Pleiades Publishing Ltd

Data from the BMSW spectrometer, which measures the ion flux value and sometimes plasma parameters with a time resolution of 31 ms, allow the study of the parameters of turbulence of the solar wind and magnetosheath plasma on kinetic scales. In this work, the frequency spectra of the ion flux fluctuations before and after recording the interplanetary shock front in the Earth’s magnetosheath are compared based on these data. It is shown that, in contrast to the solar wind, where the exponential decay of the spectrum often occurs after the shock front on the kinetic scales, no such phenomenon is observed in the magnetosheath: the spectrum on these scales can be approximated by a power function in all the cases considered. In half of these cases, the spectrum slope on the kinetic scales does not change during the interplanetary shock propagation. The results indicate a weak impact of interplanetary shock waves on the parameters of the plasma turbulence. In addition, it is shown that an interplanetary shock does not change the level of intermittency of the ion flux in the magnetosheath at both low and high level before the front.

Observations of interplanetary scintillations of the 3C 298 and 3C 48 radio sources during low solar activity, performed with a BSA FIAN radio telescope at a frequency of 111 MHz, are presented. The radial dependences of the scintillation indices, where the effect of a low-latitude heliospheric current sheet is observed, have been obtained. Based on the scintillation temporal spectra, the solar wind velocity values have been obtained, and it has been indicated that these values are in good agreement with those found using the spaced measurements method.

A mathematical modeling method and the global numerical model of the Earth’s upper atmosphere were used to study nighttime enhanced electron density regions (EEDRs) in the ionospheric F2 layer and their possible manifestations at altitudes of the Earth’s plasmasphere. It has been established that EEDRs are formed owing to latitudinally nonuniform longitudinal (along the magnetic field) plasma flows from the plasmasphere into the nighttime ionosphere and the wind transport of ions along geomagnetic field lines. The specific features of the effect of ionospheric-plasmaspheric plasma transport processes, related to their three-dimensional character, on EEDRs have been revealed.

The descent and ejection of matter in the solar atmosphere observed in the CaII 8498-Å line have been studied. In the NOAA active region no. 10 792 on July 30, 2005 before the flare, the dense cold gas cloud descended with a ray velocity of ∼8 km/s and then ascended in the impulsive phase. The plasma ascended with an acceleration reaching 0.4 km/s2 in the flare maximum. The acceleration of the matter likely continued after the flare maximum, because an acceleration of higher than 0.5 km/s2 was required for the appearance of the ejection at the edge of the occulting disk of the LASCO C2 coronagraph at 0557 UT. The descent of the matter resulting in the local heating of the chromosphere was also observed in the NOAA active region no. 10656 on August 9, 2004 before the flare. The maximum descent velocity was no more than 24.7 km/s.

The results of long-term mesoscale observations in the microwave range are reviewed. The rationale for the resumption of observations at the Havana Radio Astronomy Station is justified. Domestic observations at a wavelength of λ5 cm have a long observation interval and can effectively complement the global series of observations. A comparative analysis of the results of solar observation in the radio range and satellite observations in the UV and X-ray range is performed. The value of continuous observations for the assessment of space weather factors is shown.

Paleoclimatic data from a sequence of argillite deposits of the Gowganda Formation located in the Mississagi River Valley (southern Ontario Province, Canada) covering a time interval of 256 years with a time resolution of one year are studied to research possible variations of the Earth’s climate in the Paleoproterozoic (~2 Ga ago). The following quasi-periodic variations have been found via the construction of a combined spectral periodogram: 3, 5, 11, 14, 29, and 75 years (at significance levels of the respective estimated values of magnitudes ranging from 2σ to 4σ). This may indicate the possible influence of solar activity on climate changes in the geological past.

The properties of the 12-h artifact in the data of the SDO/HMI instrument (Helioseismic and Magnetic Imager) caused by the nonzero radial velocity of the station relative to the Sun are investigated. The study has been carried out with respect to long-period oscillations of the magnetic field of sunspots for different station positions in the Earth’s orbit by the alternative spectral method of singular decomposition of the signal CaterPillarSSA. Features of artifact filtering, both in special positions of the station (at the points of aphelion and perihelion) and at arbitrarily selected orbital points, are considered. It is shown that the 12-h artifact mode can be completely filtered from the time series of the observed variable, not only at these two orbital points (because of the symmetry of the station’s radial velocity with respect to the zero mean here) but also at any others. It is shown that only a 12-h mode is physically justified, while the 24-h harmonic appears only as an artifact in the Fourier decomposition of the amplitude-modulated signal. It is emphasized that the values of the magnetic field measured with SDO/HMI are sensitive only to the station’s radial velocity absolute values with respect to the Sun and do not depend on its direction. It has been noted that the periods of sunspot oscillation as a whole obtained from SDO/HMI data after orbital artifact filtration fit well into the dependence diagram of the period of sunspot oscillations on the value of its magnetic field strength constructed earlier by SOHO/MDIdata.

The paper quantitatively compares the results of calculations of the electron density Ne by the International Reference Ionosphere model IRI-2016 with experimental data obtained from the DE-2 satellite. It considers 648 variants of heliogeophysical conditions. The deviation of theoretical estimates from experimental values is within the instrumental accuracy of satellite data in an average of 27% of cases. It is concluded that the IRI-2016 model, the approximation coefficients of which in functional dependences are associated with heights of the F-region, gives negative values of the efficiency coefficient of the predicted electron density in ~73% of cases in the outer ionosphere at altitudes over 500 km.

The data of measurements of broadband wave radiation in the main ionospheric trough in the subauroral zone of the topside ionosphere in the region of the day-night terminator (APEX satellite experiment) are presented. It is shown that the observed attenuation of electrostatic radiation in a broad frequency band and fluctuations (variations) in the cutoff frequency of the electrostatic mode spectrum at the level of the local plasma or upper hybrid frequency are related to plasma heating by damping electrostatic oscillations in the ionospheric trough. Waveguide channels for propagation of electromagnetic whistler-mode waves observed on the satellite can be generated during the propagation of a gravity-thermal disturbance from the terminator.