Effects of dimensionality on simulated large-scale convective organization and coupled waves

Tropical multi-scale convective organization of the super-cluster kind and convectively coupled gravity waves are investigated by both two and three-dimensional cloud-system-resolving simulations. the experimental setup includes a constant-temperature ocean surface,constant and horizontally-uniform radiative cooling in the troposphere,and a uniform easterly background wind. the objective of this study is to quantify the impacts of dimensionality on the simulated large-scale convective patterns and associated gravity waves. eastward propagating large-scale coherent precipitating convection occurs regardless of the spatial dimension. the convective organization has a horizontal wavenumber-one structure in the computational domain and travels at about 1317 m s -1 relative to the ground,equivalent to 19-23 m s -1 relative to the environmental flow. however,the convectively-induced wave signature is much weaker in three dimensions than in two dimensions,as well as a faster translation and a smaller tilt of the vertical. moreover,a two-dimensional framework generates additional organizational modes compared to the three-dimensional results,including a fast westward-moving system with a mean-flow-relative speed comparable to the eastward-moving wavenumber-1 counterpart and the quasi-stationary (relative to the background flow) higher wavenumber precipitating system. this does not necessarily imply that these additional modes are artifacts of two dimensionality. © 2012,meteorological society of japan.