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Global-Scale, Nonlinearly-Generated Waves in the Space-Atmosphere Interaction Region

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Global-Scale, Nonlinearly-Generated Waves in the Space-Atmosphere Interaction Region Global-Scale, Nonlinearly-Generated Waves in the Space-Atmosphere Interaction Region by Vu Anh Nguyen B.S., University of Colorado, 2011 M.S., University of Colorado, 2011 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Aerospace Engineering Sciences 2016 This thesis entitled: Global-Scale, Nonlinearly-Generated Waves in the Space-Atmosphere Interaction Region written by Vu Anh Nguyen has been approved for the Department of Aerospace Engineering Sciences Prof. Scott E. Palo Dr. Ruth S. Lieberman Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. iii Nguyen, Vu Anh (Ph.D., Aerospace Engineering Sciences) Global-Scale, Nonlinearly-Generated Waves in the Space-Atmosphere Interaction Region Thesis directed by Prof. Scott E. Palo Understanding of the space-atmosphere interaction region spanning from 60 km to 500 km altitude is becoming increasingly important for satellite operations. Significant variability in this region is induced by global-scale atmospheric tides and planetary waves generated in the lower atmosphere, which can vertically propagate with increasing amplitude. Past studies have suggested that these global scale waves may nonlinearly interact to produce additional secondary waves and thus, introduce further variability in the region This dissertation investigates the secondary waves that are produced during a nonlinear interaction between the quasi two-day wave and the migrating diurnal tide, two of the largest global- scale waves in the upper atmosphere. Theoretically, this nonlinear interaction should produce the 16hrW4 and 2dayE2 secondary waves. The main goal is to characterize the secondary wave forcing region and understand how this relates to their manifestation throughout the atmosphere. The first portion of this dissertation applies the Fast Fourier Synoptic Mapping technique to present new observational evidence of secondary waves in the mesosphere-lower thermosphere region. The results demonstrate that the secondary waves are significant at altitudes above 80 km, and do not necessarily coincide with the regions where the interacting primary waves are largest. In order to further understand the secondary wave generation process, numerical experiments with a linearized tidal model are conducted. First, short-term primary wave estimates are extracted from the NOGAPS-ALPHA reanalysis model and are utilized to derive observationally-based non- linear forcing quantities for the 16hrW4 and 2dayE2 secondary waves. The nonlinear forcing values are then implemented in a linear tidal model that is modified to compute secondary wave responses from the surface to the upper thermosphere. Numerical experimental results demonstrate that the magnitude of the secondary wave response in the mesosphere-lower thermosphere region is depen- iv dent on factors such as the spatial distribution and location of the forcing, and the secondary wave frequency and vertical wavelength. Additional experiments simulating the interaction between the quasi two-day wave and the migrating semidiurnal tide suggest that certain secondary waves may be able to propagate far into the thermosphere and hence, introduce significant variability within the space-atmosphere interaction region. Dedication To my parents, for your unconditional guidance, support and love. vi Acknowledgements The completion of this dissertation would not have been possible without the guidance and support of several individuals. Some of these names are listed here, but are by no means a complete list. I wish to thank my advisor Prof. Scott Palo for giving me the opportunity to conduct research under his wing even though I first walked into his office six years ago without ever hearing the word \atmospheric tide" before. I am grateful for his timely advice which has allowed me to develop into a critically-thinking, independent researcher. I also wish to thank Dr. Ruth Lieberman who saw enough potential in me to agree to support my Ph.D. This dissertation would not have been possible without her mentoring and knowledge of middle/upper atmospheric dynamics. I am appreciative of Prof. Jeff Forbes who kindly granted me permission to modify the GSWM for this study. His class on atmospheric tides and planetary waves was also one of the most valuable classes that I have taken at CU. Additionally, I would like to thank my other committee members, Dr. Han-li Liu and Prof. John Cassano, for the educational discussions both inside and outside of our committee meetings. I have also stood on the shoulders of many other experts in the field to be where I am today. I would like to specifically acknowledge Dr. Loren