| The interactions between tropical convection and atmospheric waves are investigated in an idealized, i.e., two-dimensional (2D) and non-rotating, framework. The dissertation is made up of three parts. The first investigates the linear response of an initially motionless tropical atmosphere to a spatially and temporally localized deep convective heat source. Consistent with output from high-resolution numerical simulations, results show that the heat source tends to strongly excite gravity wave packets with phase speeds in the range 35–45 m s−1 and 16–20 m s−1 , and that the passage of the faster- (slower-) moving packets should tend to inhibit (favor) the development of additional deep convection.; Part II discusses a linear tropical wave model in which vertical structure is truncated to include just two vertical normal modes: a fast-moving (first internal) mode and a slow-moving (second internal) mode. Based on the notion that deep convective development is strongly inhibited by the effects of dry air entrainment, anomalies in deep convective heating are assumed to be directly proportional to anomalies in column-integrated moisture. The model predicts that large-scale convectively coupled gravity waves, with realistic phase speeds and vertical temperature structures, should spontaneously develop from random initial conditions, even in the absence of a mean flow. Stratiform and deep convective heating processes both play an important role in the instability.; In Part III, a vertical normal mode transform algorithm is used to analyze the structure and energetics of large-scale [O(1000 km)] convectively coupled gravity waves that spontaneously develop in a 2D cloud resolving model simulation of radiative convective equilibrium. Results show that the simulated waves primarily owe their existence to an unstable interaction between convection and modes with phase speeds in the range 16–18 m s−1 (i.e., third internal modes). Stratiform heating processes are found to play an important role in maintaining the energy of these modes, in agreement with stratiform instability theory. In contrast to this theory, however, deep convective heating processes also play an important role. |
