approximating ambient d-region electron densities using dual-beam hf heating experiments at the ...

125 Pages·2013·30.24 MB·English

APPROXIMATING AMBIENT D-REGION ELECTRON DENSITIES USING DUAL-BEAM
HF HEATING EXPERIMENTS AT THE HIGH-FREQUENCY ACTIVE AURORAL
RESEARCH PROGRAM (HAARP)
By
DIVYA AGRAWAL
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
2013
⃝c 2013 Divya Agrawal
2
This dissertation is dedicated to my parents
Renu and Susheel
and to my husband
Alexander
3
ACKNOWLEDGMENTS
I would like to thank my advisor Dr. Robert Moore for providing me the wonderful
opportunity to perform this work and for his patience and guidance through the years. I
am particularly grateful to my committee members, Dr. Jenshan Lin, Dr. Martin Uman,
and Dr. Norman Fitz-Coy for their valuable comments and suggestions.
I extend special thanks to new and old friends at the ionospheric research lab,
especially Shuji Fujimaru who has provided me invaluable support and motivation,
Daniel Kotovsky for his valuable discussions, Michael Mitchell for building all the
hardware, and Neal Dupree for his expertise using the high performance computing
facility. I also want to thank the newest members of our group Brittany Finch for her
assistance in processing some data and Sydney Greene for being a true friend.
I would like to extend my appreciation to the administrative staff of the ECE
department. Shannon Chillingworth, our graduate student advisor has made my life
easier on so many levels, Stephenie Sparkman, Edwina McKay and Angela Petringelo
for effortlessly running the front office with a warm smile. Janet Holman, Erlinda Lane,
Kym Mason and Jennifer Freeman for making our travels and purchasing so much
easier and less stressful. I would like to also thank Ray McClure and Waleta Newman
for taking care of all our packages and shipments and Laurie Edvardsson for helping me
with printing and binding my dissertation. They have all enriched my graduate school
experience and been my pillar of support.
This research would not have been successful without the help of the crew from
Alaska. I would especially like to thank the owners of Chistochina B&B, Norma
and Doyle Traw for taking good care and checking on us and our receiver site. Jay
Scrimshaw and Dugh & Judy for minding our receiver sites at Oasis and Paradise
respectively. We were able to get phenomenal data from these receiver sites, which
has been extensively used in this research. I would also like to thank the HAARP crew,
Jay Scrimshaw, Marty Karjala and Stephen for providing the inexperienced Florida
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students with Alaskan weather gear and mentoring us on so many levels and sharing
their Alaskan experiences with us. In addition, I would like to thank the operators of
HAARP, Mike McCarrick, Helio Zwi and Dave Seafolk-Kopp who have accommodated
our last minute changes in transmission formats and have worked tirelessly on all the
campaigns. Last, but definitely not the least, I would like to thank Ed Kennedy and Lee
Synder for their contribution in running the campaigns and providing me support and
guidance in the chat room.
This work would not have been possible without the love and support of some of
my dear friends, Sendhil, Heera, Bharani, Jennifer Jackson, Erin Patrick, Laureen Ricks,
Anitra, Gayatri, Pareena, Atchar, Suresh. I of course can’t list all your names, but you
know who you are.
I am thankful to Aunty Pramila, Aunty Radha, Uncle Subarna, Uncle Tirtha, Asha
and Sheela for opening their home to me, for the delicious home cooked meals and for
loving and caring me like their own. I always looked forward to spending weekends and
holidays with them. My parents, Renu and Susheel although across the Atlantic, have
been my biggest strength through the years. Their phone calls and Skype calls would
brighten my day. I thank them from the bottom of my heart for their love, support and
commitment. I thank my brother Nikhil and his family for checking on me, advising and
supporting me. My in-laws, Don BK and Don˜ya Zoila, Carol and Johny for their love and
support. Lastly, my dear husband Alex for his love, support, guidance, motivation and
patience through the years. I am looking forward to our exciting journey together.
This work is supported by US Air Force grant FA9453-12-1-00246, DARPA contract
HR0011-09-C-0099, DARPA grant HR0011-10-1-0061, ONR grant #N000141010909,
and NSF grants AGS-0940248 and ANT-0944639 to the University of Florida.
