Influence of Topography on Tropical Cyclone Tracks - Idealized Simulations
| Autor: | Tsung-Han Li, 李宗翰 |
|---|---|
| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 Both observational and numerical studies have shown that tropical cyclones (TCs) tend to deflect when approaching or passing over a mesoscale mountain range. Observations, particularly those from the in-situ radars, have documented a number of typhoons experiencing track deflection near the east coast of Taiwan. In order to further assess the orographic influence on TC track deflection, more parameters and flow regimes are investigated in this study. A full-physics model (MM5) is utilized to construct a set of idealized experiments at 3-km horizontal resolution. In the control experiment, we simulate a westward-moving TC approaching a bell-shape terrain with 3-km maximum height. Different from the results of previous studies, the low-level northerly jet induced by the channeling effect in the western side of TC is not identified. Instead, it is shown that the mid-level wind magnitude is strengthened in the western side of TC, and is weakened in the eastern side of TC, contributing to the southward TC deflection. Further parameters describing the idealized vortex and mountain, including TC intensity (Vmax), translation speed (U), radius of maximum wind (R), initial position, incident angle, mountain height (h), x-direction mountain range (Lx), y-direction mountain range (Ly) and mountain shape, are fully examined. The results suggest that some parameters (such as the TC intensity, translation speed, mountain height and shape) are playing mportant roles in causing the track deflection. By analyzing the results of control experiment and sensitivity experiments, we find that the channeling effect would appear in some specific flow regime (such as TC approaching to the higher terrain or north part of the terrain). The idealized experiments from this study provide better physical insight into how TC movement is influenced by topography. Further researches are needed to investigate the key mechanisms leading to the topographic deflection of TC track. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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