This review paper aims at synthesizing global observations reported by Moiseev (1990), Branover et al. (1999), Kikuchi (1991, 2001), Hayakawa and Molchanov (2002); Pulinets and Boyarchuk (2004), Hayakawa (2007, 2015), Mishin and Streltsov (2022), Pulinets and Herrera (2024), and others, in order to examine the cross-domain coupling within Earth’s mantle–lithosphere–atmosphere–ionosphere–magnetosphere (MaLAIM) system. We begin with emphasizing ionospheric manifestations of heterogeneous-Earth and atmosphere processes, because the ionosphere is often the most responsive layer in the MaLAIM chain. Its plasma supports sporadic layers and multiscale irregularities that are routinely detected by ground-based and satellite instruments. We then consider how radiogenic isotopes (e.g., Rn, U, Th, etc.) decay to lighter isotopes and heterogeneous tectonic structures (faults and fractures) in the lithosphere drive gas-dynamic, electrodynamic and thermodynamic processes. These flows, together with infrasound as a lower-branch of acoustic gravity waves (AGWs) generated by near-Earth surface activity, provide efficient coupling pathways between the lithosphere and the atmosphere. The injected gases and waves modify atmospheric thermal structure and conductivity, perturbing the ionization–recombination balance and driving vertical currents into the ionosphere. The resulting forcing of the ionosphere can modulate plasma density and dynamics, producing quasi-periodic irregularities from the E region (~90–120 km) to the F2 layer (~250–400+ km), including sporadic-E and sporadic-F, traveling ionospheric disturbances, and plasma turbulence. We ground our analysis on theory and align each stage with observations, demonstrating the cross-layer coupling. Field measurements suggest radon emanation through lithospheric faults into the atmosphere, accompanied by localized warming of the atmospheric gas (~8–10 °C), ion–molecule cluster formation, and buoyancy-driven turbulent mixing of light gases. Atmospheric measurements further indicate leakage via low-frequency acoustic waves (infrasound), which commonly accompany intense weather systems (cyclones, typhoons, tornadoes). We then examine the AIM (atmosphere–ionosphere–magnetosphere) coupling mechanism in the context of earthquake precursors, following Blaunstein (2000), Blaunstein and Hayakawa (2009), and the experiments reported therein. The ionosonde records from the Vrancea seismic zone (Romania, 2008–2017) show pre-seismic ionospheric stratification consistent with theoretical expectations and previous literatures (e.g., Pulinets & Boyarchuk, 2004; Molchanov & Hayakawa, 2008; Ouzounov et al., 2018; Pulinets & Herrera, 2024). Finally, it is shown that the spectral properties of the natural clutter phenomena in various latitudes of the perturbed ionosphere – polar, northern, middle, equatorial, - can be the main of separation of the effects caused by each of them individually that can be observed experimentally with the use of ground- and satellite–based equipment.

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The present study is devoted to Schumann resonance (SR), which is the extremely low frequency (ELF) electromagnetic resonance in the Earth–ionosphere cavity due to global lightning discharges. We treat the intra-annual variations of the basic SR frequency present in the long-term observations at the Széchenyi István Geophysical Observatory (SZIGO) at Nagycenk (geographic coordinates: 47.6 N, 16.7 E) in Hungary, where the vertical electric field Er was monitored during 192 months from January 1994 to December 2009. These records are compared with the data on concurrent solar activity from the Laboratory for Atmospheric and Space Physics (https://doi.org/10.25980/L27Z-XD34). The singular spectral analysis (SSA) of these observations revealed the intra-annual and interannual principal components in the temporal variations of experimental records, and a comparison of these data allowed formulating the following results. The SSA processing of the long-term monitoring of the basic SR frequency in the vertical electric field at the Nagycenk SZIGO observatory revealed the presence of intra-annual variations of the pattern returning year after year. Similar intra-annual variations were completely absent in the concurrent solar activity. In spite of qualitative and quantitative agreements between the intra-annual patterns of SR frequency and in the distance from the Earth to the Sun, these frequency variations should be attributed to the seasonal north-south drift of the global thunderstorm activity against the equator. Thus, the intra-annual variations were not caused by the eccentricity of the Earth's orbit, but by the tilt of its rotation axis to the plane of its orbit.

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We are developing algorithms to detect temperature anomalies associated with volcanic activity, especially related to the lava effusion or lava dome formation. This paper presents a spatio-temporal statistical analysis of surface temperatures around the crater of Mt. Shinmoedake in 2018 using infrared data from the sensor Advanced Himawari Imager (AHI) with the high temporal resolution onboard the geostationary satellite Himawari-8. The preliminary results show that high singularity anomalies could be detected several hours before the first vulcanian eruption using brightness temperature data of 10 min sampling data for not only nighttime but also daytime. This preliminary study could indicate the highly suggestive of effectiveness of Himawari-8 AHI data for monitoring volcanic lava activity and rapid detection of lava effusion.

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Very low frequency (VLF) radio wave propagation in the Earth–ionosphere waveguide (EIWG) provides a sensitive diagnostic tool of lower-ionospheric perturbations associated with various geophysical processes. In this study, we investigate possible seismo-ionospheric signatures related to the 7 October 2021 Tokyo-area earthquake (EQ) (Mw ≈ 5.9) using sub-ionospheric VLF observations along the NWC (19.8 kHz, Australia) transmitter to Chofu (Japan) propagation path. The analysis focuses on variations in signal amplitude during the evening terminator period, where ionospheric transitions are most pronounced. A significant shift in the sunset terminator time is observed during pre- and post-seismic time. The recorded VLF data are simulated using Long Wavelength Propagation Capability (LWPC) using the well-known Wait’s two-component exponential electron density model with effective reflection height (h′ ) and sharpness factor (β ). Significant pre-seismic anomalies were identified on 05 October 2021, characterized by a lowering of h′ (~3 km) and an increase in β (~0.11 km⁻¹), accompanied by enhanced fluctuations and broadening of the sunset terminator signature. Post-seismic perturbations on 08 October 2021 exhibited similar shifts with a slightly weaker trend. The inferred electron density profiles reveal enhanced ionization at lower altitudes and steeper gradients during disturbed periods compared to quiet conditions. These results suggest that the D/E-region ionosphere underwent measurable modifications prior to and also after the EQ, consistent with lithosphere–atmosphere–ionosphere coupling (LAIC) mechanisms.

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