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Space @ VT

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SuperDARN is the sole instrument that is capable of providing direct measurements of plasma convection and electric fields in the ionosphere on global scales with high temporal resolution.

SuperDARN

For the past 15 years, engineers and scientists have gained a greater understanding of global warming, the effects of geomagnetic storms, the impact of the solar wind interacting on the magnetized region around the earth, and other dynamic processes that occur in the Earth’s near-space environment.

Among their tools, they use a high-latitude network of radars to obtain increasingly sophisticated views of electric fields, plasma structures, atmospheric waves, and other effects in the ionosphere and atmosphere.

Graphic showing coverage of SuperDARN over the north pole

The radars have an elaborate technical name — the Super Dual Auroral Radar Network — providing an acronym with a humorous touch, SuperDARN. The network is an international collaboration with support provided by the funding agencies of more than a dozen countries. The radars combine to give extensive views of the upper atmosphere in both the Arctic and Antarctic regions.

The view is about to get much bigger.

ECE’s J. Michael Ruohoniemi is the lead principal investigator on a new $6 million grant to build additional radar units. Nearly $2 million of the award will go to the Center for Space Science and Engineering Research (Space@VT).

Other participants in the grant from the National Science Foundation (NSF) are Dartmouth College, University of Alaska at Fairbanks, and the Johns Hopkins University Applied Physics Laboratory (JHU/APL). The ECE group is directing the first construction that will take place at a site in Kansas later this year. Other potential sites are currently being reviewed in Oregon, the Aleutian Islands, and the Azores.

Construction of the new radars will occur in pairs at a rate one pair per year at each of four sites, for a total of eight radars over four years. The new radars will join three existing mid-latitude radars to make up a continuous chain of coverage that extends from Europe to eastern Asia.

As Ruohoniemi explained the science, “The Earth’s magnetosphere is immersed in the tenuous, fully-ionized outer atmosphere of the sun, which is responsible for the solar wind and its structured and dynamic magnetic field. In the aftermath of severe solar disturbances, such as solar flares, energized solar wind plasma impinges on the Earth’s magnetic and plasma environment and initiates a broad range of interactions. These reactions lead to the onset of disturbances in the magnetosphere.

“During these events, the magnetosphere-ionosphere system passes through a range of states that can be described as quiescent, mildly disturbed, and storm-like. As each transition takes place, the effects of disturbance reach to ever increasing fractions of the Earth’s plasma environment. The consequences of these solar-induced disturbances are often described as space weather and they can threaten harm to humans in space, perturb spacecraft orbits, damage spacecraft electronics, and disrupt radio, radar, and GPS operations.”

SuperDARN array

SuperDARN array at Blackstone, Virginia

Virginia Tech has operated a midlatitude radar at the University’s Blackstone Agricultural Research and Extension Center since February 2008. Ruohoniemi and Joseph Baker are responsible for its daily operation and share in the responsibility for the operation of a radar at the NASA Wallops Flight Facility located at Wallops Island. Ray Greenwald, considered the “godfather” of the SuperDARN group, is now retired from JHU/APL, but continues to work as a research professor with Space@VT. The ECE group also manages two older SuperDARN radars located at auroral sites in Labrador and northern Ontario.

With the new midlatitude infrastructure, researchers will be able to observe substorm processes at lower latitudes than is currently possible. They will also be able to merge overlapping measurements from pairs of radars to map the structure within substorm flows at high spatial and temporal resolutions.

—by Lynn Nystrom