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The Super Dual Auroral Radar Network (SuperDARN) is an international scientific radar network consisting of 35 high frequency (HF) radars located in both the Northern and Southern Hemispheres. SuperDARN radars are primarily used to map high-latitude plasma convection in the F region of the ionosphere, but the radars are also used to study a wider range of geospace phenomena including field aligned currents, magnetic reconnection, geomagnetic storms and substorms, magnetospheric MHD waves, mesospheric winds via meteor ionization trails, and interhemispheric plasma convection asymmetries.〔 The SuperDARN collaboration is composed of radars operated by JHU/APL, Virginia Tech, Dartmouth College, the Geophysical Institute at the University of Alaska Fairbanks, the Institute of Space and Atmospheric Studies at the University of Saskatchewan, the University of Leicester, La Trobe University, and the Solar-Terrestrial Environment Laboratory at Nagoya University. == History == In the 1970s and 1980s, the Scandinavian Twin Auroral Radar Experiment (STARE) very high frequency (VHF) coherent scatter radars were used to study field aligned E region ionospheric irregularities. Using two radars with overlapping fields of view, it was possible to determine the 2D velocity vector of E region ionospheric plasma flow.〔 However, irregularities were only observed when the radar wavevector was perpendicular to the magnetic field in the scattering region. This meant that there was a problem with operating at VHF since VHF frequencies don't allow for very much refraction of the transmitted radar wave vector; thus, the perpendicularity requirement could not be easily met at high latitudes. At HF frequencies, however, refraction of the radar wavevector is greater, and this allows for the perpendicularity requirement to be met at high latitudes. Refraction of radio waves in the ionosphere is a complicated non-linear phenomenon governed by the Appleton–Hartree equation. In 1983, a steerable-beam HF radar with 16 log-periodic antennas began operations at Goose Bay, Labrador, Canada.〔 Comparing measurements of F region ionopheric plasma velocity from the Goose Bay radar with the Sondestrom Incoherent Scatter Radar revealed that the Goose Bay radar was capable of measuring the F region plasma convection velocity. A magnetically conjugate radar was constructed in Antarctica at Halley Research Station in 1988 as part of the Polar Anglo–American Conjugate Experiment (PACE). PACE provided simultaneous conjugate studies of ionospheric and magnetospheric phenomena.〔 From PACE, which was only able to determine a single component of the 2D ionospheric velocity, it became apparent that determining the 2D ionospheric velocity would be advantageous. Combining velocity measurements from Goose Bay with a second coherent-scatter radar in Schefferville in 1989 allowed for a 2D determination of the F region ionospheric velocity. This work led to SuperDARN, a network of HF radars with pairs of radars having overlapping fields of view. This arrangement allowed for the determination of the full 2D ionospheric plasma convection velocity. Due to the advancement of data assimilation models, radars recently added to the network do not necessarily have overlapping fields of view. Using data from all SuperDARN radars in the northern or southern hemisphere, an ionospheric plasma convection pattern—a map of high-latitude plasma velocity at F region altitudes (300 km)—can be determined.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Super Dual Auroral Radar Network」の詳細全文を読む スポンサード リンク
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