Sensitivity of the Thickness of Arctic Sea Ice to the Optical Properties of Clouds

The sensitivity of Arctic sea-ice thickness to the optical properties of clouds is investigated. Pollution aerosol has the potential to modify cloud optical properties significantly, which in turn could perturb the radiation balance at the surface of the pack ice. A one-dimensional thermodynamic model of sea ice is employed in this study. Radiative fluxes are parameterized in terms of integrated liquid (ice) water path and the particle effective radius. Results from these calculations show that, for a constant liquid (ice) water path, increasing cloud droplet concentration and the associated reduction in drop size results in a significantly altered surface radiation balance, contributing to an increase in sea-ice thickness. Considerable sensitivity has also been shown of the surface radiation balance to the frequency of occurrence and optical depth of lower tropospheric ice crystals that are present during the cold part of the year.