Abstract/Summary

Global climate models inadequately represent aspects of tropical convection; many studies that underpin the parametrisation of convection incorporate the interactive effects of largescale circulations using the Weak Temperature Gradient or Weak Pressure Gradient approximations. This thesis examines the thermodynamic consequences of these approximated circulations, in particular for the generation of mechanical work that they imply. It develops approximate analytical formulae for conversions from potential to kinetic energy by circulations generated by the Weak Temperature Gradient approximation and explores the energetic processes involved. Furthermore, a recently proposed isentropic analytical framework for the mechanical energy budget is extended and applied to results from two coupled cloud resolving models. This confirms that the use of the Weak Temperature Gradient approximation does not introduce any thermodynamic anomalies, and the results produced by the cloud resolving models provide confirmation of the analytical results derived earlier. Scaling arguments for the components of the mechanical energy budget are presented. The same technique is also applied to re-analysis data to show how the mechanical energy generated by circulations such as the Walker and Hadley circulations can be calculated from this data.