What's so special here?
A recent HPC Wire article about climate change explained why simulation at such a fine resolution (7-kilometer) was so difficult, because it required:
a special allocation of computing time on the Athena supercomputer at the National Institute for Computational Sciences (NICS)... For six months, the entire 18,048-core system was at the disposal of the team. Among the results ... were simulations that represented boreal summer climatology at 7-kilometer resolutionNotice shifting cloud cover and precipitation in shades of gray scale during the summer months of 2009. The quality is exceptional.