Tropical atmospheric waves play a major role in the variability and change of weather and climate in the tropics as well as in the globe. They also interact with other tropical systems
such as tropical cyclones (TCs) and El Niño-Southern Oscillation (ENSO). The improved understanding of the tropical waves, such as their origins, their spatiotemporal structures, and their
life cycles, can lead to better prediction of weather and climate change in the tropics as well as over many other areas of the globe. Most of the previous diagnoses of observed tropical
waves came from two categories: (1) case studies in which individual waves of particular types are examined, leading to scattered information of the spatiotemporal characteristics of these
waves; and (2) climatological studies using wavenumber-frequency domain analysis which is not able to identify spatiotemporal inhomogeneity of tropical waves. To fill the gap between these
two approaches, we use a recently developed spatiotemporally local analysis method, the multi-dimensional ensemble empirical mode decomposition (MEEMD) method, and known spatial wind
structures of different types of waves to systematically extract the evolution information of tropical waves over large temporal and spatial domains. Through further analysis of the extracted
wave events, the spatiotemporal inhomogeneity of tropical waves is characterized. In this study, as the very first step toward a comprehensive study, our focus is placed on mixed
Rossby-gravity (MRG) waves. The propagation characteristics, period, and horizontal (zonal and meridional) scale of MRG events detected in this study can match with both the theoretical
results and observational studies. There are 23 MRG events detected from the 3rd MEEMD component in the year 2002, among which most events occurred over the western Pacific Ocean and fewest
MRG events over the Indian Ocean. The phase velocity and meridional scale are largest over the Atlantic Ocean while smallest in the Indian Ocean. The locations and propagation characteristics
of MRG events show great spatiotemporal inhomogeneity. After the evolution of MRG events are obtained, they can be connected with TCs. A new hypothesis, which better matches the observation,
is proposed that the swelling and westward propagation of MRG wave pattern help the TCs moving westward and toward higher latitudes, which is necessary for TCs to develop at early
stage. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of
Science. / Fall Semester, 2014. / October 9, 2014. / Ensemble Empirical Mode Decomposition, Mixed Rossby-Gravity Waves, MRG evolution, Tropical Depressions / Includes bibliographical references. / Zhaohua Wu, Professor Directing Thesis; Mark Bourassa, Committee Member; Vasu Misra, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_253413 |
| Contributors | Sun, Jie (authoraut), Wu, Zhaohua (professor directing thesis), Bourassa, Mark A. (committee member), Misra, Vasubandhu, 1970- (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Earth, Ocean, and Atmospheric Science (degree granting department) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource (57 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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