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Life Cycle of Atmospheric Rivers over the North Pacific: Identification, Processes, and Intraseasonal Variability
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Life Cycle of Atmospheric Rivers over the North Pacific: Identification, Processes, and Intraseasonal Variability. |
| 개인저자 | Zhou, Yang. |
| 단체저자명 | State University of New York at Stony Brook. Marine and Atmospheric Science. |
| 발행사항 | [S.l.]: State University of New York at Stony Brook., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 105 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781687961624 |
| 학위논문주기 | Thesis (Ph.D.)--State University of New York at Stony Brook, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Kim, Hyemi. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Atmospheric rivers (ARs) are intensive poleward moisture transport that are essential for the global water cycle and regional hydrology. Frequent AR activity occurs over the North Pacific during boreal winter. The North Pacific ARs have significant socioeconomic impact on western North America because AR-induced precipitation can supply beneficial water resources or cause disastrous events like flooding. While previous studies have investigated different features of North Pacific ARs including structure, seasonality, and variability, the life cycle of AR events that shows the spatiotemporal evolution of AR remains poorly documentedly understood. The dissertation aims to better understand the life-cycle characteristic of AR events over the North Pacific, AR-associated dynamical processes and the intraseasonal variability of the life cycles of AR events.An object-based tracking algorithm is developed to identify an AR event and record its life-cycle characteristics including origin, termination, lifetime, intensity, propagation speed and direction, and the traveled distance. Most North Pacific AR events originate in the subtropics and terminate at higher latitudes over western North America. Longer-lived AR events can travel longer in distance and have stronger intensity than shorter-lived AR events. An accumulated AR intensity index is developed to summarize the overall impact of AR events over a given domain during a certain period.Using the tracking algorithm, the life-cycle characteristics of landfalling AR events over the US West Coast is further examined based on distinct origin locations (Northwest vs. Northeast Pacific). Landfalling AR events originating from the Northwest Pacific generally last longer and have stronger intensities than those from the Northeast Pacific. A persistent tripole pressure anomaly pattern over the North Pacific modulates the origin location and propagation direction of landfalling AR events. Landfalling AR events originating from the Northwest Pacific contribute approximately 25% of total winter precipitation over Washington and British Columbia, while those from the Northeast Pacific make to 30% of total winter precipitation over California. The tracking algorithm is further utilized to understand the modulation of AR life cycles by the Madden-Julian Oscillation (MJO) which is the dominant mode of tropical intraseasonal variability. As the MJO propagates from the Indian Ocean to the western Pacific, the origin frequency and propagation of AR events are modulated via the MJO-associated atmospheric circulation and moisture anomalies, in addition to mid-latitude circulation patterns. In particular, AR life cycles are strongly modulated by the MJO when enhanced convection is over the Indian Ocean (i.e. MJO phase 2-3) and western Pacific (i.e. phase 6-7). Global climate models (GCMs) simulates a realistic MJO-AR relationship despite biases in the MJO intensity and AR frequency. |
| 일반주제명 | Atmospheric sciences. |
| 언어 | 영어 |
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