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Overview of Changes and Developments in the SuperDARN Upper Atmosphere Facility

Overview of Changes and Developments in the SuperDARN Upper Atmosphere Facility. Raymond A. Greenwald, J. Michael Ruohoniemi, Joseph B. H. Baker Bradley Department of Electrical and Computer Engineering Virginia Tech Elsayed Talaat and Robin Barnes

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Overview of Changes and Developments in the SuperDARN Upper Atmosphere Facility

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  1. Overview of Changes and Developments in the SuperDARN Upper Atmosphere Facility Raymond A. Greenwald, J. Michael Ruohoniemi, Joseph B. H. Baker Bradley Department of Electrical and Computer Engineering Virginia Tech Elsayed Talaat and Robin Barnes Johns Hopkins University Applied Physics Laboratory Presented at the 2008 NSF Upper Atmosphere Facilities Workshop Space @ Virginia Tech Space @ Virginia Tech 1

  2. Organizational Changes • Virginia Tech is now the Principal Investigator Institution of the U.S. SuperDARN Upper Atmosphere Facility. • Transition brought about by: • Retirement of Ray Greenwald from JHU/APL. • Academic appointments of Mike Ruohoniemi and Joseph Baker at Virginia Tech. • JHU/APL remains a collaborating partner within the SuperDARN UAF. • Effort carried out by Elsayed Talaat and Robin Barnes. Space @ Virginia Tech

  3. Motivations for Change • Virginia Tech offers significantly greater opportunities for student training and development. • Virginia Tech has provided considerable institutional support for the development of the SuperDARN research effort. Space @ Virginia Tech

  4. New Organizational Staffing • Virginia Tech • J. Michael Ruohoniemi: Associate Professor in Department of Electrical and Computer Engineering (ECE) • Joseph B. H. Baker: Assistant Professor in ECE • Raymond A. Greenwald: Part-time Research Professor in ECE • JHU/APL • Elsayed Talaat JHU/APL Science Lead • Robin Barnes Software Development Space @ Virginia Tech

  5. Organizational Responsibilities • Virginia Tech • Radar operations and maintenance • Scientific research • Community support • Education and outreach • JHU/APL • Scientific research • Software development • Community support • Outreach • Data distribution Space @ Virginia Tech

  6. Development of SuperDARNNorthern Hemisphere Situation Today Viewgraph from 2005 UAF Meeting Space @ Virginia Tech

  7. SuperDARN – Northern HemisphereFuture Development The right-hand map includes all of the radars shown at the left plus eight radars extending from the Azores to the Aleutians that constitute an NSF MSI proposal and a single radar in violet located in the U.K. Also, shown are additional radars identified by faint dashed lines that have been proposed by other countries to various funding agencies. Space @ Virginia Tech

  8. Technology InnovationGreenwald Twin-Terminated Folded Dipole Antenna • The TTFD antenna has proven to be a major improvement in SuperDARN antenna usage. • Reduced cost • Improved azimuthal coverage • Improved front-to-back ratio • More rugged due to fewer electrical connections and lower wind loading • Used at Wallops Island, Blackstone, Rankin Inlet, Inuvik, and Antarctica Space @ Virginia Tech

  9. TTFT Antenna Performance Space @ Virginia Tech

  10. Technology InnovationForward and Reverse Optimal Golomb Sequences • In 1972, Farley was the first to apply the concept of Golomb rulers to radar measurements in the Earth’s ionosphere. • Within the radar community, this technique is commonly referred to as multipulse sequences. • Multipulse sequences provide a means of resolving the range-time ambiguities that are common to radar Doppler measurements when there are spread targets with significant Doppler velocities. • However, multipulse techniques are notorious for adding noise due to other transmitter pulses and their returns to the analysis process. • 6-pulse optimal ruler • Possible distances = 5+4+3+2+1 = 15 • Length = 17 Missing: 10,15 7 4 2 3 1 Space @ Virginia Tech

  11. Technology InnovationForward and Reverse Optimal Golomb Sequences • The pattern above is a 13-pulse sequence consisting of a single pulse followed by forward and reverse 6-pulse optimal Golomb sequences. • This pattern is resistant to bad lags due to transmitter pulses and strong cross range noise. • In most instances there is at least one good option for each lag. Space @ Virginia Tech

  12. Technology InnovationForward and Reverse Optimal Golomb Sequences Farley, 1972 Value=0: Data Sample Value=1: Tx Pulse Value=2: Data Sample>10dB 3 2 Sample Type 1 0 0 50 100 150 200 250 300 350 Sample No. Sample types occurring during a 6-pulse Golomb sequence preceded by a single pulse. Range Gates 10-14 have >10 db signal Space @ Virginia Tech

