Radiative damping rates and their relations to climate sensitivity

The radiative damping of climatological variations in surface temperature is analyzed based on relationships between surface temperature and top-of-atmosphere radiative fluxes. The observed damping rates are generally consistent with positive radiative feedbacks over the tropical oceans, in agreement with climate model simulations. However, the inferred feedback parameters show substantial variations depending on time period and the type of model simulation. Conversely, when analyzed at global-mean spatial scales, the climate model simulations exhibit more consistent radiative damping rates, suggesting that the tropical ocean is too small of a domain for robust estimates of radiative damping. Moreover, it is found that the model-simulated values of global-mean radiative damping rates deduced from interannual variability are modestly correlated to the climate sensitivity of the model in response to increasing carbon dioxide.