UC Berkeley

Moist convective clouds play a key role in the earth's energy and water cycles, but their turbulent and localized nature makes it difficult to study how they interact with the large-scale atmospheric circulation. In this dissertation, we study the interaction between convection and the large-scale tropical atmosphere in two ways. First, we develop simple analytical models for how convection interacts with large-scale circulations in the tropical atmosphere. These models are primarily based on a traditional-but-crude approximation of gravity wave dynamics, in which the tropopause is assumed to be a rigid lid. We test these models in cloud-resolving numerical simulations of a small patch of tropical atmosphere and determine that some of these methods pass a simple test of self-consistency, but are far from perfect.

Alternately, we take a more sophisticated analytical approach-- instead of using the traditional rigid lid model of the tropical atmosphere, we derive novel analytical solutions for pulses of buoyancy (a crude representation of the effects of convective clouds) in an atmosphere with both a troposphere and a stratosphere. This construction allows wave energy to realistically radiate out of the troposphere. We find that allowing wave energy to radiate out of the troposphere causes buoyancy anomalies in the troposphere to decay on timescales of hours to days, in stark contrast to the rigid lid model, which predicts that buoyancy anomalies persist forever in the absence of dissipation.