  13. Technology InnovationForward and Reverse Optimal Golomb Sequences Bad Lags due to Transmitter Pulses and Cross-Range Noise on First 100 Ranges Gates Using Farley Sequence. 7-Pulse Sequence: 15,1,7,4,2,3 Cross-range noise: Range Gates 10-14 Space @ Virginia Tech

  14. Technology InnovationForward and Reverse Optimal Golomb Sequences Bi-Directional - 13-Pulse Sequence Value=0: Data Sample Value=1: Tx Pulse 3 What happens if we have a choice between two potential solutions for each tau? 2 Farley Sequence Farley Sequence Reversed Sample Type 1 0 0 100 200 300 400 500 600 Sample No. Space @ Virginia Tech

  15. Technology InnovationForward and Reverse Optimal Golomb Sequences 15 10 Bad Lags 5 0 0 20 40 60 80 100 Range Gate Bad lags due to transmitter pulses for 13-pulse forward and reverse sequence. Space @ Virginia Tech

  16. Technology InnovationForward and Reverse Optimal Golomb Sequences (>10 dB Signals at range gates 10-14) (>10 dB Signals at range gates 15-19) Bad lags due to Tx pulse and cross-range noise is highly variable and depends on interplay between two independent processes. Space @ Virginia Tech

  17. Improved Phase Vs. Lag Measurements Allow Doppler Velocities to be Determined from Individual Pulse Sequences Space @ Virginia Tech

  18. Doppler Velocity Vs. Time200 ms Temporal Resolution Space @ Virginia Tech

  19. 14-sec Doppler Velocity Pulsation Observed With Wallops Island Radar (Greenwald et al., 2008) Note Similar period on Ottawa magnetometer Space @ Virginia Tech

  20. Science: Extended Observations of Sub-Auroral Plasma Streams (Oksavik et al., 2006) Space @ Virginia Tech

  21. Science: Identification of Temperature Gradient Instability Onset (Greenwald et al., 2006) 22 23 00 01 02 03 04 UT Sequence of Events 22-00 UT: Poleward motion of ocean scatter footprint following sunset. 00-0120 UT: Irregularities form in post-sunset ionosphere. Possibly associated with F-region gradient-drift instability as reported previously. 0120 UT onwards: Temperature gradient reverses and steepens. Backscatter intensifies. Onset of TGI. Space @ Virginia Tech

  22. THEMIS-SuperDARN Substorm Studies • During THEMIS tail conjunctions SuperDARN radars run a special THEMIS mode that increase temporal sensitivity to substorm dynamics: • Dwell time reduced from 7 to 4 seconds. • SD radars returns to a designated camping-beam between each successive scan beam. THEMIS Mode camping beams (Blue) Space @ Virginia Tech

  23. THEMIS-SuperDARN Substorm StudiesFebruary 22, 2008 Beam-8: normal scan data (2-minutes) Beam-7: camping beam data (8-second) 0430 UT 0440 UT 0450 UT • Substorm expansion phase onset at approximately 0437 UT: • THEMIS spacecraft measure two bursts of Earthward convection in the tail. • Ground-based magnetometers measure the onset of Pi2 oscillations. • Blackstone Radar Measurements: • Pi2 oscillations measured on camping beam at approximately location of plasmapause (Alfven Waves?). Space @ Virginia Tech

  24. Science: Upper Atmosphere Variability at Mid-Latitudes Space @ Virginia Tech

  25. Education and TrainingAdvanced Degree Students @ Virginia Tech Student Advanced Degree Nathaniel Frissell PhD Yin Yan PhD Kevin Sterne MS Frederick Wilder (Bob Clauer) PhD Lyndell Hockersmith (Bob Clauer) MS Space @ Virginia Tech

  26. SuperDARN: Issues and Concerns • The reconstitution of the JHU/APL SuperDARN activity at Virginia Tech and JHU/APL will still require some time to bring to completion. At Virginia Tech, • We have a good group of involved students. • We hope to add an engineer with SuperDARN experience. • Goose Bay and Kapuskasing have upgrade/ maintenance needs: • Kapuskasing: digital receiver • Kapuskasing and Goose Bay: new low-loss cables • Kapuskasing and Goose Bay: potential antenna deterioration • Serious issues in obtaining maintenance support at Wallops Space @ Virginia Tech

  27. SuperDARN: Issues and Concerns • Air Force infrastructure support for Goose Bay disappearing • Ionosonde no longer in operation • No Air Force funds for heat, electricity, or snow plowing • Death of Dr. Jean-Paul Villain raises concerns about future support for Stokkseryi radar • We are working with University of Leicester to identify magnitude of problem and possible solutions. • Full SuperDARN network can produce 4+TB of data samples per year. How do we gather and disseminate data? Space @ Virginia Tech

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