High-frequency radar

{
  "id": "MLC-T-MET-006251",
  "term": "High-frequency radar",
  "field": "Meteorology and atmospheric science",
  "definition": "A remote sensing system that uses radio waves in the high-frequency band (3 to 30 MHz) to measure the speed and direction of ocean surface currents. The radar signals are transmitted over the horizon and scatter off ocean waves, with the Doppler shift of the returned signal indicating the underlying current velocity. A network of these radars can map surface currents over broad coastal areas, extending up to 200 kilometers offshore.",
  "see_also": [
    "Doppler radar",
    "marine radar",
    "microwave radar",
    "synthetic aperture radar"
  ],
  "url": "https://mlchart.com/terminology/meteorology/high-frequency-radar/"
}