Accomplishments, community-building, and a plot contest. This is what happened on the final day of the Stockholm hackathon.

After four days of hacking and collaborating together, March 28th, 2025, marked the final session of „The Final Countdown“ hackathon in Stockholm. Focused on the possible applications of Storm-Resolving Earth System Models (SR-ESM) in the renewable energy sector, this was also the last hackathon of the nextGEMS project. Some extraordinary accomplishments were made during the past 5 years since the start of this visionary project. The group was, for example, able to create 10, 5, and 2 kilometer-scale runs, and are close to release runs with a resolution of 1 kilometer. However, nothing stands out more than the solid and compromised community nextGEMS has built up through the years: talented and curious people working together to push forward high-resolution climate modeling and understanding the possibilities it comprises for a warming and changing planet.

The last hackathon day involved a small plot contest, won by scientist Matthias Aengenheyster from the European Center for Medium-Range Weather Forecasts (ECMWF). His visual shows wind gust speed and 2-minute averaged precipitation in an area around Japan for the coupled IFS-FESOM model simulation at 2.8 km resolution. Near the bottom, a tropical cyclone is approaching Japan, while another one near the top is transitioning from inter-tropical to an extra-tropical cyclone as it moves to cooler latitudes.

Plot by Matthias Aengenheyster — Wind gust speed and precipitations around Japan, created with the IFS-FESOM simulation at 2.8 km resolution. Credits: Matthias Aengenheyster.

During the closing session, the five thematic groups were able to share their advancements with the audience. For instance, the Renewable Energy group talked about their efforts to monitor wind speed shifts in the central Sweden region with nextGEMS’ climate models, where some of the stakeholder companies had placed wind turbines. In parallel, the Storms & Radiation team shared their intentions to prepare 3 thematic research papers on diverse topics, such as climate sensitivity, feedback decomposition and tropical cloud organization—the last one with a special focus on deep convective clouds.

Hackathon participants — Participants listening to presentations during the last day of the Stockholm hackathon. Credits: nextGEMS.

In an engaging presentation, some of the early-career scientists and first-time hackathon attendees who participated in the Storms & Land group, provided interesting insights of the snow coverage observations in the Iberian mountain range. Similarly, the Storms & Ocean team share their observations of mesoscale ocean circulation patterns (typically between 10 to 500 km in diameter) occurring at shallow depths, as well as their interest of observing the historical future of “El Niño” phenomenon. The Storms & Society thematic group conducted several interviews during the event and disseminated a final survey with the participants to finish their work on Climate Science storylines and the impact of hackathons in knowledge co-production.

Finally, Climate Physics Director at the Max Planck Institute for Meteorology, Bjorn Stevens, closed the event remarking some of the useful applications nextGEMS’ models have enabled, such as testing hypotheses underpinning climate change, studying changes at the mesoscale or blocking statistics, and the representation of hydrological extremes worldwide. Furthermore, he mentioned some of the forthcoming activities for the community, spearheaded by nextGEMS, such as the upcoming Global Hackathon taking place in May, 2025.

Group picture Stockholm — Group photo during the final day of the Stockholm hackathon. Credits: Latest Thinking.

The nextGEMS project has entered its final phase and will come to an end in August, 2025. But before going separate ways, our project members and partners gather one last time for the sixth nextGEMS hackathon from March 24th to 28th. In the stylish surroundings of Stockholm city, the Swedish Museum of Natural History, the largest museum of the Nordic country, hosts “The Final Countdown”. This time, the participants´ challenge is centered around how the high-resolution capabilities enabled by nextGEMS simulations can support and enhance renewable energy applications in a changing climate.

Clear-sky morning at the Swedish Museum of Natural History in Stockholm. Credits: nextGEMS

The first day kicked off with the arrival of a diverse group of scientists, stakeholders, students, and climate enthusiasts that totaled 73 registered participants. Within the museum´s classic setting, the introductory session evolved into an active and engaging conversation. Representatives from the Max Planck Institute for Meteorology (MPI-M) and the European Center for Medium-Range Weather Forecasts (ECMWF), updated the audience on the progress being made with the simulations of the ICON and IFS-FESOM Earth System models.

Tobias Becker, researcher from the ECMWF, presented insights on two simulations at 2.8 km resolution, produced with 14 months of new data using the IFS-FESOM model. These recent advancements add local granularity and allow to check if atmospheric phenomena previously analyzed at coarser or less detailed resolutions also show up at this higher resolution. Additionally, he reported on two 30-year simulations – historical and scenario-based – at 9 km resolution that should provide valuable information on how extreme events change in warming climate, such as tropical cyclones.

Hackathon participants in the auditorium during the introductory session. Credits: nextGEMS

The different thematic groups—Storms & Land, Storms & Ocean, Storms & Radiation, and Storms & Society— discussed their newest achievements and upcoming challenges. Dragana Bojovic, from the Storms & Society group, for example, talked about the survey analysis from the past five hackathons, as well as of the work on renewable energy and fisheries storylines. This time, a new group joined the Stockholm hackathon: the renewable energy group. This group includes not only researchers, but also different industry stakeholders, such as people working at Vestas, Satkraft, Anemos, and local participants, addressing future energy scenarios for 2050.

