Geomagnetic cutoff effect as an evidence for the corpuscular nature of anomalous VLF disturbances

Abstract

The effect of geomagnetic cutoff with respect to the primary ionizing flux, which caused anoma lous VLF disturbances on a completely auroral radio path with a moderate length (~900 km), has been proved. Abnormality manifested itself in a qualitative similarity of amplitude and phase variations at all three working frequencies of this radio path. This should not be observed if the contribution of the second iono spheric ray to the received field is substantial. This similarity is still the only signature of ultrarelativistic elec tron precipitation. The VLF data for the auroral and long partially auroral radio paths with a common receiver point (10-16 kHz) in the auroral zone have been qualitatively compared in order to prove the geo magnetic cutoff effect. The experimental database on disturbances occupies six years in the vicinity of the solar activity minimum (1982)(1983)(1984)(1985)(1986)(1987). The manifestation of the magnetic cutoff in the above experimental data indicates that the primary ionizing flux is of the corpuscular nature. This flux generates X ray bremsstrahlung, which produces the ionized sporadic D S layer in the middle auroral atmosphere.

Southern boundaries of ultraenergetic relativistic electron precipitations in several cases from 1982 to 1986 years

“…However, in the papers listed above, the values of geomagnetic latitudes for the southern boundary were not given because of the absence of the corresponding VLF specific calculations that we present in this work. These values, along with the fact that the events of UREP, which we discuss here, can take place at any MLT hours (see tables in Remenets and Beloglazov [] and similar tables in Beloglazov and Remenets [] and Remenets and Beloglazov []), support the idea that an UREP can be an electron analog of a solar proton precipitation.…”

“…The purpose of this study is to give additional quantitative arguments in support of this interpretation. Earlier, we demonstrated that the phenomenon was characterized by a low‐latitude cutoff effect [ Beloglazov and Remenets , ; Remenets and Beloglazov , ], resembling the well‐known geomagnetic cutoff of the cosmic rays.…”

“…During the period 1982–1987, continuous and synchronous measurements in the polar region of the phases and amplitudes of radio signals along two radio paths were carried out [ Remenets and Beloglazov , ]. The mutual position of the receivers was in Apatity (Kola Peninsula, 67°34 ′ N, 33° 23 ′ E).…”

“…The second radio path (GBR station in the UK, 52°22 ′ N, 01°11 ′ W, at a single frequency f 4 = 16 kHz with length of radio path S 2 = 2497 km) was referred to as the “long” one, with about two thirds of its length lying in middle latitudes. The quantitative relationships existing between wave phase variations along these two radio paths during anomalous VLF events can be considered as supporting evidence for the presence of a geomagnetic field cutoff effect on the charged particle precipitation into the polar middle atmosphere and, as a consequence, for the existence of a southern boundary for such precipitations [ Remenets and Beloglazov , ].…”

“…The named VLF specific calculations are original and never used before by the investigators either for solar cosmic rays or for the electron precipitations. Therefore, the second purpose of this work is to provide new and more accurate estimates of the effective boundary between the quiescent and disturbed parts of the long radio path from the UK to Kola Peninsula in the Russian Federation and to compare these estimates with semiqualitative result given in the previous works [ Remenets and Beloglazov , ; Remenets , ; Beloglazov and Remenets , ; Remenets and Beloglazov , ].…”