On the probable ionospheric origin of a strong scintillation in solar radio flux records

During the late meter-decameter continuum emission of a solar type IV radio burst, a strong and broadband scintillation of solar radio flux was observed at Tremsdorf Observatory from 234 MHz - 64 MHz immediately before the SSC of the strong geomagnetic storm of February 6 - 8, 1986. Such signals have been sometimes recorded during solar continuum bursts. Arguments are shown that in the present case this phenomenon is not of solar origin but could be induced by a drifting electron density disturbance being with 20 percent in contrast to the background in the ionospheric F layer. Scattering and interference by this sharp density contrast are invoked as a cause of the observed intensity pattern.