UTILIZATION OF SKY-WAVE BACKSCATTER SOUNDERS FOR REAL-TIME MONITORINGOF IONOSPHERIC STRUCTURE OVER EXTENDED GEOGRAPHIC REGIONS

Backscatter ionograms (BI) and quasi vertical incidence (QVI) ionogram s are routinely collected at over-the-horizon radar (OTHR) installatio ns operated by the U.S. Navy. The BI provides information about the do wnrange ionosphere up to several thousand km from the sounder. In this paper, a method for the quantitative extraction of this information b y means of a leading edge inversion technique is described and applied to data acquired by the BI sounder operating at the Chesapeake, VA OT HR facility. Because this sounder is used to sample 8 azimuthal sector s, maps of plasma frequency at a constant altitude can be derived over a geographic region that covers a 64 degrees angular sector out to di stances of similar to 2000 km. The unique capability of the OTHR BI so unders to provide realtime monitoring of the ionosphere over a large g eographical area is demonstrated.