This thesis investigates the interaction between slantwise convection and large scale marine cyclogenesis. The major aspects of the work are: (1) to understand the physics of convective-cyclogenetic interaction using a two layer primitive equation model with a parameterization for slantwise convection, (2) to perform numerous sensitivity experiments with a three layer model to test the robustness of the proposed interaction, and (3) to quantify the contribution of convection to marine cyclogenesis using a high resolution model simulation. / The major conclusions are: (a) The two and three layer models produce realistic explosive cyclones with a simple parameterization for slantwise convection. (b) The explosive deepening coincides with the formation of the "bent-back" warm front. (c) The frontogenetic calculations and quasi-Lagrangian heat and vorticity budget calculations performed with the two layer model indicate the following sequence of events: Convection leads to rapid warm frontogenesis through "tilting" and the formation of the bent-back warm front. The sudden surge of cold advection in the regions of the bent-back warm front then forces the upper level heights over the cyclone center to fall in a rather dramatic way. Increased upper level vorticity advection interacts with the low-level system leading to explosive cyclogenesis. (d) The sensitivity study performed with the three layer model indicates that the formation of the bent-back warm front and the proposed interaction are quite robust for a range of parameters. However, there are quantitative differences when the low-level cloud mass fraction, surface drag force, the air-sea thermodynamic disequilibrium, vertical shear and static stability are varied. Shallow convection is insignificant in affecting the dynamics of cyclogenesis. (e) The high resolution simulation reveals that the descending branch of the slantwise convection may be responsible for the formation of the dry slot over the cyclone center in the early stages. The stratification in both the warm and the bent-back warm fronts exhibits slantwise neutrality after the explosively deepening period. (f) The PV (Potential Vorticity) inversion technique indicates that convection contributes to marine cyclogenesis. The inverted wind fields show a small scale cyclonic vortex and the presence of cold advection in the bent-back warm frontal region. (g) The PV diagnostics further reveal that the cold advection in the bent-back warm front decreases the surface potential temperature anoma
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.41528 |
| Date | January 1994 |
| Creators | Balasubramanian, G. (Govindasamy) |
| 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: 001403730, proquestno: NN94577, Theses scanned by UMI/ProQuest. |
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