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

Abstract

We analyze the rare phenomenon of ultraenergetic relativistic electron (∼100 MeV) precipitation into the middle polar atmosphere prevalent under quiescent geophysical conditions. Such events have been established previously from ground‐based radio wave measurements for two radio paths—one is purely auroral and the other is partly auroral—that have a mutual point of signal reception. We solve an inverse very low frequency wave problem of the second type using these particular paths. The solution gives a linear scale of the northern part of radio path, which has been disturbed by the ultraenergetic relativistic electron precipitations. By such a way the effective latitudes of southern boundaries for several precipitation events, published earlier, were determined. Nearly circular shape of equatorward cutoff at ∼61°magnetic latitude without day‐night asymmetry supports that ultraenergetic relativistic electron precipitation is due to precipitation of very high energy electrons coming from outer space.

Estimation of the Mode Conversion Effect on the Determination of Southern Boundary for the ∼100 MeV Electron Precipitations

“…The same changes of complex magnitude 1 E T are comparable with the measurement errors of the experimental data used by us. Therefore, we have justified the correctness of our digital determination of the magnetic latitude of equatorward boundary of URE precipitation (Remenets & Astafiev, 2015), in which we have not used the powerful disturbances.…”

“…In the works (Remenets & Astafiev, 2015, 2016 we have determined the southern boundaries of URE precipitations which had been registered (about 300 events for 1982-1992 years with 16 powerful ones) by a VLF-method for 10-16 kHz. The method was based on continuous ground-based measurements (by the scientists of the Polar Geophysical Institute -RAS, Apatity, Murmansk reg., Russian Federation) of amplitude and phase disturbances for several VLF-signals for two radio paths: one path 1 E S with 10-14 kHz monochromatic signals was completely auroral and the second path 2 E S (United Kingdom -Kola Peninsula)…”

“…The pointed inhomogeneity of radio path is the cause of conversion of a normal wave of terrestrial wave guide at other normal waves. Having certain quantitative estimations about a significance of this effect on the base of our predecessor calculations for other types of inhomogeneity (such as an abrupt change of electric properties of ground, an abrupt one-step change of waveguide effective height) (Bahar & Wait, 1965;Osadchy & Remenets, 1979;Pappert & Ferguson, 1986;Pappert & Morfitt, 1972;Smith, 1977;Wait, 1968;Wait & Spies, 1968) we ignored the pointed effect in the publications (Remenets & Astafiev, 2015, 2016. Nevertheless, here we have to justify our previous neglect by taking into account the effect of conversion of a normal wave in other ones and to point for what type of URE precipitation (moderate, strong or powerful) it is necessary to take into account this effect while a boundary latitude calculation.…”

“…The pointed solutions were based on a theory of VLF wave propagation in near-Earth waveguide, that is, they were based on the Maxwell equation consequences for a physics model of waveguide (Gyunninen & Zabavina, 1966;Makarov et al, 1993). At one of the pointed solutions of the inverse problem the ray (′′hop′′) theory (with the Watson-Fock diffraction wave and two rays reflecting from a ′′bottom′′ of atmosphere ionized) (Bondarenko & Remenets, 2001;Remenets, 1997;Remenets & Astafiev, 2015, 2016Remenets & Beloglazov, 2013) were used. At another Abstract Previously the parameters of sporadic s E D layer of electric conductivity caused by ultraenergetic relativistic electron (URE) precipitations were determined by us due to indirect electromagnetic method.…”

“…The electric conductivity is approximated by two exponential functions for which its logarithm is a function with an ′′ knee′′ at the altitude   0 0 E z r R, (Beloglazov & Zabavina, 1982a, 1982b. This approximation corresponds to the auroral undisturbed or moderately disturbed low ionosphere, Figure 1 with the curve 1 for This statement of the simulation problem may seem to be far away from the real situation because: (a) In reality there is a second axis of symmetry connected with the geomagnetic field, which determines a circular zone of very energetic solar proton (100 MeV) (Dmitriev et al, 2010) and URE precipitations (Remenets & Astafiev, 2015); therefore, a normal wave propagating from England to Kola Peninsula is falling on the boundary of irregularity not normally, see Figure 1 in the work (Remenets & Astafiev, 2016). (b) The real radius of boundary curvature is centered at South magnetic pole, the center of model cone boundary is placed in England and its radius on earth has value…”