Response of clouds and surface energy fluxes to changes in sea-ice cover over the Laptev Sea (Arctic Ocean)

The response of Arctic clouds to changes in sea ice extent is examined using the Polar version of the Weather Research and Forecasting (WRF) regional model over the Laptev Sea. Polar WRF output provides detailed information on cloud properties, such as liquid water path, ice water content, cloud height, and cloud radiative forcing during periods of low and high sea ice extent. The Polar WRF is run for 8 Septembers and Octobers selected for anomalously low and high sea ice cover, and analyzes differences in cloud properties, cloud radiative forcing (CRF), temperature, and the surface radiative and heat budgets. Clouds were more frequent and had larger liquid water paths during low than during high sea ice cover years. Increased surface longwave CRF during the low sea ice years only occurred in September. In September, the averaged cloud liquid water path during high sea ice years resulted in a cloud emitting close to its maximum longwave radiation, and increases in cloud liquid water path during the low sea ice years did not increase the surface longwave cloud radiative effect. In October, the averaged cloud liquid water path during high sea ice years did not result in a cloud emitting its maximum longwave radiation, and cloud liquid water path increases that occurred in the low sea ice years affected the surface cloud radiative effect. Clouds warmed the surface during periods of low sea ice cover in October.