If you want to visualize the surface air flowing across every meter of the planet Earth, you need to plot nearly three trillion squares of land and sea and space. To do that you need a mind-bogglingly big calculator. Which is why Ioan Hadade, a computational scientist working with vast weather forecasting and climate models, is excited about the machine now online an hour down the road from his lab in Bonn, Germany.

Europe’s first exascale supercomputer—called JUPITER, after a much bigger planet than our own—is nearly fully operational. It is currently running scientific programs on its formidable processors. JUPITER debuted at No. 4 in the June 2025 global TOP500 list of the world’s most powerful computer systems. It is based at the Jülich Supercomputing Center in the German Rhineland between Cologne and Aachen, running on a booster module with 5,900 accelerating compute nodes. Some 24,000-odd Nvidia Grace-Hopper superchips

give JUPITER its oomph; the machine also features a universal cluster module with 1,300 nodes using Rhea1 processors, and an InfiniBand NDR network for the high-speed interconnects. The semi-annual TOP500 rankings are a way to engage every single element of a machine for performance. Benchmarking proves the functionality of a highly complex operation. “And now, it’s better to have some science done on the machine,” says Thomas Lippert, director of the Jülich Supercomputing Center. Computational Science at Scale As of mid-June research enterprises were on the JUPITER machine testing scientific calculations. “You need a really large machine to run this,” Hadade says. He’s referring to the Destination Earth digital twin projects he and his colleagues are part of developing at the European Center for Medium-Range Weather Forecasts.

The Destination Earth digital twins are replicas of Earth systems used to monitor, simulate, and predict the interaction between natural phenomena and human activities. Hadade and his colleagues have produced physics-based observations of atmospheric conditions and weather at 9-kilometer resolutions and closer. Being able to zoom in—to show physical phenomena at a resolution of 700 meters or finer—reveals the processes that prompt deep convection and turbulence.

The team is turning to JUPITER to do it. Across the country at the Technische Universität Ilmenau, physicist Jörg Schumacher is investigating convection and turbulence by visualizing the intricate flow of thermal plumes, the kind you might find within cloud formations or, in a more violent state, on the surface of the sun. Convection is driven in the simplest case by the flow of fluids or gases through different temperature bands: You could have a hot bottom and cold top layer, and if the temperature difference is strong enough, it starts to get very turbulent between them. Highly nonlinear filaments, vortices, and eddies start forming patterns and structured networks. “Everything should be very chaotic, irregular, stochastic—but it isn’t,” Schumacher says. “How is nature forming these nice beautiful patterns in highly turbulent flows?”