Convectively coupled gravity waves in the tropics: Why do most waves travel westward?

Observations are presented showing evidence of a strong, two-way coupling between tropical convection and zonally-propagating inertia-gravity wave disturbances with periods < 2 days and zonal scales < 1000 km. Many of these mesoscale wave disturbances can be classified as tropical squall line systems, including the fast-moving squall lines observed during GATE. To address the question of why westward-moving waves are preferred over eastward-moving, we describe results from explicit three-dimensional simulations of convection on an equatorial beta-plane.