Evaluation of a Heuristic Model for Tropical Cyclone Resilience
Abstract
This work examines the applicability of a previously-postulated heuristic model for the temporal evolution of the small-amplitude tilt of a tropical cyclone-like vortex under vertical-shear forcing for both a dry and cloudy atmosphere. The heuristic model hinges on the existence of a quasi-discrete vortex-Rossby wave and its ability to represent the coherent precession and tilt-decay of a stable vortex in the free-alignment problem. Linearized numerical solutions for a dry and cloudy vortex confirm the model predictions that an increase in the magnitude of the radial potential vorticity (PV) gradient within the vortex skirt surrounding the core yields a more rapid evolution of a sheared vortex towards the equilibrium, left-of-shear tilt configuration. However, in the moist-neutral limit, in which the effective static stability vanishes in rising and sinking regions, the heuristic model yields a poor approximation to the simulated vortex core evolution, but a left-of-shear tilt of the near-core vortex, radially beyond the heating region, remains the preferred long-time solution. Within the near-core skirt the PV perturbation generated by vertical shearing exhibits continuous-spectrum type vortex-Rossby waves, features that are not captured by the heuristic model. Nevertheless, the heuristic model continues to predict the rapid vertical alignment and equilibrium, left-of-shear tilt configuration of the simulated near-core vortex in the moist-neutral limit.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 26, 2015
- Accession Number
- ADA623745
Entities
People
- Michael T. Montgomery
- Paul D. Reasor
Organizations
- Naval Postgraduate School