Spectral-polarization analysis of interval of pulsations of diminishing periods (IPDP), observed on November 9, 2017 at Istok observatory have been carried out. Pulsation characteristics calculated from five-minute sets of magnetic data are compared with changes in the intensities of 486.1, 557.7, and 630.0 nm emissions in the north, south, east, west, and zenith directions as well as with all-sky camera images and keograms made at the same wavelengths. It is shown that the frequency of the pulsations increased when regions of the intensified emissions expanded toward the equator. A possible relationship between the appearance of east-west elongated auroral arcs and the IPDP spectral composition is considered.
We present a method to determine spatial distribution of the ionospheric electron density based on data of vertical (VS), oblique (OS), and backscatter (BS) sounding with a continuous chirp signal. Initial data represent the results of automatic processing and interpretation of ionograms, from which we calculate the height-frequency characteristics (HFC) of vertical sounding in the points selected on the sphere. From HFC tracks, we determine the ionospheric parameters and calculate the electron density profiles. This allows reconstruction of electron density spatial distribution within the sector of backscatter sounding and the region of HF radio paths. The resultant ionospheric parameters are used to correct ionospheric model IRI.
Using data of the network of chirp sounding radio paths at middle and subauroral latitudes of the Asian region of Russia, we investigated peculiarities of manifestation of medium-scale traveling ionospheric disturbances (MS TIDs) over the Asian region of Russia during solar cycle 24. Typical seasonal dependencies and daily variations in probability of MS TID occurrence and their registration time on one hop radio paths of different directions have been revealed.
On the base of oblique sounding data from three paths located in Siberia and the Russian Far East, we analyzed probability of sporadic layer occurrence during stratospheric warmings in 2009–2013. The probability of sporadic layer occurrence has been shown to increase during stratospheric warmings, especially in years of low solar activity.
The results of signal shape study for backscatter ionosphere sounding (BS) depending on conditions of radio waves propagation and electric properties of earth surface are given. The experimental BS data obtained in different seasons of the year on the basis of multifunctional chirp ionosonde developed in ISTP SB RAS were analyzed. For analysis and interpretation of BS signals on ionograms the modeling results of chirp signal characteristics under backscatter ionosphere sounding in the framework of waveguide approach were used. The most characteristic types of ionograms were identified and conditions for the appearance of one or another type were established depending on the time of day, the season, the direction of sounding and the medium state.
The methods for determining and correction of ionosphere parameters by real-time data of vertical and backscatter data sounding (VS and BS) by continuous chirp signal are presented. The input data are forecast ionosphere parameters and processing and interpretation results for VS and BS ionograms: VS height-frequency characteristic (HFC) and the leading edge of backscatter signal. On the base of the leading edge of BS signal one can calculate VS HFC for given points on the sphere in the sounding sector. On the base of HFC tracks the counting of ionosphere parameters is carried out. On the base extrapolation of the ratio of real to forecast values of ionosphere layer critical frequencies with account of layer geometrical parameters the correction of ionosphere parameters in given sphere points is carried out.
The paper presents a comprehensive algorithm to calculate characteristics of backscatter signals (BS) within the waveguide approach. The algorithm input parameters are profiles of electron density and effective frequency of collisions that are calculated from IRI model, electric parameters and the earth surface scattering coefficient. Based on the comprehensive algorithm, one can calculate amplitude characteristics of BS signals, including the signal time base using angular coefficients of radio wave scattering from rough surface. Simulation is performed for given two-way antenna-feeders. We implemented real-time algorithms to determine the BS signal leading edge and the skip zone border. Results of simulating signal characteristics are used to analyze and interpret BS ionograms obtained from the chirp ionosonde of the Institute of Solar-Terrestrial Physics SB RAS.
KEYWORDS: Backscatter, Wave propagation, Diagnostics, Data modeling, Data processing, Signal processing, Image processing, Image compression, Data compression, Interference (communication)
We present techniques and algorithms for processing and interpretation of backscatter ionosphere sounding ionograms received on chirp ionosonde. The processing of experimental ionograms is carried out on the basis of basic data filtration with the subsequent compression by method of the cellular automaton. The interpretation technique for ionograms is based on use of modeling results for frequency dependences on the minimum group way in the mode of the long-term forecast and results of experimental data processing. We also present the results of operative diagnostics of HF radio channel on the base of current backscatter sounding data.
