Dynamic Efficiency of Heat and Momentum in Balanced Vortex Model

• Main Authors: Tien-Yiao Hsu, 許天耀
• Other Authors: 郭鴻基
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/64100930845412421190

碩士 === 國立臺灣大學 === 大氣科學研究所 === 103 === The observation data shows that the eyewall replacement cycle (ERC) results in different consequences. Kuo et al. (2009) found that approximately 28% of typhoons strengthen after the formation of secondary eyewall. Yang et al. (2013) developed four categories to classify the situations after the formation. They found these four categories exhibit different behaviors on intensity and routes on T-V diagram. "Dynamic efficiency of heat" eta (r; z; t)) developed by Hack and Schubert (1986) is to examine the effect of heating on the energy conversion rate (C) converting total potential energy (P) into total kinetic energy (K) They also pointed out that efficiencies vary under different vortex structures while total heating remains the same. In this study, we would apply dynamic efficiencies to examine the response of concentric eyewall cyclone Francis (2004). We find that the presence of outer eyewall enhances the efficiency response by approximately 50% to 400% through reducing Rossby length (lambda_R) while changing the heating ratio between inner and outer eyewalls from 1 : 2 to 2 : 1 enhances the efficiency by 100% to 600% (total heating is fixed). Apart from cylindrical coordinates, we also derive the dynamic efficiencies in quasi-geostrophic theory (Cartesian coordinates), Cartesian coordinates, spherical coordinates, and shallow water model for potentially application to other balance dynamics in different scales.