1. near-Space Environment
The Virginia Tech SuperDARN Group: Using Radars to Study Weather in Earth’s
near-Space Environment
Dr. J. Michael Ruohoniemi
Center For Space Science and Engineering Research
Bradley Department of Electrical and Computer Engineering
Virginia Tech
September 14, 2012
Mike Ruohoniemi
Engineering Research Seminar 2012
VT SuperDARN

2. Artist’s rendering of a solar flare event
Space weather arises from collision of the Solar Wind
with Earth’s Magnetosphere
Artist’s rendering of a solar flare event

3. Space weather funnels energy into Earth’s Upper Atmosphere
Photograph of a display of aurora borealis (northern lights)

4. Virginia Tech operates Space Weather research radars as part of the Super Dual Auroral Radar Network (SuperDARN)
Kapuskasing, Ontario, Canada
Goose Bay, Newfoundland and Labrador, Canada
Fort Hays, Kansas, USA
Blackstone, Virginia, USA

5. Mapping the Motion of Plasma in the Ionosphere
Doppler velocity map obtained form a single 2-min radar scan
Velocity magnitude
Blue - towards
Red - away

6. Coverage by the SuperDARN radars
The radars operate continuously, all data are shared

7. SuperDARN PI Institutions
Johns Hopkins University Applied Physics Laboratory, USA (1983)
British Antarctic Survey, UK (1988)
University of Saskatchewan, Canada (1993)
Centre National de la Recherche Scientifique, France (1994)
National Institute for Polar Research, Japan (1995)
University of Leicester, UK (1995)
University of KwaZulu-Natal, South Africa (1997)
La Trobe University, Australia (1999)
University of Alaska Fairbanks, USA (2000)
National Institute of Information and Communications Technology , Japan (2001)
Nagoya University, Japan (2008)
Virginia Tech, USA (2008)
Polar Research Institute of China (2010)
Dartmouth College, USA (2010)
Institute of Solar Terrestrial Physics, Russia (2012)
Mike Ruohoniemi

8. Large-Scale Mapping of Ionospheric Plasma Convection
Virginia Tech SuperDARN – An NSF Geospace Facility
Large-Scale Mapping of Ionospheric Plasma Convection
September 30, 2002: 09:50 – 09:52 UT
Northern Hemisphere
Southern Hemisphere
Mike Ruohoniemi
Engineering Research Seminar 2012

9. Propagation and Reflection of HF Signal
Primer on HF Radar
Propagation and Reflection of HF Signal B
Ionospheric plasma irregularities
F-Region
~ 300 km altitude
HF radar
Ground Scatter
HF rays are refracted in the ionosphere as they encounter gradients in electron density.
Transmitted signals can be reflected back to the radar by:
1) Ionospheric plasma irregularities
OR 2) Earth’s surface
Information about the reflectors is carried in the returned signal, e.g., Doppler velocity

10. Primer on HF Radar
High Frequency (HF) radars operate at ~10 MHz (wavelengths of ~30 m)
An early success of HF radar as a remote sensing device was the discovery of the ionosphere (from reflections)
The ionosphere is the layer of the atmosphere that contains weakly ionized plasma and extends upwards from about 90 km
HF rays are bent, or refracted, by the ionosphere and can propagate to great distances leading to:
Short wave radio propagation
Over-The-Horizon (OTH) radar
An HF radar can detect scatter from blobs, or irregularities, in the ionosphere and from structure on Earth’s surface

11. Map of Line-of-Sight Velocities for 08:40 UT, March 9th, 2011
NSF MSI SuperDARN
MSI SuperDARN:
First Extended, Instantaneous Image of a SAPS Flow Channel
Christmas Valley, OR
Hays, KS
First extended, instantaneous image of a SAPS event recorded on March 9th, 2011 at 08:40 UT. Line-of-sight velocities are shown.
Map of Line-of-Sight Velocities for 08:40 UT, March 9th, 2011

12. Total Electron Content of the Ionosphere with GPS
Engineering Research Seminar 2012
Total Electron Content of the Ionosphere with GPS
Comparison with SuperDARN observations of irregularity backscatter
Mid-latitude SuperDARN radars observed high-speed flows associated with a subauroral polarization stream (SAPS) in the TEC trough region.

13. Waves in the Atmosphere
Atmospheric Gravity Waves
Waves in the Atmosphere
They are called gravity waves because gravity is the restoring force. Waves on the ocean surface are also gravity waves.
SuperDARN is excellent for Iding Traveling Ionospheric Disturbances associated with medium Scale atmospheric gravity waves [Samson et al., 1990].
Neutral-atmosphere pressure variations due to gravity waves couple to the bottomside ionosphere.
Time lapse of gravity wave action from the Tama, Iowa KCCI-TV webcam on 6 May 2007. [
Mike Ruohoniemi
Engineering Research Seminar 2012

14. HF Radar Observations of Atmospheric Gravity Waves
Goose Bay Radar (GBR)
19 November 2010
They are called gravity waves because gravity is the restoring force. Waves on the ocean surface are also gravity waves.
SuperDARN is excellent for Iding Traveling Ionospheric Disturbances associated with medium Scale atmospheric gravity waves [Samson et al., 1990].
Neutral-atmosphere pressure variations due to gravity waves couple to the bottomside ionosphere.
Mike Ruohoniemi
Engineering Research Seminar 2012

15. Mapping the Roughness of Earth’s Surface
Comparison of sea ice cover and HF radar observations
Furthest extent of sea ice cover during month of October 2000 (National Snow and Ice Data Center, Boulder, CO).
Ground scatter occurrence rate observed by the radar at Goose Bay during daytime over the month of October 2000.

16. Summary of Virginia Tech SuperDARN Research
The SuperDARN group at Virginia Tech operates HF radars as part of an international research collaboration (10 countries)
SuperDARN: Super Dual Auroral Radar Network
Part of the Research Center at Virginia Tech (rockets, satellites, GPS, etc.)
The radars observe:
The motion of ionospheric plasma (‘plasma winds’)
Passage of large-scale waves in the atmosphere
Roughness at the Earth’s surface including ocean waves and ice cover
Winds in the atmosphere at 90 km altitude (from meteor trails)
Unusual clouds in the upper atmosphere (Polar Mesopheric Clouds)

17. VT SuperDARN IT and Networking: web page

18. VT SuperDARN RF Engineering
Hardware projects include design and construction of radar systems

19. The Virginia Tech SuperDARN Group
The overall aim is to understand Space Weather and its impact on vulnerable technological systems
Student opportunities include:
Research on the causes and effects of weather in Earth’s near-space environment
RF engineering
Engagement with a large international science collaboration
Travel to radar sites, professional meetings
IT and Networking, development of cyber infrastructure
Engagement with the wide range of space research conducted by partner groups within