The generation of kinetic energy in tropical cyclones revisited

Abstract

Many previous diagnoses of the global kinetic energy for a tropical cyclone have given prominence to a global integral of a pressure-work term in the generation of kinetic energy. However, in his erudite textbook of atmospheric and oceanic dynamics, Gill (1982) derives a form of the kinetic energy equation in which there is no such explicit source term. In this paper we revisit the interpretations of the generation of kinetic energy given previously in the light of Gill's analysis and compare the various interpretations, which are non-unique. Further, even though global energetics provide a constraint on the flow evolution, in the context of the kinetic energy equation, they conceal important aspects of energy generation and consumption, a finding that highlights the limitations of a global kinetic energy budget in revealing the underlying dynamics of tropical cyclones.

Contribution of mean and eddy momentum processes to tropical cyclone intensification

“…(2020), a way to think about the upper‐level outflow layer is to consider it as an expanding jet of air emanating from a mass and radial momentum source where the eyewall convection terminates (Ooyama, 1987). The outward expansion is resisted by a radially inward pressure gradient force (e.g., Smith et al ., 2018, figure 5c,d), recalling that the centrifugal force is always positive and the Coriolis force in the radial direction is positive as long as the tangential flow remains cyclonic. Because the induced pressure field extends vertically beyond just the outflow layer itself, one can expect a flow response vertically beyond the outflow layer as well.…”

Upper‐tropospheric inflow layers in tropical cyclones

“…Most notably, there was no mention of the possible existence and role of upper‐tropospheric inflow layers that are found to develop in numerous numerical model simulations of tropical cyclone intensification where the vertical resolution is sufficient (e.g., Rotunno and Emanuel 1987, figure 5c; Hausman et al ., 2006, figures 4b and 8b; Bui et al ., 2009, figure 6a; Persing et al ., 2013, figures 15a, 17a, and 18a; Bu et al ., 2014, figures 4a,b, 9a,b, 12, and 16; Smith et al ., 2014, figure 2c; Ohno and Satoh 2015, figure 2b; Fovell et al ., 2016, figures 11–21; Kieu et al ., 2016, figures 2b and 4; Heng et al ., 2017, figure 4c; Chen et al ., 2018, figure 14a,c; Smith et al ., 2018b, figure 2b,d). Most of these papers relate to the evolution of a tropical‐cyclone‐like vortex in the prototype problem for tropical cyclone intensification, which considers the evolution of a vortex on an f ‐plane in a quiescent environment, starting from an initially symmetric, moist, cloud‐free vortex over a warm ocean.…”

A Moist Available Potential Energy Budget for an Axisymmetric Tropical Cyclone

“…, Smith et al (2018); small sources or sinks of kinetic energy due to the elastic mass divergence term; changes in available elastic energy due to the heating correction term in the pressure equation; the frictional dissipation of kinetic energy; and the vertical buoyancy flux,…”