The annual UEF meetings give ECMWF data users a unique opportunity to learn about the Centre’s plans, new products and services. They also foster networking and experience sharing. The reason why the meeting returned to the theme of ensemble forecasts is the recognition that the information about the probabilities of different scenarios provided by such forecasts improves the ability to make decisions in situations when the weather plays a role. UEF 2019 focused on four thematic areas: processing model outputs; visualisation; verification and diagnostics; and applications and impact forecasting.

Speakers’ Corner. Speakers gave a range of updates on new products, visualisations and applications.

Meeting highlights

Director of Research Andy Brown and Director of Forecasts Florian Pappenberger both addressed the meeting. Andy stressed the incredible amount of work that has gone into improving the seasonal forecast model and to move it towards a seamless system with a consistent approach to modelling from the medium to the seasonal forecast range. Another novelty, continuous data assimilation, enables the use of more up-to-date weather observations to help define the initial conditions for forecasts. This change, implemented in June this year, has significantly improved the quality of forecasts (see ECMWF Newsletter No. 158 for details).

Florian reminded his audience that the goals in ECMWF’s ten‑year Strategy to 2025 include the development of a 5 km ensemble. He noted that an intermediate goal to 2020 is a significant increase in our computational capacity, to be provided by the next high-performance computing facility, which will be located in Bologna. Florian added that over the next eight to ten years the number of observations used to build an analysis is expected to increase by a factor of ten; we will be producing 2,000 times more model data per day; and 100 times more data will be archived per day. As part of efforts to address this challenge, ECMWF is working with its key partners to set up a European Weather Cloud. The idea is to provide cloud services to bring users closer to our data.

Group photo. About a hundred external participants took part in the UEF 2019 meeting.

Central to the UEF is also the sharing of experiences on data access and use, facilitated by a dedicated Speakers’ Corner session. “ecCharts, the web application for visualising ECMWF data, has undergone changes to make it faster and easier to use,” explained Cihan Sahin while demonstrating the new capabilities during the session. ecCharts offers around 300 layers (parameters) from medium-range atmospheric and wave model fields, extended-range forecasts up to 6 weeks ahead, re-forecasts and Copernicus Atmosphere Monitoring Service (CAMS) products. New products, such as point rainfall, have been added to ecCharts (see ECMWF Newsletter No. 159 for more details).

Several plenary session talks illustrated the use of ECMWF data in a variety of sectors and applications. Sippora Stellingwest (Weather Impact) stressed that weather information should be easy to understand, localised and customised to have impact on human activities. For example, forecasts, and information on the confidence we can have in them, help to mitigate the impact of pests on plants, as illustrated by research results presented by Ivana Aleksova (Météo-France). Marine services benefit from the probabilistic information provided by ECMWF’s ensemble forecasts, as timely decisions can be taken days to weeks ahead of severe events to ensure the safety of personnel on oil rigs and to reduce economic losses.

Poster sessions have become a central part of the UEF. They offer a chance to discuss details of the piece of work presented and to seek future collaborations. Poster topics ranged from forecast performance in specific weather situations to newly developed products and the use of hourly to seasonal products in sectoral applications. An interactive poster provided feedback to ECMWF on the next dissemination schedule, which defines the way data is delivered to our data users. Currently ECMWF has a fixed dissemination schedule determining at which time individual products are released. A review of that schedule is being undertaken as part of preparations for the move of the data centre to Bologna.

Art and science

Art and science. A ’58‑member ensemble’ of forecasts was created during the art and science session.

An ‘art and science’ challenge highlighted the usefulness of an ensemble when predictability is relatively low. Participants were divided into groups and were briefed on the current weather situation and how it might evolve. It was down to them to produce a drawing showing what the weather might look like in five days’ time. The result was an artistic ensemble (58 members) which encompassed the observed outcome and some degree of uncertainty around it. Louise Arnal, the creator of the game, noted that “no team was able to capture the exact location and intensity of the event, but in combination all the drawings gave an indication of the future situation”. Well done to the winners!

And the winners are… The Twitter engagement winner was Leonard Smith from the London School of Economics (@lynyrdsmyth), while Claudia Stoker from MeteoSwiss and Biserka Frankovic from Crocontrol Ltd, Croatia, won the art and science competition. The photo shows (left to right) UEF 2019 organisers Julia Wagemann and Anna Ghelli; Claudia Stoker; and Lovro Kallin from the Croatian Meteorological and Hydrological Service, who accepted Biserka’s prize on her behalf.