Earth's Electron Research Articles

Influence of solar radiation on ionosphere over India

The ionosphere is a region of the upper atmosphere where free electrons and ions are created by solar radiation. An effort is made to study the solar radiation influence on the earth's ionosphere's total electron content (TEC) across the low latitude Indian subcontinent from January to October 2022. TEC readings were obtained using GNSS receivers over Bengaluru (13.021 °N, 77.570 °E) and Hyderabad (17.417 °N, 78.551 °E). Ionospheric TEC variations are studied by measuring the degree to which satellite-sent GPS signals are disrupted. The results were compared with geomagnetic measurements such as disturbed storm time (Dst) index and planetary K-index (Kp) and analyzed with TEC anomalies during geomagnetic storms, and the results may be used to estimate the magnetic field of the Earth. The study revealed that ionospheric storms had an advantageous impact in January, March, and April of 2022, but a negative effect in July 2022.

The location of the chemical bond. Application of long covalent bond theory to the structure of silica.

Oxygen is the most abundant terrestrial element and is found in a variety of materials, but still wanting is a universal theory for the stability and structural organization it confers. Herein, a computational molecular orbital analysis elucidates the structure, stability, and cooperative bonding of α-quartz silica (SiO2). Despite geminal oxygen-oxygen distances of 2.61-2.64Å, silica model complexes exhibit anomalously large O-O bond orders (Mulliken, Wiberg, Mayer) that increase with increasing cluster size-as the silicon-oxygen bond orders decrease. The average O-O bond order in bulk silica computes to 0.47 while that for Si-O computes to 0.64. Thereby, for each silicate tetrahedron, the six O-O bonds employ 52% (5.61 electrons) of the valence electrons, while the four Si-O bonds employ 48% (5.12 electrons), rendering the O-O bond the most abundant bond in the Earth's crust. The isodesmic deconstruction of silica clusters reveals cooperative O-O bonding with an O-O bond dissociation energy of 4.4kcal/mol. These unorthodox, long covalent bonds are rationalized by an excess of O 2p-O 2p bonding versus anti-bonding interactions within the valence molecular orbitals of the SiO4 unit (48 vs. 24) and the Si6O6 ring (90 vs. 18). Within quartz silica, oxygen 2p orbitals contort and organize to avoid molecular orbital nodes, inducing the chirality of silica and resulting in Möbius aromatic Si6O6 rings, the most prevalent form of aromaticity on Earth. This long covalent bond theory (LCBT) relocates one-third of Earth's valence electrons and indicates that non-canonical O-O bonds play a subtle, but crucial role in the structure and stability of Earth's most abundant material.

A Rapid Localized Deceleration of Earth's Radiation Belt Relativistic Electrons Driven by Storm Proton Injection

AbstractEarth's radiation belt relativistic electron dropouts frequently occur during the main phase of geomagnetic storms, which have been partially attributed to the ring current ion enhancements causing geomagnetic field reconfigurations. In contrast to early studies on the global radiation belt response to the ring current buildup on a timescale of several hours, we here describe a rapid, localized, significant decay of relativistic electrons driven by freshly injected energetic protons during the 27 May 2017 geomagnetic storm. Near the proton injection front, the magnetic field lines were stretched outward, with an inferred migration of their equatorial crossings by ∼0.5 RE during several minutes. Because of the betatron and Fermi decelerations, the relativistic electron fluxes decreased by 2–3 orders of magnitude with pitch‐angle distributions evolving from pancake/flat‐top type to cigar type. This rapid localized response pattern of relativistic electrons could be general over strong particle injections during both geomagnetic storms and substorms.

Zebra Stripe Patterns in Energetic Ion Spectra at Saturn

AbstractMagnetospheric convective electric fields that could radially transport particles adiabatically, may leave their imprints in the form of energy‐time dispersed patterns termed ”zebra stripes”. Inspired by comprehensive studies on zebra stripes in Earth's electron radiation belts, similar electron signatures were found and explained in Saturn's inner magnetosphere. Using Cassini Magnetosphere Imaging Instrument observations, we demonstrate that the zebra‐stripes in proton and water group ion spectrograms at the energy range from 30 keV to ∼1 MeV, which coexist with electron zebra‐stripes, can be traced to the same electric field, even though the associated radial flows were originally thought to be too slow to disturb the fast azimuthal energetic ion drift. The simultaneous observations of zebra stripes in electrons and ions further establish the importance of the planet's noon‐midnight electric field as a regulator of radiation belt dynamics.

