Some Implications of the Mesoscale Circulations in Tropical Cloud Clusters for Large-Scale Dynamics and Climate

Abstract

Recent calculations suggest that mature cloud clusters produce a vertical distribution of diabatic beating with a sharp maximum near 400 mb and very weak heating below 600 mb. It is demonstrated that when such a vertical distribution of heating is applied to a linear steady-state model it results in simulated tropical east-west circulations which are in much better agreement with observations than those which are produced with a more conventional heating profile. In particular, the mature cloud cluster heating profile produces a Walker Circulation with its centers at the observed altitudes and with the observed westward tilt with height. It is suggested that the mature cloud cluster beating profile may provide the appropriate vertical distribution of tropical diabatic heating in many cases. since the presence or absence of mature cloud clusters is often the proximate cause of heating variations in the tropical atmosphere. Some further implications of this suggestion for large-scale dynamics and climate are discussed.