This collaborative project will employ models with explicit convection to study Intertropical Convergence Zones (ITCZ) over the oceans, their interactions with tropical waves, and the dependence of both on convective and mesoscale processes. The primary modeling tool will be the Weather Research and Forecast (WRF) system, which has been augmented to run either as a high-resolution nested tropical channel or as a lower-resolution model with a cloud-resolving model used as a "superparameterization" for convection. This unique model framework allows side-by-side comparisons of simulated ITCZs and convectively coupled waves using standard convection parameterizations, superparameterization, or cloud-resolving horizontal resolution. A suite of idealized cloud-resolving experiments will be performed to test the hypothesis that horizontal mixing by eddies tends to make the ITCZ broader and weaker than it would be in their absence.
Convection-related tropical biases are a major source of error and uncertainty in global atmosphere models, so advances in understanding in this area should lead to improvements in a wide array of weather and climate applications. The project will support the education and training of an atmospheric sciences graduate student. The superparameterized version of the WRF model will eventually be made available to researchers in the broader atmospheric science community. Thus the broader impacts are substantial.
