Radar Studies of the Equatorial Ionosphere

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The echoes seen by high frequency radars consist of intense "coherent" signal returns from "irregularities" in the ionosphere and weak "incoherent" returns from the background thermal structure of the plasma. The latter echoes give the plasma concentration, composition, electron and ion temperatures, and are due to plasma waves from a variety of sources, including electrical currents flowing through the plasma and gravity waves propagating through the neutral atmosphere. A thin layer of echoes seen at mid-latitudes and now at the equator has not been explained. The irregularities cause distortion and interference in short wave radio communication, and in ground to satellite communication links. This award is for radar studies at the Jicamarca Observatory in Peru. Measurements will be made of irregularities and waves in the Mesosphere (50-85 km altitude) and in the Lower Thermosphere (85-120 km altitude) to better understand the nature of the mechanisms producing them.