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TABLE OF CONTENTS
page
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
LIST OF ABBREVIATIONS AND SYMBOLS . . . . . . . . . . . . . . . . . . . . . . 12
CHAPTER
ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.1 The Ionosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2 The D-Region Ionosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.3 Previous Efforts to Characterize the D-Region Ionosphere . . . . . . . . . 18
1.3.1 Rocket Sounding Techniques . . . . . . . . . . . . . . . . . . . . . 18
1.3.2 Incoherent Scatter Radar (ISR) . . . . . . . . . . . . . . . . . . . . 19
1.3.3 Ionosonde . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.3.4 Lightning as a Source for Remote Sensing . . . . . . . . . . . . . . 20
1.3.5 HF Cross-Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . 21
1.4 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
1.5 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.6 Scientific Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2 DUAL-BEAM ELF/VLF WAVE GENERATION: MODEL IMPLEMENTATION . . 29
2.1 Numerical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.1.1 Multi-Beam HF Heating Model . . . . . . . . . . . . . . . . . . . . . 29
2.1.2 Temperature Modulation . . . . . . . . . . . . . . . . . . . . . . . . 33
2.1.3 Conductivity Modulation . . . . . . . . . . . . . . . . . . . . . . . . 35
2.2 Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.3 Extension to Other AM Waveforms . . . . . . . . . . . . . . . . . . . . . . 45
2.4 Extension to X- and O-Mode Polarization of the CW Beam . . . . . . . . . 49
3 ELF/VLF WAVE GENERATION USING SIMULTANEOUS CW AND
MODULATED HF HEATING OF THE IONOSPHERE . . . . . . . . . . . . . . . 52
3.1 Description of the Experiment . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.2 Experimental Observations . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.2.1 ELF/VLF Magnitude . . . . . . . . . . . . . . . . . . . . . . . . . . 56
3.2.2 ELF/VLF Harmonic Ratio . . . . . . . . . . . . . . . . . . . . . . . 59
3.2.3 ELF/VLF Power-Law Exponent . . . . . . . . . . . . . . . . . . . . 61
3.3 Model Predictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
6
3.3.1 ELF/VLF Magnitude . . . . . . . . . . . . . . . . . . . . . . . . . . 63
3.3.2 ELF/VLF Harmonic Ratio . . . . . . . . . . . . . . . . . . . . . . . 66
3.3.3 ELF/VLF Power-Law Exponent . . . . . . . . . . . . . . . . . . . . 68
3.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4 ELF/VLF WAVE GENERATION AS A FUNCTION OF POWER, FREQUENCY,
MODULATION WAVEFORM, AND RECEIVER LOCATION . . . . . . . . . . . 72
4.1 Description of the Experiment . . . . . . . . . . . . . . . . . . . . . . . . . 72
4.2 Description of the Data Set . . . . . . . . . . . . . . . . . . . . . . . . . . 74
4.3 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4.3.1 CW HF Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
4.3.2 CW HF Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
4.3.3 Beam 1(Modulated) HF Frequency . . . . . . . . . . . . . . . . . . 83
4.3.4 Modulation Waveform . . . . . . . . . . . . . . . . . . . . . . . . . 84
4.3.5 Receiver Location . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4.3.6 Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.3.7 Modulation Frequency . . . . . . . . . . . . . . . . . . . . . . . . . 91
4.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5 TIME-OF-ARRIVAL (TOA) MEASUREMENTS AS A MEANS
TO DETECT D-REGION STRUCTURE . . . . . . . . . . . . . . . . . . . . . . 94
5.1 Coupled Nature of N and T Profiles . . . . . . . . . . . . . . . . . . . . 95
e e
5.2 Linear T Profiles and Exponential N Profiles . . . . . . . . . . . . . . . . 96
e e
5.2.1 Matching Observations on 25 July 2011 . . . . . . . . . . . . . . . 100
5.3 Dual-Beam ELF/VLF TOA Observations . . . . . . . . . . . . . . . . . . . 102
5.3.1 Fitting a Piecewise-Exponential N Profile Using TOA . . . . . . . . 108
e
5.3.1.1 Lower Section (cid:12) . . . . . . . . . . . . . . . . . . . . . . . 108
5.3.1.2 Altitude of Intersection (h′ ) . . . . . . . . . . . . . . . . . 109
int
5.3.1.3 The Magnitude of N . . . . . . . . . . . . . . . . . . . . . 110
e
5.3.1.4 Upper Section (cid:12) . . . . . . . . . . . . . . . . . . . . . . . 111
5.4 Best Fit Piecewise-Exponential Profile . . . . . . . . . . . . . . . . . . . . 112
6 SUMMARY AND FUTURE WORK . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.1 Weighted Least Square Implementation . . . . . . . . . . . . . . . . . . . 115
6.2 Extension to Higher Harmonics . . . . . . . . . . . . . . . . . . . . . . . . 116
6.3 HF Frequencies Within a Collision Frequency . . . . . . . . . . . . . . . . 116
6.4 Evaluation of Ionospheric Current Drive (ICD) . . . . . . . . . . . . . . . . 116
6.5 HF Cross-Modulation Under Dual-Beam Heating Conditions . . . . . . . . 117
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
BIOGRAPHICAL SKETCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
7
LIST OF TABLES
Table page
1-1 Receiver Latitude, Longitude, and Distance (km) from HAARP. . . . . . . . . . 25
