Large potential energy of gravity waves over a smooth surface with little convection: Simulation and observation

A numerical experiment is conducted using an Atmospheric General Circulation Model (AGCM) to investigate the presence of the large potential energy over a region of low topography and little convective activity, focusing on the tropical Atlantic region (10degreesE to 20degreesW, 0degrees to 20degreesS). It is found that gravity waves with a time period of 24 hours are excited near the Equator (similar to5degrees-15degreesN) in a region of large moist heating extending vertically up to 10-13 km. The gravity waves propagate upward from this region with a bias toward the south and are manifested as large energy fluxes in the cross equatorial region. Enhanced energy fluxes are therefore simulated at 20-30 km altitude over a region with no significant source of gravity waves, and are confirmed using Global Positioning Satellite/Meteorology (GPS/MET) experiment data.