Kinetic energy diagnostic studies of extratropical cyclones based on storm relative motion

The kinetic energy equations for earth and storm relative motions and their radial and tangential components are derived. The equations are used to estimate quasi-Lagrangian kinetic energy budgets of two extratropical cyclones representing different types of development, one with strong latent heat release, the other with little latent heat release. The intensification of the circulation during the evolution of both storms is uniquely identified by the kinetic energy of storm relative motion, while the kinetic energy of earth relative motion fails to make a unique identification. Decomposition of the storm relative kinetic energy budget into tangential and radial components allows the evolution of the storm's cyclonic circulation to be distinguished from kinetic energy advection and mass-momentum adjustment associated with the relative influence of the upstream and downstream jets.;Composite budgets are constructed from four storms. The results reveal a strong production of radial storm relative kinetic energy by baroclinic processes, a substantial portion of which is transformed to tangential storm relative kinetic energy through inertial processes. This source combines with inward kinetic energy transport to increase the cyclonic circulation against losses through frictional dissipation and outward ageostropic radial flow.;The relations between tangential storm relative kinetic energy and angular momentum are derived. During development accompanied by strong latent heat release, intensification of the cyclone's vortex occurs through a simultaneous increase of both angular momentum and tangential storm relative kinetic energy throughout the troposphere. Sources and sinks of storm relative tangential kinetic energy and angular momentum correspond closely with each other. The relationships between sources in the two budgets are interpreted through absolute angular momentum balance requirements in conjunction with the adjustment of the upper tropospheric circulation to lower tropospheric thermal advection and Eliassen's (1951) perspective on the forcing of the meridional mass circulation of vortices.