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A Search for Thermospheric Composition Perturbations Due to Vertical Winds

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A Search for Thermospheric Composition Perturbations Due to Vertical Winds A Search For Thermospheric Composition Perturbations Due To Vertical Winds Item Type Thesis Authors Krynicki, Matthew P. Download date 10/10/2021 01:22:59 Link to Item http://hdl.handle.net/11122/8895 A SEARCH FOR THERMOSPHERIC COMPOSITION PERTURBATIONS DUE TO VERTICAL WINDS A THESIS Presented to the Faculty of the University of Alaska Fairbanks in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY By Matthew P. Krynicki, B.S. Fairbanks, Alaska May 2006 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 3229738 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. ® UMI UMI Microform 3229738 Copyright 2006 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. A SEARCH FOR THERMOSPHERIC COMPOSITION PERTURBATIONS DUE TO VERTICAL WINDS By Matthew P. Krynicki RECOMMENDED: Advisory Committee Chair \Y L a Ccu>.CV) Physics Department Head APPROVED: Dean, College of Natural Science and Mathematics Dean of the Graduate School Date Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Abstract The thermosphere is generally in hydrostatic equilibrium, with winds blowing horizontally along stratified constant-pressure surfaces, driven by the dayside-to- nightside pressure gradient. A marked change in this paradigm resulted after Spencer et al. [1976] reported vertical wind measurements of 80 m-s -1 from analyses of AE-C satellite data. It is now established that the thermosphere routinely supports large- magnitude (~30-150 m-s_1) vertical winds at auroral latitudes. These vertical winds represent significant departure from hydrostatic and diffusive equilibrium, altering locally—and potentially globally—the thermosphere’s and ionosphere’s composition, chemistry, thermodynamics and energy budget. Because of their localized nature, large- magnitude vertical wind effects are not entirely known. This thesis presents ground-based Fabry-Perot Spectrometer OI(630.0)-nm observations of upper-thermospheric vertical winds obtained at Inuvik, NT, Canada and Poker Flat, AK. The wind measurements are compared with vertical displacement estimates at ~ 104 km2 horizontal spatial scales determined from a new modification to the electron transport code of Lummerzheim and Lilensten [1994] as applied to FUV- wavelength observations by POLAR spacecraft’s Ultraviolet Imager [Torr et al., 1995]. The modification, referred to as the column shift, simulates vertical wind effects such as neutral transport and disruption of diffusive equilibrium by vertically displacing the Hedin [1991] MSIS-90 [O2MN2] and [ 0 ]/([N2]+[0 2 ]) mixing ratios and subsequently redistributing the O, O 2, and N 2 densities used in the transport code. Column shift estimates are inferred from comparisons of UVI OI(135.6)-nm auroral observations to their corresponding modeled emission. The modeled OI(135.6)-nm brightness is determined from the modeled thermospheric response to electron precipitation and estimations of the energy flux and characteristic energy of the precipitation, which are inferred from UVI-observed Lyman-Birge-Hopfield N 2 emissions in two wavelength ranges. Two-dimensional column shift maps identify the spatial morphology of thermospheric composition perturbations associated with auroral forms relative to the model thermosphere. Case-study examples and statistical analyses of the column shift Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. iv data sets indicate that column shifts can be attributed to vertical winds. Unanticipated limitations associated with modeling of the OI(135.6)-nm auroral emission make absolute column shift estimates indeterminate. Insufficient knowledge of thermospheric air-parcel time histories hinders interpretations of point-to-point time series comparisons between column shifts and vertical winds. