Fundamentals of radio-chemical physics of the Earth’s atmosphere

The Problems of Passive Remote Sensing of the Earth’s Surface in the Range of 1.2–1.6 GHz

“…It was shown [6][7][8] that, at altitudes from 60 to 110 km, the Sun flares produce a super background ultra high frequency UHF radiation with intensity hundreds of times higher the typical levels of microwave solar bursts. An analysis of the different mechanisms of generation of the detected radiation showed that the largest contribution to the resulting spectrum picture comes from the transitions between Rydberg states of the neutral components of a non-equilibrium two-temperature plasma excited by fluxes of sunlight and slow electrons penetrating in the low ionosphere [1][2][3][4]. Incoherent UHF radiation from Rydberg states during geomagnetic disturbances is accompanied earlier by an intense long-wave infrared (IR) radiation (with the wavelength exceeding 15 µm) [9].…”

“…Passive remote sensing involves the use of natural radiation to determine the properties of the Earth's surface, which is usually carried out with receivers operating at a frequency of 1.4 GHz, since, at this frequency, there is a single-parameter dependence of the signal power on the electron concentration [3]. There is still no unique physical understanding among specialists regarding the source of radiation at a frequency of 1.4 GHz [2]. It was previously assumed that this source has a cosmic origin and it corresponds to the radiation of a hydrogen line with a wavelength of 21 cm and a transition frequency ν = 1.4204 GHz, corresponding to an energy of 5.86 10 −6 eV [10].…”

“…A large number of original articles, reviews, and monographs are devoted to the remote sensing of the Earth's surface (see, for example, the lists of publications in [1,2]). However, these publications do not take the delay in the propagation distortion of radio waves as a result of resonant scattering during the passage of D and E layers of the ionosphere at an altitude of 60-110 km into account [7].…”

“…However, these publications do not take the delay in the propagation distortion of radio waves as a result of resonant scattering during the passage of D and E layers of the ionosphere at an altitude of 60-110 km into account [7]. In addition, they do not take into account both a direct super background microwave radiation coming to the satellite from the D and E layers of ionosphere and the signal attenuation due to the interaction with charged aerosol layers [1][2][3].…”

“…Currently, considerable interest is given to the physicochemical processes, with the participation of electronically excited states taking place in the lower ionosphere of the Earth, which is primarily associated with the problems of remote passive location of the Earth's surface [1][2][3]. A spontaneous increase in solar activity accompanied by a significant increase in electromagnetic radiation leads to noticeable perturbations of the propagation medium.…”