Southern Hemisphere Sea Ice and the Atmospheric Boundary Layer in a High-Resolution Simulation of the Community Earth System Model

Abstract:

Increasing the horizontal resolution of the sea ice and ocean components in a global climate model has been shown to affect the extent of sea ice and the strength of atmosphere/ocean fluxes. Since existing high-resolution (0.1°) coupled simulations include a dynamical ocean, it is difficult to pinpoint how these results are influenced by the resolution of the sea ice. This project takes a closer look at the impact of sea ice resolution on ocean/atmosphere interactions in the Southern Hemisphere using the Community Earth System Model (CESM1-CAM5) in a slab ocean configuration. In this set-up, sea ice and mixed layer ocean models on a 0.1° grid (high resolution) or 1° grid (standard resolution) are coupled with atmosphere and land models run at the same 0.5° resolution. The high resolution model can produce fine scale, open water areas within the ice pack that facilitate air/sea flux exchanges and reduce the stability of the lower atmosphere in the model. Correlations between sea ice concentration and boundary layer variables will be described at different spatial scales to understand the effects of resolving small scale features. Finally, a kernel feedback analysis will be shown on a 0.1°, double CO₂ run to look at the impact of sea ice resolution on the regional lapse rate feedback.