Improvements in a half degree atmosphere/land version of the CCSM

A decadal climate projection between 1980 and 2030 using a nominal 0.5A degrees resolution in the atmosphere and land components has been performed using the Community Climate System Model, version 3.5. The mean climate is compared to a companion simulation using a nominal 2A degrees resolution in the atmosphere and land components. The increased atmosphere resolution has several benefits, and produces a significantly better mean climate. The maximum sea surface temperature biases in the major upwelling regions, including the West Coast of the USA, are reduced by more than 60%. Precipitation patterns are improved in the summer Asian monsoon, mostly due to the better resolved orography, and in the eastern tropical Pacific Ocean south of the equator. The improved precipitation patterns lead to better river flows in many rivers worldwide. The atmospheric circulation in the Arctic also improves, which leads to a better regional sea ice thickness distribution in the Arctic Ocean.