Geomagnetic control of satellite scintillations

Satellite scintillations may be divided into three basic types: (1) low-angle scintillations of both tropospheric and ionospheric origin; (2) clouds or patches of ionization containing irregularities including sporadic E; and (3) precipitation scintillation occurring for the most part at heights of 300 to 500 km. The third type is discussed in detail; the hypothesis is advanced that this basic mechanism of auroral-zone scintillation originates in irregularities produced by precipitation of charged particles on the atmosphere, the precipitation boundary being controlled in the same manner as the aurora. The variation of scintillation index with angle of elevation is pronounced when looking north from the observatory (54°N geomagnetic) in comparison with that when looking south. During magnetic storms the irregularity structure moves to lower latitudes in much the same manner as other auroral phenomena. The use of satellite transmissions permits the separation of subionospheric geomagnetic latitudes from angles of elevation; this has not been done in most studies of radio-star sources.