Despite the fact that spiral rainbands have long been detected in radar observations, many aspects of their dynamics and their role in hurricanes still remain unresolved. In this thesis, the high-resolution PSU-NCAR nonhydrostatic mesoscale model (MM5) is used to perform three numerical simulations, namely, the control run, the dry run and the landfall simulation. The dynamics of inner spiral rainbands formed in the simulated hurricanes are studied. / It is shown that the interaction of low-level potential vorticity (PV) anomalies with boundary layer friction and the strong coupling of the PV band and the cloud band give rise to the inner spiral rainbands. The propagation properties of the PV bands are analyzed and found to be consistent with predictions of vortex Rossby wave theory. Empirical normal mode method is further applied to separate the vortex Rossby waves from the gravity waves. The former dominates the latter in terms of wave activities. The radial and vertical propagation and the associated eddy momentum and eddy heat fluxes of vortex Rossby waves are studied using the Eliassen-Palm (EP) flux. The wave-mean-flow interaction indicated by the divergence of the EP flux shows significant effects on the intensification of the hurricanes. / While diabatic heating tends to maintain a ring structure of PV by continually generating high PV in the eyewall, the vortex Rossby waves tend to redistribute the PV in the ring and to increase the inner-core PV. When diabatic heating is suppressed in the dry run and in the landfall simulation, the PV ring evolves to monopolar structure. The dynamical properties of the inner spiral rainbands and their roles on the intensity then vary as a response to the evolving mean PV structure of the hurricane. Nevertheless, the total effect of the asymmetric diabatic heating and the vortex Rossby waves tends to counteract the effect of the mean circulation.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.82843 |
| Date | January 2002 |
| Creators | Chen, Yongsheng, 1973- |
| Contributors | Yau, M. K. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Atmospheric and Oceanic Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001985149, proquestno: AAINQ88438, Theses scanned by UMI/ProQuest. |
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