Chang for his insight and support during my summer stint at National Central University in Taiwan. I am also appreciative of all the students and other faculty members who I've been fortunate to interact with over the last 10 years. To my professors, thank you for being an inspiration to me and helping the CU Aerospace Engineering Department become a world-class environment for education and research. To all of my past and current colleagues who I've been fortunate enough vii to connect with, thank you for making my CU experience such a wonderful and unforgettable one. I wish everyone here the same joy that you have given me over the years. This work was supported by JPL subcontract 1483557 through GATS, Inc. and the JPL Strategic University Research Partners (SURP) award. viii Contents Chapter 1 INTRODUCTION 1 1.1 The Space-Atmosphere Interaction Region . 1 1.2 Atmospheric Tides and Planetary Waves . 4 1.3 Limited Understanding of Nonlinearly Generated Waves . 7 1.4 Objectives . 9 2 BACKGROUND 12 2.1 Classical Tidal Theory . 12 2.1.1 Mathematical Formulation . 12 2.1.2 Tidal Sources and Theory Limitations . 19 2.2 Migrating Diurnal Tide . 20 2.3 Planetary Waves and the Quasi Two-Day Wave . 25 2.4 Secondary Waves from Quasi Two-Day Wave and Migrating Diurnal Tide Interaction 28 2.5 Potential Impacts of Nonlinearly Generated Waves . 32 3 METHODOLOGY & DATA SOURCES 38 3.1 Methodology . 38 3.2 Data Sources . 40 3.2.1 Satellite Instruments . 40 3.2.2 NOGAPS Reanalysis . 43 ix 3.2.3 Global Scale Wave Model . 43 4 SECONDARY WAVES FROM OBSERVATIONS 47 4.1 Technique for Extracting Secondary Wave Evidence . 47 4.1.1 Estimating Waves from Satellite Instruments . 47 4.1.2 Fast Fourier Synoptic Mapping Method . 51 4.2 Quasi Two-Day Wave and Secondary Waves from SABER Observations . 57 4.3 Secondary Wave Comparison to NOGAPS-ALPHA . 67 5 COMPUTATION OF SECONDARY WAVE FORCING 72 5.1 Origin of Nonlinear Forcing . 72 5.2 Primary Wave Estimates . 73 5.2.1 Estimating from Only Observations . 73 5.2.2 Chosen Method: NOGAPS-ALPHA . 90 5.3 Nonlinear Forcing Results . 97 6 SECONDARY WAVE RESPONSES 107 6.1 Secondary Wave Response in Zero-Wind Background . 107 6.2 Dissipation Effects on Secondary Wave Hough Modes . 113 6.3 Efficient Projection of Forcing on Propagating Hough Modes . 118 6.4 Importance of Altitude Location . 123 6.5 Impact of Primary Wave Phase on Secondary Wave Response . 128 6.6 Secondary Wave Response with Background Winds . 128 6.7 Shape Function . 135 6.8 Mean Wind Effects on the Nonlinear Forcing Projection Responses . 137 6.9 Time Evolution . 142 6.10 Comparison to NOGAPS . 147 x 7 NONLINEAR INTERACTION BETWEEN QUASI-TWO DAY WAVE AND MIGRATING SEMIDIURNAL TIDE 151 7.1 Introduction . 151 7.2 SW2-2dayW3 Amplitudes . 152 7.3 Nonlinear Forcing . 158 7.4 Secondary Wave Responses . 160 8 CONCLUSIONS 173 8.1 Summary . 173 8.2 Discussion and Future Work . 176 Bibliography 178 Appendix A GLOSSARY 187 B WAVE NOMENCLATURE 188 C DERIVATION OF NONLINEAR FORCING 189 D FAST FOURIER SYNOPTIC MAPPING DETAILS 195 D.1 FFSM Procedure . 195 D.2 Additional Aliasing Tests for Least Squares and FFSM methods . 199 E SUPPLEMENTAL FIGURES: PRIMARY WAVES AND NONLINEAR FORCING 202 F SUPPLEMENTAL FIGURES: SECONDARY WAVES COMPUTED FROM THE LINEAR TIDAL MODEL 219 xi Figures Figure 1.1 Atmosphere-space coupling by waves . 3 1.2 Vertical propagation of migrating diurnal tide in observations . 5 1.3 Temperature perturbations seen in TIMED/SABER . 8 1.4 Forcing and generation of secondary waves . 11 2.1 Migrating diurnal tide hough modes and expansion functions . 22 2.2 Diurnal (1, 1) Hough mode in an eastward jet at 40◦ . 24 2.3 Daily estimates of the DW1 for 2009 at equator and 79 km . 25 2.4 QTDW geopotential height and circulation at 80 km . 27 2.5 Fourier power spectra of zonal wind fields in 2-day wave TIMEGCM experiment . 33 2.6 Planetary wave modulation of total electron content . 34 2.7 Response of the thermosphere to a varying eddy diffusion coefficient in the TIE-GCM 36 3.1 SABER and MLS solar local time coverage . 42 3.2 NOGAPS-ALPHA 2-day wave comparison with MF radar . 44 4.1 MLS and SABER time/longitude sampling over multiple days . 49 4.2 MLS and SABER time/longitude sampling over multiple days in R-S coordinates . 52 4.3 Asynoptic Nyquist rectangle . 53 4.4 FFSM reconstruction of 2dayW3 signal . 54 4.5 Least squares method and FFSM aliasing from 2dayW3 to 2dayE2 . 56 xii 4.6 FFSM reconstruction of 16hrW4 signal . 57 4.7 Evidence of 2dayE2 waves during 2dayW3 events . 58 4.8 Time evolution of 2dayW3 amplitude latitude structure for selected years . 61 4.9 2dayW3 latitude-altitude amplitude structure in temperature for selected years . 62 4.10 2dayW3 latitude-altitude amplitude structure in geopotential height for selected years 63 4.11 2dayW3 phase progression with altitude at 30◦S latitude .
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