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MeteoSwiss uses a 12 node cluster with 16 GPUs each to compute its weather forecasts (Piz Escha/Kesch). The machine is in operation since more than a year. We were able to disable the old machine (Piz Albis/Lema) last week.

The 1.1km forecast runs on 144 GPUs, the 2.2km probabilistic ensemble forecast is computed on 168 GPUs (8 GPUs or 1/2 node per ensemble member). The 7km EU forecast is run on 8 GPUs as well.

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What kinds of numerical algorithms are used for this? e.g. Monte Carlo or Finite Element Analysis?

It's a simple finite differences discretization on a rectangular grid. The computations are horizontally explicit and vertically implicit (data dependencies in the vertical direction).

Here's the scientific description of the model: http://www2.cosmo-model.org/content/model/documentation/core...

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