Climate Change and Cloud Feedback: The Possible Radiative Effects of Latitudinal Redistribution

Abstract

The sensitivity of outgoing longwave flux to changes in cloud cover (∂F/∂A_c) as defined by Cess (1976) must be evaluated carefully to avoid discrepancies arising from the interchange of averaging conventions. In a recent zonal atmospheric model experiment the global value of ∂F/∂A_c was different in sign than in other calculations. This difference in behavior was traced to a latitudinal redistribution of cloud amount and height that occurred in the doubled CO₂ experiment. However, when ∂F/∂A_c was evaluated at individual latitudes and then weighted globally, the value of this parameter was consistent with those found by Cess (1976) and Budyko (1974).