Instrument Info
Each riometer site is equipped with a 30 MHz zenith oriented, 4-element antenna and a single 150 kHz broadband receiver. These instuments were supplied by La Jolla Sciences of Solana Beach, California. |
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How it Works |
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A riometer is a radio receiver. Tuned to frequencies of 20-60MHz a riometer monitors the flux of cosmic radio waves travelling through the ionosphere. As radio waves traverse the ionosphere they induce oscillations in the free electron population. If the electrons then come in collisional contact with neutral atoms the waves begin to lose energy (they are attenuated). From the ground, this is a perceived reduction in signal strength. |
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The key to using riometers is to remove the background/cosmic signal (also called a quiet day curve) to find absorptions induced by higher than normal ionospheric electron densities. |
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These increased electron densities are, for the most part, produced by the precipitation of high energy particles into the upper atmosphere. These tend to be >30keV electrons. |
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