Possibilities of Satellite Radio Tomography and Related Products for Studying the Ionospheric Structures in Various Geophysical Conditionsтезисы доклада
Дата последнего поиска статьи во внешних источниках: 10 июня 2020 г.
Место издания:2019 The Electromagnetics Academy. All rights reserved Rome, ITALY
Первая страница:801
Аннотация:It is known that the accuracy of the forecasts of the ionospheric propagation of radio waves is directly related to the model of natural environment assumed in the calculations. Therefore, it is extremely important that the models of the ionosphere adequately reflect the distributions of ionospheric parameters observed in the experiments. The distribution of the ionospheric parameters is determined by the combination of the highly complicated and diverse processes of solar-terrestrial interaction. During the periods of the strong geophysical disturbances, the ionosphere has extremely complex structure and vigorous dynamics; the parameters of the ionosphere rapidly and sharply vary under the influence of various factors. This requires the use of non-local methods for diagnosing the spatiotemporal structure of the ionosphere. One of the most efficient methods for achieving this objective is ionospheric satellite radio tomography (RT) which makes it possible to obtain information about the spatiotemporal structure of the ionosphere not at a single point but over a fairly large spatial interval. RT is an effective method for studying the structure of the ionosphere during the periods of strong geomagnetic storms when other methods of ionospheric sounding are impracticable due to the strong absorption of the signals or unreliable because of the reflection of waves from the irregularities.
In this work, we used two modifications of the radio tomographic methods. One is low orbiting radio tomography (LORT). LORT is based on the coherent transmissions of radio signals by the previous generation of navigational satellites such as Parus/TRANSIT received at the chains of the ground receivers installed along the satellite trajectories. This measurement scheme provides 2D height-latitude cross sections of the ionosphere. Another modification is the high orbiting radio tomography (HORT) based on the processing of GNSS signals recorded by the global and regional receiving networks. HORT yields 4D (three spatial coordinates and time) distributions of electron density in the ionosphere. LORT has a horizontal resolution of 20–30 km and vertical resolution 30–40 km. HORT has a spatial resolution of 70–100 km and a time step of 60–30 min in the regions with sufficiently dense receiving networks.
We demonstrate and discuss the examples of RT reconstructions of the ionosphere for different variations of space weather. The RT methods allow to reconstruct not only the ionospheric irregularities of natural origin but also to detect the disturbances induced by anthropogenic sources (industrial explosions, rocket launches, heating by high-power HF radiation). We also presents the results of ray tracing simulations for HF radio waves in a naturally and artificially perturbed ionosphere based on the RT data. The work was supported by the Russian Foundation for Basic Research (projects nos. 19-05-00941 and 17-05-01250).