The ULF magnetic fields generated by thunderstorms: A source of ULF geomagnetic pulsations?

Fraser–Smith, A. C.; Kjono, S. N.

doi:10.1002/2014rs005566

Cited by 10 publications

(3 citation statements)

References 31 publications

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“…Magnetic pulses with duration ∼0.1 s and amplitudes ∼30–40 pT associated with positive electric discharges were recorded at distances over 2·10 3 km (Bösinger et al, ). Fraser‐Smith and Kjono () even suggested that ∼2·10 3 at any time worldwide electric storms can stimulate Pc1 hydromagnetic emissions in the ionosphere and the magnetosphere and thus may control the electromagnetic ULF background noise in the near‐Earth space.…”

Section: Introductionmentioning

confidence: 99%

ULF Electromagnetic Field in the Upper Ionosphere Excited by Lightning

et al. 2018

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We examine excitation of ultralow frequency (ULF) electromagnetic waves by an atmospheric lightning stroke in the upper ionosphere and the role of the ionospheric Alfvén resonator (IAR) in this process. We have theoretically calculated with the developed numerical model the spatial and spectral structures of electromagnetic disturbance in the ULF frequency range 0.1–6.0 Hz excited by an atmospheric lightning stroke on the ground and at ionospheric altitudes. The frequency band under consideration comprises typical frequencies of the IAR and the ionospheric waveguide. The spectra of horizontal magnetic and electric components reveal a spectral multiband structure in the upper ionosphere. The form of spectra depends significantly on the horizontal distance ρ from the source: spectral peaks associated with the IAR are evident at ρ≤400 km, whereas at ρ≥1,000 km the spectral peaks (>4 Hz) corresponding to the ionospheric waveguide modes can be seen. The model predicts that a vertical electric discharge with the charge moment MQ=106 C·m produces at altitude 500 km and ρ = 40 km a pulse with electric and magnetic amplitudes of about 4 mV/m and 4 nT, correspondingly, and duration ∼0.2 s. The pulse amplitude decays rather slowly with distance ∝ρ−1. Detection of ULF response in the upper ionosphere to isolated intense lightning stroke by low‐orbiting satellites with magnetic or electric sensors onboard is quite feasible.

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Section: Introductionmentioning

confidence: 99%

ULF Electromagnetic Field in the Upper Ionosphere Excited by Lightning

et al. 2018

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“…Those from above come mainly from the magnetosphere and are referred to as magnetospheric ULF waves in this paper. Those from below could be the result of lightning occurring in the atmosphere (Fraser-Smith, 1993;Fraser-Smith & Kjono, 2014;Mazur et al, 2018). Waves excited by either internal sources or external sources in the lower atmosphere are referred to as nonmagnetospheric ULF waves.…”

Section: Introductionmentioning

confidence: 99%

Features of Nightside ULF Wave Activity in the Ionosphere

et al. 2019

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We investigate the features of nightside ultralow frequency (ULF) waves in the ionosphere using electric field data in the DC/ULF range observed by the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite over a~5.5-year period from May 2005 to November 2010. The ULF wave events are recognized by an automatic detection algorithm, and a superposed epoch analysis is performed to study the characteristics of ULF waves during geomagnetic storms. The results show that (1) ULF waves of both nonmagnetospheric and magnetospheric origins occur in the ionosphere; (2) nonmagnetospheric ULF waves present seasonal variations but have no clear response to storms; (3) magnetospheric ULF waves show clear association with the recovery phase of storms but have no obvious seasonal variations; and (4) an interhemispheric asymmetry with higher magnetospheric ULF wave occurrence rate in the Southern Hemisphere particularly around storms can be partly explained by the fact that more of selected isolated storms occurred during summer in the Northern Hemisphere (NH), hence higher conductivity in the NH. However, an analysis of few storms during equinoxes also shows a minor asymmetry. These results still indicate that the ionospheric conductivity in the Southern Hemisphere would be lower than in the NH at nighttime. Plain Language SummaryPast knowledge of ultralow frequency (ULF) waves are mainly based on single-point or multipoint observations from high-altitude satellites or ground-based magnetometers. Satellites at low altitudes offer the capability of a global survey of ULF waves that help us to deeply understand ULF waves in the ionosphere. The origins of ULF fluctuations observed by low-altitude satellites are still controversial to date. In this work we statistically explore the characteristics of ULF waves in the ionosphere originated from different sources (e.g., magnetosphere, ionosphere, and atmosphere). Higher occurrence rate of ULF waves from the magnetosphere is in the Southern Hemisphere, indicating lower conductivity there allowing waves more easily propagating into the ionosphere. We also find that ULF waves from different sources have different behaviors with respect to seasonal variations and the response to the strong external perturbations. This study will promote our understanding of ULF waves and their effects on dynamics of the ionosphere.

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“…Some recent stations concerning SR measurements are reported in Zhou et al [2013], Kulak et al [2014], and Sierra et al [2014]. From a more general point of view, not only concerning measurement stations, the interest in the study of the global and local ionosphere electromagnetic properties and applications becomes evident from the number and diversity of recent papers concerning these topics [Cushley and Noël, 2014;Gulyaeva et al, 2014;Cherniak et al, 2014;Nickolaenko and Hayakawa, 2014;Ohta et al, 2013;Fraser-Smith and Kjono, 2014].…”

Section: Introductionmentioning

confidence: 99%

Extremely low frequency band station for natural electromagnetic noise measurement

et al. 2015

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A new permanent ELF measurement station has been deployed in Sierra Nevada, Spain. It is composed of two magnetometers, oriented NS and EW, respectively. At 10 Hz, their sensitivity is 19 μV/pT and the signal-to-noise ratio (SNR) is 28 dB for a time-varying signal of 1 pT, the expected field amplitude in Sierra Nevada. The station operates for frequencies below 24 Hz. The magnetometers, together with their corresponding electronics, have been specifically designed to achieve such an SNR for small signals. They are based on high-resolution search coils with ferromagnetic core and 10 6 turns, operating in limited geometry configuration. Different system noise sources are considered, and a study of the SNR is also included. Finally, some initial Schumann resonance measurements are presented in order to validate the performance of the measurement station, including 1 h length spectra, daily variations of resonance amplitudes and frequencies for the different seasons, and a 3 day spectrogram.

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The ULF magnetic fields generated by thunderstorms: A source of ULF geomagnetic pulsations?

Cited by 10 publications

References 31 publications

ULF Electromagnetic Field in the Upper Ionosphere Excited by Lightning

ULF Electromagnetic Field in the Upper Ionosphere Excited by Lightning

Features of Nightside ULF Wave Activity in the Ionosphere

Extremely low frequency band station for natural electromagnetic noise measurement

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