Finding Energy Pathways from a Tropical Energy Bubble to a Mid-Latitude Jet Using Wave Activity Flux Vectors

An energy bubble containing large amounts of potential energy stored in the upper troposphere is a common feature to the tropics. This energy is supplied by convection in the tropics, some of which is tied to tropical cyclones. Pieces of this bubble break off from the tropics intermittently, moving poleward and providing energy to the mid-latitude wave train. This energy manifests itself as enhanced jets (kinetic energy) and amplified troughs and ridges (potential energy), features that have a major effect on weather conditions at the surface.

A metric that can be used to describe the conversion of energy from reservoirs of stored potential energy to atmospheric waves is developed in the paper "A Formulation of Three-Dimensional Residual Mean Flow Applicable Both to Inertia–Gravity Waves and to Rossby Waves" by Kinoshita and Sato (2013). Termed "Wave Activity Flux (WAF)", this metric is used to track the movement of available potential energy from the tropics into the mid-latitude wave train and finally through the wave train. Tracking the WAF provides insights into the energy sources for jet streak development and the phenomenon of extratropical wave development downstream of tropical events. An analysis of the connection between Hurricane Michelle and a strong Algerian cyclone in November 2001 is used as an example of the effects of this energy transfer.