Examples of Mechanisms for Negative Cloud Feedback of Stratocumulus and Stratus in Cloud Parameterizations

抄録

Mechanisms of cloud feedback for marine boundary layer clouds in GCMs (General Circulation Models) to the sea surface temperature increase, which can depend on parameterization, were investigated using single column model version of a GCM with two different low cloud schemes.
Both schemes showed negative cloud feedbacks and they were attributed to the increase of the liquid water path (LWP) with the future climate forcing for stratocumulus and stratus. The mechanisms of the LWP increase in the two schemes were investigated respectively through simple numerical experiments. The experimental results imply that in the first scheme, the increase of saturation specific humidity due to the temperature increase in the future climate forcing contributes to the negative cloud feedback through the parameterization determining in-cloud cloud water content (CWC). The results also imply that the increase of latent heat flux in the future climate contributes to increased LWP and hence negative cloud feedback in the other scheme.