Analytic Representation of the Large-Scale Organization of Tropical Convection

The pivotal role of mesoscale organization on the large-scale coherence of tropical convection is represented by a nonlinear dynamical model. The general model consists of two interlocked systems: a mesoscale parameterization of organized convection and a two-layer model of large-scale equatorial dynamics. The lower-layer dynamics is Rossby gyre–like, whereas outflow from organized convection maintains the upper-layer circulation. The transports of zonal momentum in the vertical and meridional directions are key processes. An archetype of the general model, in spite of being brutally simplified, represents the convective organization, momentum transport, and equatorial superrotation realized by the cloud-resolving convection parameterization or superparameterization explicit approach developed by Grabowski. The mesoscale parameterization is an analytic equivalent of the cloud-system-resolving models used in this computational approach. Finally, issues in parameterizing convective organization are discussed.