卷 57, 编号 3 (2017)

An algorithm for retrieving the AL index dynamics from the parameters of solar-wind plasma and the interplanetary magnetic field (IMF) has been developed. Along with other geoeffective parameters of the solar wind, an integral parameter in the form of the cumulative sum Σ[N*V²] is used to determine the process of substorm formation. The algorithm is incorporated into a framework developed to retrieve the AL index of an Elman-type artificial neural network (ANN) containing an additional layer of neurons that provides an “internal memory” of the prehistory of the dynamical process to be retrieved. The ANN is trained on data of 70 eight-hour-long time intervals, including the periods of isolated magnetospheric substorms. The efficiency of this approach is demonstrated by numerical neural-network experiments on retrieving the dynamics of the AL index from the of solar wind and IMF parameters during substorms.

We have studied the influence of daytime polar substorms (geomagnetic bays under the IMF Bz > 0) on variations of the vertical gradient of the atmospheric electric field potential (Ez) observed at the Polish Hornsund Station (Svalbard, Norway). Only the observations of Ez under “fair weather” conditions were used, i.e. in the absence of strong wind, precipitations, low cloud cover, etc. We studied more than 20 events of daytime polar substorms registered by the Scandinavian chain of IMAGE magnetometers in 2010–2014 during the “fair weather” periods at the Hornsund Station. Analysis of the observations showed that Ez significantly deviates from the its background variations during daytime, as a rule, when the Hornsund Station is in the region of projection of the daytime auroral oval, the position of which was determined from OVATION data. It was shown that the development of a daytime polar substorm leads to fluctuating enhance of Ez values. It was found that Ez surges are accompanied by intensification of field-aligned electric currents outflowing from the ionosphere, which were calculated from the data of low-orbit communication satellites of the AMPERE project.

The structure and dynamics of ion-acoustic waves in an unmagnetized plasma, including the case of weakly relativistic collisional plasma (when it is necessary to take into account the high energy particle flows which are observed in the magnetospheric plasma), are studied analytically and numerically on the basis of a model of the Kadomtsev-Petviashvili (KP) equation. It is shown that, if the velocity of plasma particles approaches the speed of light, the relativistic effects start to strongly influence on the wave characteristics, such as its phase velocity, amplitude, and characteristic wavelength, with the propagation of the twodimensional solitary ion-acoustic wave. The results can be used in the study of nonlinear wave processes in the magnetosphere and in laser and astrophysical plasma.

This paper investigates preearthquake ionospheric variations with the use of TEC of Global Ionospheric Maps (GIMs) and regional maps based on Precise Point Positioning (PPP) during the 7.1-M Indonesian earthquake that occurred on November 15, 2014. TEC maps corresponding to 10 days before to 4 days after the event were examined. In addition, a time series of TEC values according to the PPP maps were also evaluated. In addition to GIMs, it was possible to detect TEC variations with PPP maps. The results showed that ionospheric TEC decreased strikingly 4 days prior to the earthquake. This TEC variation was highly likely related to seismic activity.

The method of study of magnetically oriented ionosphere inhomogeneities based on the analysis of radar decametric emission backscattering on inhomogeneities is proposed. It is shown that certain conditions, including the orientation of the propagation route relative to the Earth’s magnetic field lines and the polarization and frequency of the emitted wave, make possible resonant backscattering of radiolocation system emission on magnetically oriented ionosphere inhomogeneities. The paper presents the results of experimental observation of scattering in Kamchatka Peninsula. They demonstrated the opportunity to evaluate the extension of the scattering region, the vertical and horizontal components of the velocities of magnetically oriented inhomogeneities, and the frequency dependence of these parameters.

Data on observations of acoustic gravity waves and variations in the electric field strength in the surface layer of the atmosphere are presented. Analysis of the obtained data shows that synchronous variations in the pressure and electric field strength appear with the passage of a weather front, solar terminator, and in some other cases. It is seen that the amplitude of electric field perturbations is approximately proportional to the amplitude of variation in the pressure. A possible mechanism of generating electric field perturbations during the passage of microbaroms has been considered.

The maximum achievable parameters of magnetometers based on optomechanical quartz variometers are studied in connection with the planned transition of the international network Intermagnet to 1-s recording and the need to provide the network of Russian geomagnetic observatories with domestic magnetometers that satisfy Intermagnet requirements. The mechanism of negative feedback effect on the sensitivity threshold of a variometer with an optoelectronic angle transducer is shown. The optimization criterion for the size and shape of the magnets made of different magnetic materials is defined by the maximum ratio of the magnetic moment to the inertial moment. Theoretical and experimental evaluation of the variometer noise level is based on vicalloy and samarium–cobalt. It is shown that the frequency range of magnetometers with variometers based on vicalloy and samarium–cobalt will be bounded from above by frequencies of 1.6 and 6.4 Hz, respectively, at a threshold sensitivity of about 1 pT. These ratios of the frequency and threshold sensitivity for the given magnetic materials are probably limited for quartz variometers with an optoelectronic angle transducer.

We considered two types of magnetic field time asymmetry related to the inverse influence of the magnetic field on the currents in the dynamo models and observations. The first type includes variations in which the total time that the time derivative is positive is different from the time that this derivative is negative. In a monochromatic wave, this corresponds to a failure of symmetry with respect to the point at which the wave has an extremum. The second class includes the time signals at which another failure of antisymmetry appears relative to the mean value of the signal. None of these types of symmetry can be recorded by the methods of the Fourier or wavelet analysis. We use the Parker’s dynamo model in a thin layer and a threedimensional model in a flat rotating layer when heated from below and present estimates of the failure of the symmetry data. It was shown that in the paleo-variations the model time of field increase is smaller than the time of its decrease.