2-1 HF beam parameters for model input. . . . . . . . . . . . . . . . . . . . . . . . 31
4-1 1225 Hz SNR at each site for each day. . . . . . . . . . . . . . . . . . . . . . . 78
5-1 Experimental TOA observations. . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5-2 Piecewise-Exponential N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
e
8
LIST OF FIGURES
Figure page
1-1 Constituent parameters in the D-region. . . . . . . . . . . . . . . . . . . . . . . 17
1-2 Electron concentrations derived from various rocket sounding techniques. . . . 19
1-3 The HAARP HF heating facility. . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
1-4 A map of the ground based receiver locations. . . . . . . . . . . . . . . . . . . 26
1-5 Receiver system deployed to measure radial and azimuthal B-fields. (Photo
courtesy of Divya Agrawal.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2-1 D-region ambient electron density and temperature profiles. . . . . . . . . . . . 30
2-2 3-D beam patterns and 2-D slices of the HF power patterns transmitted by
HAARP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2-3 Amplitudes of three harmonics for Hall, Pedersen, and Parallel conductivities. . 36
2-4 3-D representation of HF-heated regions and radiation. . . . . . . . . . . . . . 38
2-5 Difference in conductivity modulation with electrojet E-field. . . . . . . . . . . . 39
2-6 Absolute magnetic field strength for electrojet field of 5 mV/m and 100 mV/m. . 41
2-7 Numerical predictions: 1215 Hz Hall current B-field amplitudes. . . . . . . . . . 42
2-8 Numerical predictions: 1215 Hz Pedersen current B-field amplitudes. . . . . . . 43
2-9 Numerical predictions: 2430 Hz Hall current B-field amplitudes. . . . . . . . . 45
2-10 Numerical predictions: 2430 Hz Pedersen current B-field amplitudes. . . . . . 46
2-11 Steady state T as a function of time for various altitudes. . . . . . . . . . . . . 47
e
2-12 Max and min T as a function of altitude for five different modulation waveforms. 48
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2-13 Maximum and minimum T achieved as a function of CW ERP. . . . . . . . . . 48
e
3-1 A cartoon diagram of the dual-beam HF heating experiment. . . . . . . . . . . 53
3-2 The transmission schedule for the modulated HF beam. . . . . . . . . . . . . . 54
3-3 Magnitude of ELF/VLF signals observed at HAARP. . . . . . . . . . . . . . . . 55
3-4 ELF/VLF measurements: Statistical distributions. . . . . . . . . . . . . . . . . . 57
3-5 Magnitude of the 1st harmonic observed during peak power transmissions. . . 58
3-6 Ratio of the second to the first harmonic magnitude. . . . . . . . . . . . . . . . 61
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3-7 The power-law exponent at 1215 Hz and 2430 Hz for each power-step series. . 62
3-8 Numerical predictions: Total B-field magnitude at the receiver. . . . . . . . . . . 64
3-9 Numerical predictions: change in B-field magnitude (CW-OFF / CW-ON). . . . 65
3-10 ELF/VLF harmonic ratio. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3-11 Numerical predictions. (A) n at 1215; (B) n at 2430 Hz; (C) The change in n
from CW-OFF to CW-ON conditions. . . . . . . . . . . . . . . . . . . . . . . . . 69
4-1 Cartoon diagram of the dual-beam HF heating experiment. . . . . . . . . . . . 73
4-2 1225 Hz signal magnitude observed at Paradise (PD). . . . . . . . . . . . . . . 75
4-3 90-second spectrograms of ELF/VLF observations at Paradise. . . . . . . . . . 76
4-4 1225 Hz signal magnitudes observed on 20 July 2011 at PD. . . . . . . . . . . 77
4-5 Observations and model predictions for 1225 Hz signal magnitude. . . . . . . . 79
4-6 Normalized ELF magnitude as a function of CW ERP. . . . . . . . . . . . . . . 82
4-7 CW-OFF: ELF/VLF magnitude as a function of modulation waveform. . . . . . 85
4-8 ELF/VLF magnitude as a function of CW ERP for the five AM waveforms. . . . 86
4-9 Normalized ELF/VLF magnitude as a function of ELF/VLF receiver location. . . 88
4-10 Normalized ELF/VLF magnitude versus CW HF beam polarization. . . . . . . . 90
4-11 Normalized ELF/VLF magnitude for different modulation frequencies. . . . . . 91
5-1 ELF magnitude dependence on N and T profiles. . . . . . . . . . . . . . . . . 96
e e
5-2 Exponential N profiles with varying (cid:12) and h′. . . . . . . . . . . . . . . . . . . . 97
e
5-3 Linear T profiles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
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5-4 ELF magnitude as a function of (cid:12). . . . . . . . . . . . . . . . . . . . . . . . . . 99
5-5 ELF magnitude as a function of h′. . . . . . . . . . . . . . . . . . . . . . . . . . 99
5-6 Exponential Ne with (cid:12) 0.05, 0.1 km(cid:0)1 and h′ 90 km. . . . . . . . . . . . . . . . 101
5-7 Normalized ELF magnitude for (cid:12) of 0.05 and 0.10 km(cid:0)1 and h′ 90 km. . . . . . 102
5-8 Dominant source region for Hall conductivity with CW-OFF and CW-peak power.103
5-9 Absolute TOA and LOS amplitude observations with CW ERP. . . . . . . . . . 104
5-10 Relative TOA and normalized LOS amplitude observations with CW ERP. . . . 105
10