Overview of Changes and Developments in the SuperDARN Upper Atmosphere Facility

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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

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Space _at_ Virginia Tech
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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.

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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.

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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

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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

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Development of SuperDARNNorthern Hemisphere
Situation Today
Viewgraph from 2005 UAF Meeting
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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.
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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

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TTFT Antenna Performance
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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 Earths 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 54321 15
• Length 17 Missing 10,15

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4
2
3
1
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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.

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Technology InnovationForward and Reverse Optimal
Golomb Sequences
Sample types occurring during a 6-pulse Golomb
sequence preceded by a single pulse.
Range Gates 10-14 have gt10 db signal
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Technology InnovationForward and Reverse Optimal
Golomb Sequences
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Technology InnovationForward and Reverse Optimal
Golomb Sequences
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Technology InnovationForward and Reverse Optimal
Golomb Sequences
Bad lags due to transmitter pulses for 13-pulse
forward and reverse sequence.
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Technology InnovationForward and Reverse Optimal
Golomb Sequences
Bad lags due to Tx pulse and cross-range noise is
highly variable and depends on interplay between
two independent processes.
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Improved Phase Vs. Lag Measurements Allow Doppler
Velocities to be Determined from Individual Pulse
Sequences
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Doppler Velocity Vs. Time200 ms Temporal
Resolution
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14-sec Doppler Velocity Pulsation Observed With
Wallops Island Radar (Greenwald et al., 2008)
Note Similar period on Ottawa magnetometer
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Science Extended Observations of Sub-Auroral
Plasma Streams (Oksavik et al., 2006)
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Science Identification of Temperature Gradient
Instability Onset (Greenwald et al., 2006)
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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)
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THEMIS-SuperDARN Substorm StudiesFebruary 22,
2008
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?).
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Science Upper Atmosphere Variability at
Mid-Latitudes
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Education and TrainingAdvanced Degree Students _at_
Virginia Tech

• Student Advanced Degree
• Nathaniel Frissell PhD
• Yin Yan PhD
• Kevin Sterne MS
• Frederick Wilder (Bob Clauer) PhD
• Lyndell Hockersmith (Bob Clauer) MS

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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

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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 4TB of data
  samples per year. How do we gather and
  disseminate data?