Wave activity, F1-layer disturbance and a sporadic E-layer over EISCAT

摘要: Abstract During July 1987 the EISCAT radars were used to study thin layers in ionospheric E -region. This paper outlines observing campaign, describes GEN-type radar program for UHF experiments, and discusses ‘descending’ or ‘sequential’ layer observed on afternoon of 12 during a period strong wave activity, which could be traced throughout whole - F 1 transition region. Following descent one particularly marked wave, developed around 120 km height lasted about 100 min, with temporary disappearances periods upward motion related variations field aligned ion velocity, particular ‘convergent nulls’ velocity profile. The was eventually dispersed by rapid surge velocity. Composition analysis shows that contains both long-lived light ions heavy ions, most probably Fe + .