The Super Dual Auroral Radar Network (SuperDARN) is an international radar network for studying the upper atmosphere and ionosphere, comprising eleven radars in the northern hemisphere and seven in the southern hemisphere that operate in the High Frequency (HF) bands between 8 and 22 MHz. The radars measure the Doppler velocity of plasma density irregularities in the ionosphere.
In their standard operating mode each radar scans through 16 beams of azimuthal separation 3.24°, with a total scan time of 1 min. Each beam is divided into 75 range gates of length 45 km, and so in each full scan the radars each cover 52° in azimuth and over 3000 km in range, an area of over 4×106 km².
SuperDARN began in 1983, when the first radar installation was constructed in Labrador, Canada. Source: Wikipedia
John's Hopkins Applied Physics Lab
Virginia Tech SuperDARN
CEDAR: Ground Based Instruments
SuperDARN - A Global View of the Dynamics of High-Latitude Convection