Many functions of digital ‘twins’

A research team led by Daniel Klocke from the Max Planck Institute for Meteorology has just put together a new digital model of Earth. They call it an Icosahedral Nonhydrostatic (ICON) model. It does weather forecasting and climate modelling.

- DEVANGSHU DATTA

ICON divides Earth’s surface intoagrid of 336 millioncells, with each cell representing 1.25 square km. Another 336 million cells represent the atmosphere. Each cell runs interconnected models reflecting dynamic weather and climate systems.

Weather is calculated by looking at “fast” systems like natural energy and water cycles, which induce short-term changes. “Slow” processes like the carbon cycle, long-term changes in the biosphere, ocean temperatures, and chemistry are also modelled to judge climate trends.

Combining fastand slow, ICON spits out weather forecasts and climate predictions. This is computationally intense. © ICON incorporates 1 trillion “degrees of freedom”, which equates to calculating about the same number of values. It improves drastically on earlier models which could, at best, handle only digital twins where each cell represents 40 square km.

Every day, ICON runs calculations for the next 145 days (145.7 daysto be exact). Apart from clever maths and software tricks, it needs humongous computing power. It uses two supercomputers, which run on arrays of over 20,000 GH200 Grace Hopper chips. Each chip com-binesaHoppergraphics processing unit (GPU) from Nvidia and a Grace CPU from ARM.