MSc Thesis

My Masters These entitled “SuperDARN Measurements of Double-Peaked Velocity Spectra” analyzed the radar backscatter signatures of the SuperDARN HF radar network. It was written under the supervision of Dr. G. Sofko at ISAS, University of Saskatchewan, Saskatoon, Canada.

SuperDARN Measurements of Double-Peaked Velocity Spectra

Abstract

The SuperDARN HF radars in Saskatoon, Sask. and Kapuskasing, Ont. have been used to measure Doppler velocity spectra of backscatter from the F-layer. A special multipulse sequence was developed to increase the number of measured autocovariance points. These spectra were used to benchmark spectral estimators based on the Fourier Transform and parametric spectral estimators. A parametric spectral estimator using the Burg algorithm improved the resolution of the spectra. A distinct double-peaked spectral signature was found in spatially localized regions. A comparison with particle data as measured by a DMSP satellite suggests a strong spatial correlation of soft-electron precipitation with great variability with the occurrence of the spectral features. Several generating mechanisms for double-peak spectra are suggested, including the Kelvin-Helmholtz instability and precipitation-induced electric fields in arc and ray structures.

Acknowledgements

I would like to thank Dr. G. Sofko for supporting me financially and academically throughout my graduate career at the University of Saskatchewan and during the making of this thesis. He has made it possible for me to pursue an academic career in Canada after my undergraduate years were completed and he has given me much freedom during my graduate work.

I would also like to thank all the members of the SuperDARN team here in Saskatoon for their generous supply of help, advice and encouragement that is so much needed for a graduate student. I hope to give something back to them with this thesis.

Finally, I would like to thank my wife Jennifer for putting up with my continued urge to explain all the details of my research to her — it has helped me focus and hopefully do a better job.

—

Online Masters These was generated from the original TeX document.

Index

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• Roadmap for this Thesis
• Physics of the Ionosphere
  • Basic Properties of the Earth’s Magnetosphere
    • The Solar Wind
    • The Geomagnetic Cavity
    • Circulation Patterns, Currents and Electric Fields
  • Magneto-ionic Theory and the Appleton-Hartree Equation
  • Refraction of an HF Radio Wave in the Ionosphere
  • Instabilities
    • Farley-Buneman Instability
    • Gradient Drift Instability
    • Kelvin-Helmholtz Instability
    • Instabilities Generated by Thermal Sources
• The SuperDARN HF radar
  • Coherent Scatter Radar and the Scatter Theorem
  • Introduction to SuperDARN
  • Operation of the Radar
    • Normal Operation
    • ACF Determination
      • Double-Pulse
  • Pulse Pattern Optimization
    • Double pulses with variable lag
    • Multipulse
  • Analysis of the Data
    • Normal ACF analysis using a Phase Fit
    • Power Spectrum Analysis using Spectral Estimators
• The DMSP F12 Satellite
  • The DMSP Satellite and the SSJ/4 Particle Analyzer
  • Analysis of the Particle Data
    • The AAGCM Coordinate System
    • Conductivity Estimation
    • Ionization Rate Estimation
• Experimental Results
  • Observation Periods
  • High-Resolution Autocorrelation Functions
  • Doppler-velocity Spectra with Two Close Peaks
  • Morphology during a Complete Scan
    • SuperDARN Maps of Double-peaked Doppler Velocity Spectra
    • 1 Jan/95, 16:21 – 16:23 UT
    • 6 Jan/95, 17:03 – 17:05 UT
    • 16 Jan/95, 16:45 – 16:47 UT
    • 26 Jan/95, 16:27 – 16:29 UT
    • 28 Jan/95, 2:13 – 2:15 UT
    • 18 Feb/95, 1:25 – 1:27 UT
    • 20 Feb/95, 16:32 – 16:34 UT
    • 21 Feb/95, 2:30 – 2:32 UT
    • 25 Feb/95, 1:42 – 1:44 UT
• Discussion
• Conclusion and Summary
• References
• Computer Programs
  • Multipulse Sequencer
  • SuperDARN Autocovariance Function Processing Tools
  • DMSP SSJ/4 Data Analysis and Processing
• Acronyms
• About this document …

3D SuperDARN Merge Maps

SuperDARN merg-map animation video clips in MPG format.

The following animations were created by me while learning about the data analysis tools for SuperDARN. The data sets are “merge maps” based on measurements of the Saskatoon and Kapuskasing radars – a standard SD data product. The vector locations are positioned in 3D space based on an assumed F-layer height, a magnetic model and mapped to a geographic location at a specific height above the earth. The resulting map was parsed by a C program into a PovRay script, raytraced over night and the final images assembled into an MPG video using mpeg_encode.

• Clip 1: 4030618_1.mpg (.mpg, 737MB)
• Clip 2: 4030618_2.mpg (.mpg, 608MB)
• Clip 3: 4030618_3.mpg (.mpg, 505MB)

 

Mapping the outer LLBL with SuperDARN double-peaked spectra

GRL Paper, 1997

Andreas Schiffler and George Sofko
Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, SK

Patrick T. Newell and Ray Greenwald
Johns Hopkins University Applied Physics Laboratory, Laurel, MD

Abstract

A SuperDARN HF radar pair (Saskatoon- Kapuskasing) has been used to measure Doppler spectra of backscatter from the dayside F-layer. Normally the spectra are single-peaked, but a small fraction exhibit a doublepeaked (D-P) signature. On the 2D convection maps, these D-P spectra occur in range cells located poleward of the convection reversal. A comparison with DMSP SSJ/4 particle data measurements and their mapping to magnetospheric boundaries shows that the D-P spectra are concentrated just equatorward of the magnetopause, in regions of spatially/temporally structured soft electron precipitation (about 300 eV) where the highly variable flux can reach 2- 5 ergs=cm2=s. The D-P spectra are most easily explained in terms of scattering from small-scale vortices of size less than the radar resolution of 45 km. The D-P spectral measurements are illustrated by SuperDARN and DMSP data for a dayside event on Feb. 20, 1995, when northward IMF conditions prevailed. We conclude that HF radar D-P observations can be used to map in real time the dayside 2D ionospheric footprint of the outer LLBL.

• Paper (.pdf, 986K)
• Diagram 1 (.eps)
• Diagram 2 (.eps)
• Diagram 3 (.eps)

BibteX

@article {GRL:GRL10812,
author = {Schiffler, Andreas and Sofko, George and Newell, Patrick T. and Greenwald, Ray},
title = {Mapping the outer LLBL with SuperDARN double-peaked spectra},
journal = {Geophysical Research Letters},
volume = {24},
number = {24},
issn = {1944-8007},
url = {http://dx.doi.org/10.1029/97GL53304},
doi = {10.1029/97GL53304},
pages = {3149--3152},
keywords = {Ionosphere: Particle precipitation, Ionosphere: Plasma convection},
year = {1997},
}

 

Masters Thesis Software

Data analysis software use for Masters Theses as source code: SuperDARN/DMSP analysis software used for MSc theses (1001k).

Download

sd_analysis.tar.gz