Strong meteorological disturbances in the atmosphere, accompanied by the generation of waves and turbulence, can affect ionospheric plasma and geomagnetic field. To search for these effects, we have analyzed electromagnetic measurement data from low-orbit Swarm satellites during flights over the typhoon Vongfong 2014. We have found that there are “magnetic ripples” in the upper ionosphere that are transverse to the main geomagnetic field fluctuations of small amplitude (0.5–1.5 nT) with a predominant period of about 10 s caused by small-scale longitudinal currents. Presumably, these quasiperiodic fluctuations are produced by the satellite’s passage through the quasiperiodic ionospheric structure with a characteristic scale of ~70 km induced by the interaction of acoustic waves excited by the typhoon with the E-layer of the ionosphere. In one of the flights over the typhoon, a burst of high-frequency noise (~0.3 Hz) was observed, which can be associated with the excitation of the ionospheric Alfven resonator by atmospheric turbulence.
Abstract. We examine the Pc5 wave power latitudinal distribution in the morning sector along the conjugate magnetometer arrays in Greenland and Antarctica. These distributions are compared with the location of the auroral oval, reconstructed using the OVATION-prime model. This model makes it possible to reconstruct separately the spatial structures of diffuse and monoenergetic precipitation of auroral electrons. Mapping of the spectral power of narrowband Pc5 waves onto the auroral oval has shown that the wave power in the morning sector is localized inside the auroral oval, namely at the poleward edge of diffuse precipitation, but near the peak of monoenergetic precipitation. The case analysis results have been confirmed by a larger statistical study. This observational result confirms the effects earlier found in case studies: the spatial/temporal variations of Pc5 wave power are closely related to the location of the auroral electrojet and magnetospheric field-aligned currents. From the observed relationship between the wave power and the auroral boundaries, it may be concluded that the poleward edge of the diffuse precipitation, around the maximum of the monoenergetic precipitation, is preferred latitude of magnetospheric field-line resonance excitation. This effect is not taken into account by modern theories of ULF Pc5 waves.
The eruption of the Tonga volcano on January 13 and 15, 2022 and related intense lightning activity led to the excitation of a number of specific electromagnetic oscillations in different frequency ranges. We examine properties of these oscillations, using data from magnetometers of various types located in Kamchatka and in the Pacific region. We confirmed that there might have been a geomagnetic response to the formation of an acoustic resonance between the Earth surface and the ionosphere: localized harmonic oscillations with a frequency 3.5–4.0 mHz, which lasted for ~1.5 hr, were detected ~15 min after the beginning of the eruption at distance of ~800 km. An increase was observed in the intensity of the Schumann resonance at stations in the Far East. Broadband emission stimulated by intense volcanic lightning was detected to occur in the Pc1 range (2–5 Hz). The emission presumably results from the excitation of the magnetosonic waveguide in the upper ionosphere by lightning activity.
We have examined snapshots of overlaid ultra-violet (UV) auroral images from POLAR and IMAGE spacecraft and ULF wave power in the Pi2 frequency band (5-30 mHz). The latitudinal distribution of the Pi2 spectral power, as well as the position of the ionospheric electrojet, are inferred from the MACCS-CARISMA-MEASURE array of magnetic stations. A substorm develops as a series of "detonations", accompanied by an enhancement of auroral luminosity, intensification of the ionospheric currents, and a burst of Pi2 wave power. The epicenter of each detonation leaps during each activation poleward and westward. The latitudinal location of the auroral ionospheric westward electrojet and Pi2 power is found to be mainly associated with the poleward border of the auroral activation region. The result of case studies is supported by statistical superposed latitudinal distributions of the auroral intensity and Pi2 power. The found correspondence between the UV auroral oval and Pi2 power "epicenter" may help to identify a possible channel of Pi2 wave energy transmission from the magnetotail to the ground. KEYWORDS: ULF waves; Pi2 pulsations; substorm; auroral oval; ionospheric electrojet.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.