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. V Table of Contents Page Signature Page i Title Page ii Abstract iii Table of Contents v List of Figures viii List of Tables xiii List of Appendices xiv Acknowledgments xv Chapter 1 Introduction to the Thermosphere 1.1 Vertical Winds in the Thermosphere 1 1.1.1 Horizontal Winds in the Thermosphere due to Solar Radiative Input 1 1.1.2 Hydrostatic and Diffusive Equilibrium 2 1.1.3 Barometric Motion of the Thermosphere 4 1.1.4 Global-scale Divergence in the Thermosphere 4 1.1.5 Departure from Equilibrium Conditions 6 1.1.6 The Thermosphere’s Global-scale Horizontal Wind System 7 1.1.7 Vertical Winds in the High-latitude Thermosphere 10 1.2 The Thermosphere’s Composition 19 1.2.1 Structure and Composition, Basic Chemisty and Energetics of the Thermosphere and Ionosphere 19 1.2.2 Diffusion and Diffusive Equilibrium in the Thermosphere 30 1.3 A Search for Thermospheric Composition Perturbations due to Vertical Winds: Comparing Auroral Observations to Model Predictions 36 Chapter 2 Instrumentation 2.1 Introduction to Fabry-Perot Spectroscopy 52 2.2 The Inuvik, NT, Canada Fabry-Perot Spectrometer 53 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. v i 2.3 Inferring Thermospheric Composition Perturbations from Observations of the Airglow and Aurora 65 2.4 A Brief History of Satellite Imaging 68 2.5 The Global Geospace POLAR Spacecraft Ultraviolet Imager (UVI) 70 Chapter 3 Data Acquisition, Analysis and Observations 3.1 Fabry-Perot Observations ofUpper-Thermospheric Vertical Winds at Inuvik 81 3.1.1 Vertical Winds: General Considerations 81 3.1.1.1 The Zero Doppler-shift Reference 81 3.1.1.2 Scattering 85 3.1.2 The Doppler-shifted Atomic Oxygen (01) 1630.0-nm Emission 88 3.1.3 Generating One-Dimensional Spectra from Inuvik FPS Fringe Images 91 3.1.4 Correcting for Etalon Drift and the Inuvik Vertical Wind Time Series 109 3.2 Characterization of Precipitating Electrons 147 3.2.1 Airglow Removal from the UVI LBH-S, LBH-L and 01(135.6)-nm Auroral Observations 148 3.2.2 Inferring Energy Flux and Characteristic Energy from UVI LBH-L and LBH-S Auroral Observations 153 3.2.3 Modeling the 01(135.6)-nm Auroral Emission 169 3.2.4 Vertical Displacement and Disruption of Diffusive Equilibrium: The Column Shift Parameter Modification to the MSIS-90 Model Thermosphere Density Structure 174 Chapter 4 Analysis and Discussion of Observations and Results 4.1 Comparison of the Time Series of Vertical Wind Measurements to Column Shift Estimates 198 4.2 Column Shift and Vertical Wind Distributions and Discrepencies between the Observed and Modeled OI( 13 5. 6)-nm Auroral Emission 250 Chapter 5 Discussion, Conclusions and Future Work 5.1 Discussion and General Conclusions 282 5.2 Summary and Future Work 290 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. v ii 5.2.1 The Inuvik Fabry-Perot Spectrometer 290 5.2.2 Comparing the Modeled OI(135.6)-nm Brightness to Observations: The Column Shift Parameter 291 References 294 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. List of Figures Fig. 1.1 E- and F-region temperature structure and horizontal neutral vector winds. 11 Fig. 1.2 Constituents of the thermosphere and ionosphere and their densities. 23 Fig. 1.3 Electron density of the ionosphere. 24 Fig. 1.4 Vertical winds, N 2 density, and ion temperature in the upper thermosphere. 39 Fig. 2.1 Schematic representation of the major components of an imaging FPS. 55 Fig. 2.2 Block diagram indicating the major components of the Inuvik FPS. 56 Fig. 2.3 Modulated laser light from the Fabry-Perot etalon at Inuvik, the retrieved instrument function, and the Airy formula fit. 62 Fig. 2.4 Schematic representation of the 8 ° FOV o f the UVI. 72 Fig. 2.5 The POLAR spacecraft orbital trajectory on February 28, 2000 from 0000-1800 UT. 74 Fig. 2.6 FUV spectrum and the five filter passbands of the UVI instrument. 77 Fig. 2.7 Absorption cross section for molecular oxygen. 79 Fig. 3.1 Visualizing etalon transmission distortions. 94 Fig. 3.2 Fitted virtual etalon fringes overlayed on a real laser fringe pattern. 95 Fig. 3.3 FPS observation of the OI(630.0)-nm airglow and auroral emission obtained at Inuvik. 97 Fig. 3.4 The etalon’s instrument function on January 3, 2001. 97 Fig. 3.5 Sampled 1-D spectrum inferred from the 01(630.0)-nm sky image shown in Figure 3.3. 98 Fig. 3.6 Sampled 1-D spectrum inferred from a OI(630.0)-nm sky image obtained on the night of December 22, 2000. 101 Fig. 3.7 Upper-thermospheric vertical wind measurements from December 25, 1998 obtained with the CRL-FPS and the SDI-FPS at Poker Flat, AK. 108 Fig. 3.8 Etalon drift-correction analysis on the night of Jan 3, 2001. 117-119 Fig. 3.9 Upper-thermospheric vertical wind speeds on the night of Jan 3, 2001. 122 Fig. 3.10 Etalon drift-correction analysis on the night of Dec 9, 2000. 123-124 Fig. 3.11 Upper-thermospheric vertical wind speeds on the night o f Dec 9, 2000. 126 Fig. 3.12 Etalon drift-correction analysis on the night of Dec 22, 2000. 127-128 Fig.
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