Том 63, № 2 (2023)

На основе данных медиан электронной концентрации максимума F2-слоя NmF2 пары ионосферных станций Боулдер–Хобарт за 1963–2013 гг. проведен анализ зависимости локального индекса годовой асимметрии R от местного времени и солнечной активности, где индекс R – отношение январь/июль суммарной концентрации NmF2 (для этой пары станций) в фиксированное местное время. В качестве индикатора солнечной активности для медианы NmF2 использован индекс F – среднее за 81 день значение потока радиоизлучения Солнца на длине волны 10.7 см, которое центрировано на середину данного месяца. Получено, что в зависимости индекса R от местного времени LT преобладает полусуточная мода с максимумами вблизи полудня и полуночи и минимумами утром и вечером. Самые низкие значения R = 1 наблюдаются при низкой солнечной активности в узком интервале 19.0–19.5 LT. Годовая асимметрия в медиане NmF2 существует (R > 1) для всех остальных часов местного времени при любом уровне солнечной активности. Вблизи полудня индекс R увеличивается с солнечной активностью с тенденцией к насыщению при высоком уровне этой активности. Вблизи полуночи в зависимости индекса R от F наблюдается максимум для F = 140, при превышении которого R уменьшается с ростом F. Высокие значения индекса R в полдень и полночь, в основном, обусловлены относительно высокими значениями NmF2 в январе в Cеверном полушарии (местной зимой, Боулдер) в полдень и в Южном полушарии (местным летом, Хобарт) в полночь.

A study was made of simultaneous observations of ultra-low-frequency oscillations in the 0.1–
5.0 Hz frequency range of the serpentine emissions type (Serpentine Emissions, SE) observed at the polar cap
region and disturbances in the auroral zone. The unique analog magnetic records of the Vostok Antarctic
Observatory (corrected geomagnetic coordinates Φ' = –85.41°, Λ' = 69.01°) have been digitized with a high
frequency (20 Hz) and are freely available on the website of the World Data Center for Solar-Terrestrial Physics,
Moscow. For 1966 (November and December), 1968 (March–July), and 1970–1972, 1973 (January–
March) the behavior of “serpentine emissions” was analyzed during the development of 180 isolated substorms
identified by variation in AL indexes. An interruption in the mode of generation of serpentine emissions
in the region of the polar cap was found during the active phase of intense isolated substorms (with a
maximum magnitude of the AE index of ∼500–600 nT). During the expansion phase of the substorms, broadband
noise electromagnetic radiation appears with a sharp leading edge in the PC1–2 range and is also
recorded in the polar cap. Noise radiation has a sharp leading edge and occurs approximately 2 hours after
reorientation of the bz-components of the interplanetary magnetic field (IMF) from north to south. The time
of the interruption of SE coincides with the beginning this radiation and moment of achievement bz-component
of maximum negative IMF values. Interruption of the SE effect is observed against the background of
relatively stable other geoeffective parameters of the solar wind and IMF. The average duration of the interruption
of emissions is ∼3 hours. Indirect confirmation of the impact of substorm activity on the SE generation
regime is found in the coincidence of the patterns of daily and seasonal variation of SE interruption intervals
and the probability of observing substorms. Due to the fact that noise emission occurs during the active
phase of isolated substorms and ∼2 hours after reorientation of the bz-components of the IMF in the solar
wind, there is reason to believe that it is associated with plasma flows directed towards the Earth from the
magnetotail. Apparently, the energy of plasma flows during the active phase of a substorm stimulates the
appearance of noise radiation, thus interrupting SE.

Various types of fine structure in the continuum emission of type-IV radio bursts are considered as
applied to different types of radiation sources, both stationary and moving. In the case of stationary sources,
the origin of the fine structure is associated both with processes in individual magnetic loops (quasi-periodic
acceleration and magnetohydrodynamic waves), and with large-scale processes associated with the propagation
of magnetohydrodynamic disturbances, the formation of loop arcades, and processes of discrete acceleration
of particles synchronous with them, causing the pulsating nature of radio emissions. For the case of a
moving source, the generation mechanism largely depends on the magnetic structure of the source (an
expanding magnetic arc or an isolated plasma cloud). In this case, the connection with coronal mass ejections
and shock waves is also important. Secondary pulsations are explained by a magnetohydrodynamic fluctuation
source in the form of a magnetic loop or cloud. The absence of other fine structures in the continuum of
moving type-IV bursts may be due to the critical angle of the loss cone for the excitation of whistlers

The global response of the ionosphere to intense geomagnetic storms and variations of the solar
activity according to the solar flux F10.7 is considered. As a source of information, data on total electron content
(TEC) calculated from measurements of the global network of receivers of the global navigation satellite
systems are used. Unlike many publications, where the effects of individual unique geophysical events are
studied in detail (for example, the superstorm of October 28, 2003), we considered the effects of strong storms
(Dst ≤ –80 nT) starting from 2005. The main attention was paid to the dependence on the onset time of the
main phase of the storm relative to local time/longitude, as well as the dependence of the intensity of the ionospheric
response on latitude. To display the ionospheric effects of magnetic storms, a visual image was used – a
two-dimensional representation in the day-local time format, which was used to visualize ionospheric earthquake
precursors. This approach also makes it possible to visualize the effects of solar activity variations according
to the F10.7 index and to distinguish them from ionospheric variations during geomagnetic storms. As a
result, it was possible to create a generalized global “pattern” of a geomagnetic storm in the Earth’s ionosphere

Day-to-day variations of deviations of integral daily characteristics of the sporadic E layer in different
seasons in 1987, 1996, 2003–2004, and 2014 from the reference values are investigated. The analysis is
conducted based on hourly measurements from Japanese ground-based vertical ionospheric sounding stations
in order to identify possible short-term ionospheric precursors of crustal (surface) earthquakes with
magnitudes M ≥ 6.5 under real observational conditions. Using the coincidence of the maxima in the variations
of the considered Es characteristics at the same day on pairs of stations located hundreds of kilometers
from each other, 12 possible ionospheric earthquake precursors (true alarms) and 22 false alarms, which are
not followed by earthquakes of the specified range in different seasons of 1987, 1996, and 2003–2004, were
found. The efficiency of identifying possible short-term ionospheric precursors of strong earthquakes is
determined by the chosen method based on Hanssen–Kuipers score (Rscore), which turned out to be 0.82 for
the specified time periods. It is concluded that the proposed methodology for identifying short-term ionospheric
precursors of strong earthquakes can be used in real conditions

The possibility of predicting the function of the time dependence of the sunspot number (SSN) in
the solar activity cycle is analyzed based on the application of the Elman artificial neural network platform to
the historical series of observational data. A method for normalizing the initial data for preliminary training
of the ANN algorithm is proposed, in which a sequence of virtual idealized cycles is constructed using scaled
duration coefficients and the amplitude of solar cycles. The correctness of the method is analyzed in a numerical
experiment based on modeling the time series of sunspots. The intervals of changing the adaptable
parameters in the ANN operation are estimated and a mathematical criterion for choosing a solution is proposed.
The significant asymmetry of its ascending and descending branches is a characteristic property of the
constructed functional dependence of the sunspot number cycle. A forecast of the time course for the current
25th cycle of solar activity is presented and its correctness is discussed in comparison with other forecast
results and the available data of solar activity status monitoring