Matthias Aengenheyster updating the audience about the IFS-FESOM model advancements. Credits: nextGEMS

To conclude the day, participants took part in an ice-breaker session, which included a micro-poster activity designed to enrich conversations and connections through the use of visualizations. Some of the first-time participants in the event, like Diego Garcia and Antonio Robles from Universidad Complutense de Madrid in Spain, shared posters illustrating their observations on historical data regarding snow coverage along the Spanish highlands and future changes in Tropical Basin interactions, created with the IFS-FESOM model.

Newcomers from Spain sharing the scientific posters at the ice-breaker session. Credits: nextGEMS

by Thorsten Mauritsen, MISU

Model performance in the renewable energy sector

By directly and more physically simulating specific events (e.g., tropical cyclones, rainfall extremes, blockings) most associated with hazards, nextGEMS provides an improved basis for assessing risk globally. The importance of simulating fine scales for assessing hazards, but also for other applications, is well understood and motivates the patchwork of downscaling approaches known as the value chain. A Challenge Problem, co-defined with stakeholder groups, hereby, will help guide the development of the SR-ESMs, and their associated workflows, in ways that better expose their information content to application communities. This will allow us to “short-circuit” the value chain and develop a new model of Integrated Assessment. Activities are planned in the form of pilot projects on near surface (wind/solar) renewable energy, marine productivity, and changing weather or climate related hazards.

For the challenge problem in the renewable energy sector, we addressed specific challenges:

Challenge 1: What is the minimal amount of information needed to optimize the design of a regional renewable energy system and how can we extract this information from global storm-resolving models.

Challenge 2: How does the potential renewable energy output landscape change with a changing climate?

During the Cycle 2 Hackathon our stipends were provided with meteogram station data from two different models. Along with temporally sparse snapshots of full three dimensional model output. The main goal was to either find a condensation of the high-frequency output or suggest other output variables, to support the design of renewable energy systems.

Support was given by technical consultants (members of the modelling groups) to help them understand the model output and ways of accessing it since the focus shall lay on the science rather than solving technical problems.

Additionally, the teams were supported by energy consultants, to for instance help them understand design parameters (hub height, diffuse versus direct efficiency, etc.). In particular we had two sessions with Iberdrola and with Vestas Wind Systems. These sessions were particularly useful for the participants to understand the problems that the energy industry is facing, and provided an opportunity to discuss their results with experts. There was also a discussion of how the participants potentially develop a carreer in the renewable energy sector.

Expert interacting with Hackathon participant.

Findings during the Cycle 2 Hackathon

The approach taken in the Hackathon is to use the ability of the nextGEMS models to resolve the mesoscales and represent relevant motion and fields for renewable energy production. We used primarily dedicated high frequency output for a series of stations, but also the complete mapped output.

For example the wind at rotor height of a typical wind power plant around 100 m above ground is used directly to calculate the power output from a typical turbine. Figure 1 shows how the output depends on the wind speed. The output starts at a minimum wind speed and increases with the wind speed to the third power up to a maximum value which is limited by the generator size. At high wind speeds the turbines automatically turn off to limit wear and for safety reasons.

Because the power output curve is highly non-linear in the wind speed, we were interested in seeing how much estimated power is biased if using lower temporal resolution. Figure 2 shows output for four different stations. First we note that estimated output is monotonically decreasing with lower resolution suggesting that all stations, except perhaps the EURECA ocean site, are mostly seeing winds on the qubic wind speed range. For this a different combination of turbine, generator and tower height can be used to extract more energy at these sites. We also see that the bias is very low when degrading from 3 minute to 1 hour means, and even monthly mean wind speeds provide a reasonable estimate. Here it is important to note that this is the average of the instaneous wind speed. If the wind components were average the degradation would be much larger.

Figure 1. Dependency of power output to wind speed.

Figure 2. Power output for four different stations.

Model Performance

We checked how the models perform in terms of representing the observed wind speed at the flat surface Cabauw site in the Netherlands. It turns out that both the IFS and ICON grossly underestimates the occurrence of high wind speeds.

This bias in both the IFS and the standard ICON-Sapphire setup is related to the parameterisation of turbulent drag. This can be seen from the 10 km resolution test simulation conducted using the TTE scheme, which exhibits a more realistic distribution at Cabauw (see figure 3).

Solar Power generation

Figure 4 shows a comparison of the monthly mean modelled downwelling shortwave radiation with observations at the Cabauw site. Here both IFS and ICON do a good job in predicting the observations. Also, the IFS model was analysed in three different resolutions but there is no obvious difference.

To convert the downwelling shortwave radiation to power output one must take into account various losses, here assumed to amount to 12 percent, as well as the temperature degradation, here assumed to be -0.5 %/K (see Figure 5.)

Figure 4. Model performance compared to observations throughout the year for Cabauw, NL.

Figure 5. Left panel shows a map from ICON of the solar energy reaching the surface in kW hours per year. To the right the maximum which can be extracted with such panels. We see that although there is a lot of radiation available in the sub-tropics, e.g. the Sahara, much of this advantage is counteracted by the warm temperatures.

Challenges for the renewable energy industry

What became clear through the Hackathon was that the wind industry is already working with quite advanced modelling tools for site planning and short term forecasting of wind power, along with on site observations. The situation is slightly less advanced for solar power, partly because the modelling tools are not nearly of the same quality due to problems with modelling clouds. New demands on the industry to also assess the impact of the changing climate on production, safety and durability/maintenance needs is a challenge that the industry is not well suited to meet, and where more research is urgently needed. Also, industry is looking forward to leveraging DestinationEarth digital twin simulations in their workflow.