Energy-dependent Boundaries of Earth's Radiation Belt Electron Slot Region

Abstract The variations in radiation belt boundaries reflect competition between acceleration and loss physical processes of energetic electrons, which is an important issue for radiation belts of planets with an internal magnetic field (e.g., Earth, Jupiter, and Saturn). Based on high-quality measurements from Van Allen Probes spanning the years 2014–2018, we develop an empirical model of the energy-dependent boundaries of Earth's electron radiation belt slot region, showing that the lower boundary follows a logarithmic function of the electron energy while the upper boundary is controlled by two competing energy-dependent processes, namely compression and recovery. The compression process relates linearly to a 15 hr averaged Kp index, while the recovery process is found to be approximately proportional to time. Detailed data-model comparisons demonstrate that our model, using only the Kp index and time epoch as inputs, reconstructs the slot region boundaries in real time for 200 keV to 2 MeV electrons under varying geomagnetic conditions. Such a data-driven empirical model is prerequisite to understanding the dynamic changes of the slot region in response to both solar and geomagnetic activities. The model can be readily incorporated into future global simulations of radiation belt electron dynamics in Earth's inner magnetosphere and provide new insights into the study of Saturn's and Jupiter's radiation belt variability.

Statistical Distribution of Bifurcation of Earth's Inner Energetic Electron Belt at Tens of keV

AbstractWe present a survey of the bifurcation of the Earth's energetic electron belt (tens of keV) using 6‐year measurements from Van Allen Probes. The inner energetic electron belt usually presents one‐peak radial structure with high flux intensity at L < ∼2.5, which however can be bifurcated to exhibit a double‐peak radial structure. By automatically identifying the events of bifurcation based on Radiation Belt Storm Probes Ion Composition Experiment data, we find that the bifurcation is mostly observed at ∼30–100 keV with a local flux minimum at L = ∼2.0 to ∼2.3 under relatively quiet geomagnetic conditions, typically after a significant flux enhancement due to radial diffusion or injections to L < ∼2.5. The bifurcation typically lasts for a few days during quiet periods until interrupted by injections or radial diffusion. The L‐shell, energy, and seasonal dependences of the occurrence of bifurcated inner electron belt support the important role of electron scattering by very low‐frequency transmitter waves in the bifurcation formation.

Earth's ionosphere D-region vertical electron density profile data during March 1-31, 2017 according to high-latitudinal Tumanny observatory partial reflection radar measurements and Polar Geophysical Institute's model.

The Earth's high-latitudinal D-Region ionosphere measurements are rarely performed continuously and with high temporal resolution. This data article provides the observed and modelled data on D-Region electron density variations during March 1-31, 2017 with 1-minute resolution. Both datasets share the same data-files’ structure and naming conventions. D-Region electron density observations were performed with the ground-based vertical sounding medium frequency (MF) partial reflection radar located at Tumanny observatory (69.0°N, 35.7°E). Modelling of D-Region ionosphere electron density variations were performed for the same period using Polar Geophysical Institute's theoretical model of quiet-time D-Region ionosphere. These datasets are valuable (a) to validate and cross-compare existing models of the D-Region ionosphere, (b) to verify and improve HF-band radio-waves propagation models, and (c) in investigations of the Earth's-ionosphere waveguide properties in dependence on the features of the lower part of the waveguide, i.e., the D-Region (often referenced to as the D-Layer). Both datasets are required to gain the reproducibility of results reported by Gomonov and co-authors [2019, doi: 10.1051/epjconf/201922403011].

Empirically Estimated Electron Lifetimes in the Earth's Radiation Belts: Comparison With Theory.

We compute quasilinear diffusion rates due to pitch angle scattering by various mechanisms in the Earth's electron radiation belts. The calculated theoretical lifetimes are compared with observed decay rates, and we find excellent qualitative agreement between the two. The overall structure of the observed lifetime profiles as a function of energy and L is largely due to plasmaspheric hiss and Coulomb scattering. The results also reveal a local minimum in lifetimes in the inner zone at lower energy ( ∼50 keV), attributed to enhanced scattering via ground‐based very low frequency transmitters, and a reduction in lifetimes at higher L and energy ( >1 MeV), attributed to enhanced electromagnetic ion cyclotron wave scattering. In addition, we find significant quantitative disagreement at L<3.5, where the theoretical lifetimes are typically a factor of ∼10 larger than the observed, pointing to an additional loss process that is missing from current models. We discuss potential factors that could contribute to this disagreement.

Pedersen Ionic Contribution in Different Time Scales

AbstractPedersen conductivity is one of the main parameters in atmospheric electrodynamics, magnetosphere‐ionosphere‐thermosphere coupling, and several other geophysical processes. It is determined by the collision frequency between charged and neutral components and the Earth's magnetic field intensity through the gyrofrequency. This work analyzes the contribution of different ionic species to the variability of Pedersen conductance in time scales from hours to years within the period 1964–2008 based on the results of various atmospheric and ionospheric models. The main results are (1) there is a positive correlation between O+ density and Pedersen conductance, (2) Pedersen conductance of F layer has a larger increase with the solar activity than that of E layer, (3) Pedersen conductance has a long‐term trend that is determined by Earth's magnetic field intensity and electron density, and (4) at midlatitudes trends are mainly governed by the Earth's magnetic field and modulated by the electron density, while at high latitudes both are important.

