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On the Roles of Radiation and Low-Level Vorticity in Numerical Simulations of Tropical Cyclogenesis
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | On the Roles of Radiation and Low-Level Vorticity in Numerical Simulations of Tropical Cyclogenesis. |
| 개인저자 | Smith, Warren Paul, II. |
| 단체저자명 | University of Colorado at Boulder. Atmospheric and Oceanic Sciences. |
| 발행사항 | [S.l.]: University of Colorado at Boulder., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 124 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-05B. Dissertation Abstract International |
| ISBN | 9781088324653 |
| 학위논문주기 | Thesis (Ph.D.)--University of Colorado at Boulder, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-05, Section: B.
Advisor: Nicholls, Melville. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Before a hurricane forms, a process known as tropical cyclogenesis must occur during which a tropical disturbance transforms into a tropical depression. In order to further understand how and when hurricanes will form, we must start by examining the processes that lead to tropical cyclogenesis. This dissertation employs numerical modeling techniques to highlight the roles that both low-level vorticity and longwave and shortwave radiation play in this transformation.Recent numerical modeling and observational studies indicate the importance of vortical hot towers (VHTs) in tropical cyclogenesis. It has recently been recognized that convective-scale downdraft outflows that form within VHTs also preferentially develop positive vertical vorticity around their edges which is considerably larger in magnitude than ambient values. During a numerical simulation of tropical cyclogenesis it is found that particularly strong small-scale low-level convectively-induced positive vertical vorticity anomalies (herein termed ``LCVAs'') occasionally form as convection acts on the enhanced vorticity at the edges of cold pools. The LCVAs studied are considerably deeper than the vorticity produced at the edges of VHT cold pool outflows, and their evolution is associated with persistent convection and vortex merger events which act to sustain them. This dissertation highlights the formation and evolution of two representative LCVAs and discusses the environmental parameters which eventually become favorable for one LCVA to reach the center of a larger-scale circulation as tropical cyclogenesis occurs.Recent literature also indicates the importance of longwave and shortwave radiation in TCG. Herein we examine the sensitivity of TCG to radiation in both idealized simulations for different initial vortex strengths, and in a case study framework of Atlantic Hurricane Matthew (2016) to highlight when during tropical cyclogenesis radiation is most important. It is shown that all else equal, a stronger initial vortex reduces the impact that radiation has on accelerating tropical cyclogenesis. In both modeling frameworks we find that radiation's primary role is to moisten the core of a disturbance, and after sufficient moistening occurs over a deep layer and the winds are sufficiently strong at the surface, radiation no longer plays as significant a role in tropical cyclogenesis. |
| 일반주제명 | Atmospheric sciences. Meteorology. Vortices. Radiation. Cyclones. |
| 언어 | 영어 |
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