Convectively coupled waves in DARE simulations on an equatorial β-plane

Many mechanisms have been proposed to explain the equatorial convectively coupled waves. In this study, we will use equatorial β-plane experiments that explicitly simulate cumulus convection using the Diabatic Acceleration and REscaling (DARE) approach to investigate the mechanisms responsible for these waves. Our simulations reproduce the observed waves well in terms of their spectra and structures. Perturbation experiments further show that precipitation driven downdrafts and the modulation of lower-midtroposphere moisture by shallow convection are essential for these waves, while other factors, such as extratropical eddies, surface flux and radiation feedbacks, are not. A simple conceptual model will also be presented.