The role of stratospheric resolution in simulating the Arctic Oscillation response to greenhouse gases

Abstract

The Arctic Oscillation index has increased significantly over the past forty years, and such an increase has been simulated in response to greenhouse gas increases in several climate models. However, it has been suggested that an atmospheric model with an upper boundary in the upper stratosphere or mesosphere is required to simulate a realistic response, and that predictions made with standard climate models are hence unreliable. Here we show that a climate model with a 30-km upper boundary shows no increase in its surface Arctic Oscillation response to doubled carbon dioxide when its upper boundary is raised to 80 km. Neither model version shows a significant Arctic Oscillation response to stratospheric ozone depletion.