The Response of Earth's Electron Radiation Belts to Geomagnetic Storms: Statistics From the Van Allen Probes Era Including Effects From Different Storm Drivers

AbstractA statistical study was conducted of Earth's radiation belt electron response to geomagnetic storms using NASA's Van Allen Probes mission. Data for electrons with energies ranging from 30 keV to 6.3 MeV were included and examined as a function of L‐shell, energy, and epoch time during 110 storms with SYM‐H ≤−50 nT during September 2012 to September 2017 (inclusive). The radiation belt response revealed clear energy and L‐shell dependencies, with tens of keV electrons enhanced at all L‐shells (2.5 ≤ L ≤ 6) in all storms during the storm commencement and main phase and then quickly decaying away during the early recovery phase, low hundreds of keV electrons enhanced at lower L‐shells (~3 ≤ L ≤ ~4) in upward of 90% of all storms and then decaying gradually during the recovery phase, and relativistic electrons throughout the outer belt showing main phase dropouts with subsequent and generally unpredictable levels of replenishment during the recovery phase. Compared to prestorm levels, electrons with energies &gt;1 MeV also revealed a marked increase in likelihood of a depletion at all L‐shells through the outer belt (3.5 ≤ L ≤ 6). Additional statistics were compiled revealing the storm time morphology of the radiation belts, confirming the aforementioned qualitative behavior. Considering storm drivers in the solar wind: storms driven by coronal mass ejection (CME) shocks/sheaths and CME ejecta only are most likely to result in a depletion of &gt;1‐MeV electrons throughout the outer belt, while storms driven by full CMEs and stream interaction regions are most likely to produce an enhancement of MeV electrons at lower (L &lt; ~5) and higher (L &gt; ~4.5) L‐shells, respectively. CME sheaths intriguingly result in a distinct enhancement of ~1‐MeV electrons around L~5.5, and on average, CME sheaths and stream interaction regions result in double outer belt structures.

Observations and Fokker‐Planck Simulations of the L‐Shell, Energy, and Pitch Angle Structure of Earth's Electron Radiation Belts During Quiet Times

AbstractThe evolution of the radiation belts in L‐shell (L), energy (E), and equatorial pitch angle (α 0) is analyzed during the calm 11‐day interval (4–15 March) following the 1 March 2013 storm. Magnetic Electron and Ion Spectrometer (MagEIS) observations from Van Allen Probes are interpreted alongside 1D and 3D Fokker‐Planck simulations combined with consistent event‐driven scattering modeling from whistler mode hiss waves. Three (L, E, α 0) regions persist through 11 days of hiss wave scattering; the pitch angle‐dependent inner belt core (L ~ &lt;2.2 and E &lt; 700 keV), pitch angle homogeneous outer belt low‐energy core (L &gt; ~5 and E~ &lt; 100 keV), and a distinct pocket of electrons (L ~ [4.5, 5.5] and E ~ [0.7, 2] MeV). The pitch angle homogeneous outer belt is explained by the diffusion coefficients that are roughly constant for α 0 ~ &lt;60°, E &gt; 100 keV, 3.5 &lt; L &lt; L pp ~ 6. Thus, observed unidirectional flux decays can be used to estimate local pitch angle diffusion rates in that region. Top‐hat distributions are computed and observed at L ~ 3–3.5 and E = 100–300 keV.

The Contribution of Compressional Magnetic Pumping to the Energization of the Earth's Outer Electron Radiation Belt During High‐Speed Stream‐Driven Storms

AbstractCompressional magnetic pumping is an interaction between cyclic magnetic compressions and pitch angle scattering with the scattering acting as a catalyst to allow the cyclic compressions to energize particles. Compressional magnetic pumping of the outer electron radiation belt at geosynchronous orbit in the dayside magnetosphere is analyzed by means of computer simulations, wherein solar wind compressions of the dayside magnetosphere energize electrons with electron pitch angle scattering by chorus waves and by electromagnetic ion cyclotron (EMIC) waves. The magnetic pumping is found to produce a weak bulk heating of the electron radiation belt, and it also produces an energetic tail on the electron energy distribution. The amount of energization depends on the robustness of the solar wind compressions and on the amplitude of the chorus and/or EMIC waves. Chorus‐catalyzed pumping is better at energizing medium‐energy (50–200 keV) electrons than it is at energizing higher‐energy electrons; at high energies (500 keV–2 MeV) EMIC‐catalyzed pumping is a stronger energizer. The magnetic pumping simulation results are compared with energy diffusion calculations for chorus waves in the dayside magnetosphere; in general, compressional magnetic pumping is found to be weaker at accelerating electrons than is chorus‐driven energy diffusion. In circumstances when solar wind compressions are robust and when EMIC waves are present in the dayside magnetosphere without the presence of chorus, EMIC‐catalyzed magnetic pumping could be the dominant energization mechanism in the dayside magnetosphere, but at such times loss cone losses will be strong.

