Ultrarelativistic electrons in the near cosmos and X‐ray aurora in the middle polar atmosphere

Abstract

[1] The rare phenomenon of ultrarelativistic electron precipitation into the middle polar atmosphere, prevalent under calm geophysical conditions, was established from ground-based radio wave measurements during the period of 1982-1992. Precipitating electrons with energy 100 MeV and sufficient density to generate X-and gamma-ray bremsstrahlung create a sporadic layer of ionization in the atmosphere under the regular D layer of the ionosphere. Very low frequency radio waves reflect from this sporadic layer with abnormal weakening and with an unusually low height of reflection. The layer has a horizontal linear scale of about several thousand kilometers, with a thickness in altitude of about 20-30 km, and persists for several hours. Due to this layer of electric conductivity, the effective height of this "ground-ionized atmosphere" waveguide diminishes in exceptional cases by 2-2.5 times. The auroras of X-ray bremsstrahlung have been detected by the reflection of radio waves with wavelengths of 30-20 km. This phenomenon may be termed "a polar cap absorption effect of the second kind" as an electron analog of proton precipitation.Citation: Remenets, G. F., and M. I. Beloglazov (2013), Ultrarelativistic electrons in the near cosmos and X-ray aurora in the middle polar 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.…”

“…Precipitating electrons with such high energies (∼100 MeV) and high flux densities that generate X‐ray and gamma ray bremsstrahlung emission and create a sporadic D s layer of ionization in the polar atmosphere under the regular D layer of ionosphere have only been detected by analyzing the measurements in the very low frequency (VLF) range (3–30 kHz) of radio waves [ 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 , ].…”

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

“…Long term experimental and theoretical study of anomalous VLF radiosignal variations on a completely auroral radio path made it possible to detect a new geophysical phenomenon (Remenets and Beloglazov, 1985, 1992, 1999, 2013Remenets, 1997Remenets, , 2001Remenets, , 2005Beloglazov and Remenets, 2005). This phenomenon is not registered by traditional geophysical methods and has not yet been observed using the space measur ing technique.…”