Continental-scale convection-resolving climate simulations

ETH scientists perform a Pan-European climate simulation using a computational mesh fine enough to simulate thunderstorms and rain showers.

by Urs Beyerle

Using a new version of the weather and climate model COSMO, capable of using novel supercomputers employing GPU accelerators, external pageLeutwyler et al. (2017) performed a 10-year-long climate simulation at 2.2 km resolution on a domain covering continental Europe (1536x1536x60 grid points). The paper has been selected as a publication highlight by external pageAGUs Earth & Space Sciene News.

Thunderstorms and rains showers (deep convection) are difficult to simulate in today’s climate models. The computational meshes used today are usually too coarse (10-200 km) to catch the associated small-scale motions. Therefore, these models treat deep convection using physically-based semi-empirical parameterizations. In the current study the grid spacing is refined to the kilometer scale, which allows switching off these parameterizations and thus formulating the model much closer to physical first principles.

Enlarged view: Summertime convection in continental Europe
Summertime convection in continental Europe. Snapshots on 13 June 2006 12 UTC from (left) a simulation with parameterized convection and (right) with deep convection treated explicitly. The colored shading denotes the 15min-precipitation [mm/h], and the grey shading a cloud visualization.

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