Nizhny Novgorod scientists have found a way to improve the accuracy of monitoring the lower ionosphere

(ORDO NEWS) — Scientists of the Scientific Research Radiophysical Institute (NIRFI) of Lobachevsky State University have developed a new method for determining the electron concentration in the E-layer of the Earth’s ionosphere.

This is one of the main parameters that determine the process of propagation of radio waves. Information about the electron density makes it possible to predict the conditions for the propagation of radio waves, analyze the effects of powerful radio emission on the Earth’s ionosphere, and study its characteristics in dynamics.

The research was supported by the Russian Foundation for Basic Research and the Russian Science Foundation. A new method for determining the electron concentration is implemented on the heating stand SURA – a multifunctional complex for the study of near-Earth and outer space . The object is one of the unique scientific installations of the Russian Federation.

The heating stand, consisting of three shortwave transmitters and a phased antenna array of 144 elements, radiates powerful radio waves at the zenith. Under their influence in the ionosphere in the altitude range from 50-60 to 250-350 kilometers, artificial periodic inhomogeneities (IPI) of the ionospheric plasma are formed, that is, inhomogeneities in temperature and electron density.

Nizhny Novgorod scientists have found a way to improve the accuracy of monitoring the lower ionosphere 1

Scientists have proposed a new formula that determines the electron density by measuring the characteristics of radio waves scattered by these irregularities in the ionospheric plasma. The development allows to determine the concentration of electrons in the area of ​​90-130 kilometers, the so-called E-layer of the ionosphere. This area of ​​heights is the least accessible for other methods.

One of the authors of the study, a leading researcher at the Department of Radio Wave Propagation and Remote Sensing, Natalia Bakhmetyeva, explains: “The method we have developed provides high measurement accuracy and altitude-time resolution. The error in determining the electron density is no more than 5-10 percent, and for example, the error of the ionospheric models widely used in the analysis of radio wave propagation can reach 30 percent.

The time resolution of the method is 10-15 seconds, the height resolution is about one kilometer. This means that every 10-15 seconds we get a height profile of the electron concentration with a height step of one kilometer. These are very good numbers.”

Unlike the upper layers of the ionosphere, the lower layers – in the altitude range of 50-150 kilometers – have not been studied in such detail. Today, the study of this part of the atmosphere is one of the main tasks of the physics of the ionosphere and space plasma.

This is a transitional region where the interaction of the thermosphere, which is regulated by solar activity, and the troposphere, which forms the weather and climate, takes place. Movements of neutral gas at these altitudes can distort missile trajectories. Here there is a strong deceleration of spacecraft, which, in turn, also perturb the natural state of the ionosphere.

Nizhny Novgorod scientists have found a way to improve the accuracy of monitoring the lower ionosphere 2

Lobachevsky University scientists received a patent for the invention “Method for determining the height profile of electron concentration” in 2021.

This development continues the series of projects of the NIRFI UNN to determine the parameters of the ionospheric plasma using artificial periodic inhomogeneities (IPI) created by the powerful radio emission of the SURA facility. Nizhny Novgorod scientists discovered this physical phenomenon in the late 1970s.

Since then, research using PPIs has continued to evolve. Among the projects of recent years: studies of atmospheric turbulence in the region of altitudes of 60-90 kilometers; development of a method for studying the ionic composition in the sporadic layer E – a layer with an increased electron concentration, a method for studying diffusion phenomena in the lower ionosphere, and others. These studies also have patents.

Nizhny Novgorod scientists have found a way to improve the accuracy of monitoring the lower ionosphere 3

In 2014 and 2018, employees of the NIRFI and the Faculty of Radiophysics carried out studies of the ionosphere by creating artificial periodic irregularities at the HAARP heating facility (USA) and at the Arecibo radio observatory (Puerto Rico).

Recall that the SURA stand is the only research center in the world for studying the interaction of high-power radio waves with ionospheric and near-Earth plasma, located in middle latitudes. In 2020, with the support of the Ministry of Education and Science, a project was launched to modernize the installation.

The modernization will contribute to the trouble-free operation of the SURA heating facility with stable high-power radio wave radiation parameters, as well as to the integrated use of the developed methods for monitoring the ionosphere.


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