Modeling the interaction between cumulus convection and linear waves in a limited domain cloud system resolving model

A limited domain cloud system-resolving model (CSRM) is used to simulate the interaction between cumulus convection and 2-dimensional linear gravity waves, a single horizontal wavenumber a time. For a single horizontal wavenumber, soundings obtained from horizontal averages of the CSRM domain allow us to evolve the large-scale wave equation and thereby model its interaction with cumulus convection. It is shown that convectively coupled waves with phase speeds of 11-13m/s can develop spontaneously in such simulations. The waves that develop are weaker at long (> ~10000km) and short wavelengths (~2000km), although evidence for the latter is less clear. The simulated wave structures are found to change systematically with the horizontal wavelength, and at horizontal wavelengths of 2000-3000km they exhibit many of the basic features of the observed 2-day waves. The simulated convectively coupled waves develop without feedbacks from radiative processes, surface fluxes, or wave radiation into the stratosphere, but vanish when moisture advection by the large-scale waves is disabled. Besides being a useful tool for studying wave-convection interaction, the present approach also represents a useful framework for testing the ability of coarse-resolution CSRMs and Single Column Models in simulating convectively coupled waves.