On the base of the space-distributed multipurpose chirp ionosonde effects of solar flare influence on conditions of HF signals distribution in the northeast region of Russia were registered on February 25, 2014. The absorption increase in D – ionosphere areas during flare due to splash in x-ray radiation was shown in disappearance of the signals corresponding to modes with multiple reflections from ionospheric layer both for the ionograms of oblique and vertical sounding. In the period of a magnetic storm on February 27, 2014 on the oblique sounding ionograms on paths Magadan – Irkutsk and Khabarovsk – Irkutsk in evening and night hours of local time, were observed additional signals with abnormally big delay. The amplitude relief of abnormal signals was characterized by strong diffusion, and frequencies exceeded the maximal observed frequencies of standard propagation modes.
KEYWORDS: Solar radiation models, Solar processes, Wave propagation, X-rays, Ionization, Radio propagation, Absorption, Data modeling, Atmospheric physics, RF communications
The results for modeling of HF radio waves propagation characteristics are given for the periods of solar flares 25.02.2014, 25.10.2013, 13-14.05.2013. The distance–frequency and amplitude-frequency propagation characteristics are calculated on the base of the complex algorithm which includes modules of ionosphere and plasmasphere global models and radio waves propagation model. The results of calculations were compared with experimental data of oblique ionosphere sounding obtained by chirp ionosonde on paths Magadan – Irkutsk, Khabarovsk – Irkutsk and Norilsk – Irkutsk.
We study variation in the ionogram trace at a change in the propagation range. Addressed are the signatures of traveling ionospheric disturbances on ionograms.
KEYWORDS: Magnetism, Micro optical fluidics, Wave propagation, Radio propagation, Magnetosphere, Solar processes, Plasma, Atmospheric physics, Solar radiation models, Data modeling
The disturbances of ionospheric radio channel during 17–24 March 2015 magnetic storm are investigated. The heliospheric sources which caused the storm are considered. Based on space-distributed multipurpose chirp ionosonde data effects of geomagnetic disturbances influence on conditions of HF signal propagation are studied.
Isotropic approximation, i.e. neglect of magnetic field effects, is widely used to simplify the geometrical optics description of ionospheric propagation of radio waves. However, this description under certain conditions may produce a significant error. In this study, ray traycing is performed to examine an isotropic approximation error in relation to operating frequency and radiation angles.
The possibility of manifestation of tropical cyclones in variations of ionospheric parameters in the zone far removed from the disturbance source region has been studied. The data from frequency analysis by maximal observed frequencies (MOF) for the oblique sounding (OS) signals were used. We revealed 1–5 h time intervals with higher oscillation energetics along the Norilsk–Irkutsk, Magadan–Irkutsk, and Khabarovsk–Irkutsk paths (Eastern Siberia and the Far East of Russia) during equinoctial periods (March, September 2005–2011), in November, 2005 and in summer 2010-2011 for different periods of the solar cycle. These time intervals may be interpreted as a manifestation of large-scale traveling ionospheric disturbances (TIDs) whose sources are atmospheric internal gravity waves. By jointly analyzing ionospheric, heliomagnetic, atmospheric, and satellite data on tropical cyclones (TCs), we attempted to associate the series of the revealed TIDs with ionospheric responses to TCs over the Western North Pacific Ocean during the above periods. A significant increase in wave disturbances on OS paths was established to be noted during active tropical cyclogenesis periods in autumn months. For spring equinox (March, 2005–2011), we also note TID manifestations in MOF time variations under quiet heliomagnetic conditions and in TC absence, but the intensity of these wave disturbances was significantly lower, than that of autumn seasons for various years. We estimated the wavelike disturbance propagation velocity by the delay time of TID passing the medium points of the spaced OS paths.
Oleg Berngardt, Victor Grozov, Nikolai Ilyin, Vladimir Kurkin, Andrey Medvedev, Sergei Ponomarchuk, Konstantin Ratovsky, Boris Shpynev, Alexander Voronov
We present a solid information system for storing, accessing and collecting of Earth upper atmosphere sounding data
produced by radiophysical instrument complex of Institute of Solar-Terrestrial Physics SB RAS. At present complex
consists of Irkutsk incoherent scatter radar unique in Russia, four frequency modulated current waves ionosounders
(FMCW) operating in vertical, oblique-incidence and backscattering sounding modes and two digital ionosounders
DPS-4. We suggest a technique for unification of heterogeneous data into united format and secondary processing with
unified technology based on international techniques of geophysical parameters determining. We discuss a structure of
united information system with Web access which allows us to integrate our radiophysical data into worldwide network
of geophysical data.
We present the coherent echo observation results obtained by Irkutsk Incoherent Scatter radar during September 25, 1998 ionospheric storm. It is shown that during that time we have observed scattering from irregularities elongated with Earth's magnetic field and located in the E-region of ionosphere. A good correlation between vertical component of magnetic field disturbance and logarithm of received power was found.
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