Arctic Cloud Properties and Radiative Forcing from Observations and their Role in Sea Ice Decline Predicted by the NCAR CCSM3 Model During the 21st Century

摘要: Arctic sea ice is sensitive to changes in surface radiative fluxes. Clouds influence shortwave radiation primarily through their high albedo and longwave by changing atmospheric emissivity determining the height (temperature) of layer highest emission. We review cloud properties affecting fluxes, estimate effect on top-of-atmosphere albedo, discuss response contribution decline during 21 st century predicted National Center for Atmospheric Research Community Climate System Model, version 3 (CCSM3). Over perennial ice, clouds decrease incoming flux at compared clear skies from zero winter ∼100 W m ―2 summer. On average over Ocean, retreat decreases reflected top atmosphere within same range all-sky conditions. In addition, warm increasing annual mean downwelling ∼40 . During century, CCSM3 predicts a drastic accompanied larger cover liquid water content, which increase both cooling warming effects surface. The caused partly compensated but not canceled stronger cooling. Warming near-surface an additional factor ultimate this model facilitating decline.