Understanding the Interaction between Convection and Large-scale Circulation Using Cloud Resolving Model Simulations

Abstract:

The interaction between convection and large-scale circulation is a fundamental issue in global climate modeling. Many biases in GCMs, including ITCZ, MJO or tropical climate state in general, can be tracked to the lack of sufficient understanding of this interaction. Dynamicists view convection as a heating source for atmospheric circulation while modelers view convection as a result of large-scale forcing. In this study, we examine the relationships between convection and the circulation fields for different scales. We use cloud resolving model simulations of tropical convective systems from the ARM TWP-ICE field experiment to create domain averages representing different spatial scales. We find that some convective parameterization closures fare better than others in representing the relationships between convection and the circulation fields. The implication of this for improving convective parameterization and reducing GCM model biases will be discussed.