Researchers and Affiliations: J. Kinrade, C. N. Mitchell, N. Smith, Department of Electronic and Electrical Engineering, University of Bath, Bath, UK; P. Yin, University of Bath and College of Electronic Information Engineering, Civil Aviation University of China, Tianjin, China; M. J. Jarvis, D. J. Maxfield, M. C. Rose, Physical Sciences Division, British Antarctic Survey, Cambridge, UK; G. S. Bust, Atmospheric and Space Technology Research Associates, USA – now at Johns Hopkins University Applied Physics Laboratory, USA; and A. T. Weatherwax, Department of Physics, Siena College, Loudonville, New York, USA.
Written by Linda Rowan
25 February 2012
A coronal mass ejection (CME) from the Sun that was directed toward the Earth created a significant ionospheric and geomagnetic disturbance at the South Pole. Observations from satellites, the Antarctic GPS network and seven GPS scintillation receivers installed in 2010 mapped out the disturbance. Energetic electrons and protons rained down on Antarctica in a complex dance with the Earth’s magnetic field and ionosphere. Understanding these interactions is important because solar storms can affect satellites and ground-based systems, causing problems with navigation, communications, power and many other technologies used on a daily basis.
CMEs are giant bursts of highly energetic plasma that are driven off the surface of the Sun. When a solar storm collides with the Earth it compresses the dayside (facing the Sun) and elongates the nightside of the Earth’s magnetosphere. The hot, energetic ions in the solar storm are driven along and down Earth’s magnetic field lines toward both poles creating magnificent auroras. The auroras form when the solar particles ionize or energize nitrogen or oxygen in the uppermost atmosphere creating outstanding emissions of green, red or blue light.
A suite of Sun-observing satellites can follow a CME and the approaching solar storm. Networks of ground-based GPS receivers detect changes in the magnetosphere and ionosphere because the networks are constantly sampling these regions as part of the pathway between the GPS satellites and receivers.
On 5 April 2010, a CME deposited a massive burst of hot and energetic plasma at the Earth. The high-energy solar plasma (ultraviolet to gamma ray photons) began interacting with Earth’s magnetosphere within 40 minutes of the ejection being detected by satellites. Then the number of protons and electrons started growing, concentrating and re-concentrating throughout the magnetosphere and raining down on Earth through the converging magnetic field lines at both poles. Fifty permanent GPS stations that are part of the Antarctic system maintained by UNAVCO sample the ionosphere while seven GPS scintillation receivers, deployed by the University of Bath (UK) in January of 2010 within the southern auroral zones and polar cap, decipher scintillation produced by turbulence and storms of ionized particles (see Figure 1).
Three distinct phases of scintillation were observed over 2 days (5 and 6 April 2010). Bursts of 30-second scintillations were observed when the plasma intersected with the dayside cusp of the magnetosphere. A ten-hour period of scintillation was then associated with the plasma breaking off from the dayside cusp and raining down toward the polar cap (shown in Figure 2 by drift of plasma from western to eastern then southern Antarctica). Finally on the second day (6 April 2010), scintillation was associated with plasma reconnecting on the nightside of the magnetosphere even though the total electron content in the ionosphere was low.
The combination of satellite, GPS and GPS scintillation observations provides a rich mapping of the interaction of a solar storm with Earth’s magnetosphere and ionosphere. The three scintillation events combined with mapping of the structure of the ionosphere indicates that the scintillations are likely related to particle precipitation at the poles. These results improve our understanding of solar and terrestrial interactions. In addition the observations will help society deal with disturbances that can disrupt satellite and ground-based operations, such as communications, navigation and power.
Kinrade, J., C. N. Mitchell, P. Yin, N. Smith, M. J. Jarvis, D. J. Maxfield, M. C. Rose, G. S. Bust, and A. T. Weatherwax (2012), Ionospheric scintillation over Antarctica during the storm of 5–6 April 2010, J. Geophys. Res., 117, A05304, doi:10.1029/2011JA017073.
Kinrade, J., C. N. Mitchell, N. D. Smith, Y. Ebihara, A. T. Weatherwax, and G. S. Bust (2013), GPS phase scintillation associated with optical auroral emissions: first statistical results from the geographic South Pole, J. Geophys. Res., submitted January 2013.
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Ionospheric scintillation, coronal mass ejection, magnetosphere, ionosphere
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