Radar interferometric imaging studies of long‐duration meteor echoes observed at Jicamarca

A large number of long‐duration (≥15 s) meteor echoes were detected at the Jicamarca Radio Observatory on two nights in early August 1990 during an evening electrojet experiment. Using an interferometric imaging technique, we were able to measure a zonal velocity profile for each meteor trail. Our analysis procedure differs from conventional meteor wind methods in that it provides instantaneous profiles rather than long‐term average information. Significant altitudinal and temporal variabilities of the horizontal velocities were noted. Zonal speeds of up to 100 m s−1, large vertical shears of up to 20 m s−1/km, and rapid temporal variations of up to 50 m s−1 over an hour interval were observed. Spectral analysis indicates the presence and decay of asymmetrical high‐frequency signal components. Possible explanations for the observed high‐frequency components are discussed as are the angle of arrival of and the scattering mechanism responsible for the meteor echoes.