The theoretical and experimental results of studies of the solar terminator as a source of inhomogeneous atmospheric structures are analytically reviewed. A classification of the mechanisms by which waves and atmospheric irregularities are generated is presented and briefly described. Several urgent problems related to further studies of the solar terminator and effects created by it in the near-Earth space are considered.

A statistical analysis of the variations of three components of the Earth’s magnetic field obtained at Almaty during 2008 is performed. It is found that in the daytime and nighttime periods, a distinct difference in the spectra of variations with periods corresponding to acoustic-gravity waves is observed. An explanation of this difference is proposed. It is based on the mechanism of change in the acoustic-gravity wave spectrum caused by the interaction of atmospheric gas with solar radiation.

The large amount of data that are available for ionospheric studies using the GPS TEC method, as well as the need to take into account complex atmospheric dynamics, create certain difficulties in automating the process of searching and recognizing traveling ionospheric disturbances generated by different sources. To automate the process of detecting wave disturbances, numerical criteria for assessing the level of the wave disturbance signal were proposed. The signal-to-noise ratio calculated by the proposed method was used as one of such criteria. This work contains a description of the developed software system that implements the proposed methodology and allows the loading of RINEX files and processing, analyzing, and visualizing total electron content data.

Detecting and localizing transient regime transitions in nonlinear and nonstationary time series remains a major challenge in monitoring and forecasting the behaviour of complex natural and engineered systems. In this work, we formalize and evaluate the D-index (Dynamic Energy Redistribution Index) as an energy-based dynamical diagnostic that quantifies the normalized temporal rate of change of an energy-like functional of a signal. The D-index is conceptually motivated by a quantity originally introduced within structured-systems mechanics to characterize irreversible internal energy production, but is used here strictly in an operational sense for empirical signal analysis. Rather than replacing probabilistic complexity measures derived from Shannon’s information theory, the D-index provides a complementary, energy-aware perspective by revealing localized activation and relaxation phases, burst-like episodes, and transient regime shifts that may remain weakly expressed in probability-based entropies. A computational framework with adaptive window selection is developed to ensure applicability across multiple temporal scales. Experiments on synthetic benchmarks and real observational data, including GOES x-ray flux and GNSS-derived vertical total electron content (VTEC), demonstrate that the D-index reliably identifies transitions between operating regimes, phase-change intervals, and ionospheric responses to solar terminator forcing while remaining robust to moderate and even severe noise contamination. These results confirm the practical value of the D-index as a diagnostic indicator for nonstationary signal analysis, with direct relevance to operational monitoring, early-warning detection, and predictive analytics in complex systems.

EPJ Web of Conferences, open-access proceedings in physics and astronomy