A New Spin on Neural Processing: Quantum Cognition.

Although quantum mechanics is fundamental for understanding molecular mechanisms in physics and chemistry, it has usually been assumed to be unimportant for understanding molecular mechanisms of biological systems. However, there is increasing evidence that quantum mechanics is important for understanding some biological phenomena (Lambert et al., 2013), such as energy transfer in photosynthesis (Fassioli et al., 2014), navigation by birds using the earth's magnetic field (Hiscock et al., 2016), and electron and hydrogen tunneling in biochemical reactions (Klinman and Kohen, 2013). There have also been proposals that quantum mechanics may help explain aspects of brain function.

Reproducing the observed energy‐dependent structure of Earth's electron radiation belts during storm recovery with an event‐specific diffusion model

AbstractWe present dynamic simulations of energy‐dependent losses in the radiation belt “slot region” and the formation of the two‐belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data‐driven spatially and temporally resolved whistler‐mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2–6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy‐dependent outer boundary to the inner zone that extends to higher L shells at lower energies and (c) an “S‐shaped” energy‐dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy‐dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15 days, although the “S shape” can also be reproduced by assuming equilibrium conditions. The highest‐energy electrons (E &gt; 300 keV) of the inner region of the outer belt (L ~ 4–5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data‐driven and event‐specific conditions.

Electron acceleration associated with the magnetic flux pileup regions in the near‐Earth plasma sheet: A multicase study

AbstractUsing the Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations, we study electron acceleration (&lt;30 keV) in the magnetic flux pileup regions (FPRs) in the near‐Earth plasma sheet (X ~ –10 RE). We present three cases of FRPs associated with dipolarization fronts and substorm dipolarization. Based on the characteristics of the magnetic field, we defined the magnetic field enhancement region (MFER) as the magnetic field with significant ramp that is usually observed near the dipolarization front boundary layer. On the other side, the increased magnetic field without a significant ramp is the rest of a FPR. Our results show that betatron acceleration dominates for 10–30 keV electrons inside the MFER, whereas Fermi acceleration dominates for 10–30 keV electrons inside the rest of the FPR. Betatron acceleration is caused by the enhancement of the local magnetic field, whereas Fermi acceleration is related to the shrinking length of magnetic field line. These accelerated electrons inside the FPRs in the near‐Earth tail play a potentially important role in the evolution of the Earth's electron radiation belt and substorms.

On the cause and extent of outer radiation belt losses during the 30 September 2012 dropout event

AbstractOn 30 September 2012, a flux “dropout” occurred throughout Earth's outer electron radiation belt during the main phase of a strong geomagnetic storm. Using eight spacecraft from NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Van Allen Probes missions and NOAA's Geostationary Operational Environmental Satellites constellation, we examined the full extent and timescales of the dropout based on particle energy, equatorial pitch angle, radial distance, and species. We calculated phase space densities of relativistic electrons, in adiabatic invariant coordinates, which revealed that loss processes during the dropout were &gt; 90% effective throughout the majority of the outer belt and the plasmapause played a key role in limiting the spatial extent of the dropout. THEMIS and the Van Allen Probes observed telltale signatures of loss due to magnetopause shadowing and subsequent outward radial transport, including similar loss of energetic ring current ions. However, Van Allen Probes observations suggest that another loss process played a role for multi‐MeV electrons at lower L shells (L* &lt; ~4).

Rebuilding of the Earth's outer electron belt during 8–10 October 2012

Geomagnetic storms often include strong magnetospheric convection caused by sustained periods of southward interplanetary magnetic field. During periods of strong convection, the Alfvén layer, which separates the region of sunward convection from closed drift shells, is displaced earthward allowing plasma sheet particles with energies in the hundreds of keV direct access inside of geosynchronous. Subsequent outward motion of the Alfvén boundary and adiabatic energization during storm recovery traps plasma sheet electrons on closed drift shells providing a seed population for the outer radiation belts. In situ observations of the 8–10 October 2012 geomagnetic storm and MHD test particle simulations illustrate the morphology of this process. Data and modeling results support the conclusion that recovery of ~ 1 MeV electrons at geosynchronous is mainly due to global convection and dipolarization associated injections from the plasma sheet.

Space weather impacts on satellites and forecasting the Earth's electron radiation belts with SPACECAST

Satellites can be damaged by high energy charged particles in the Earth's radiation belts and during solar energetic particle (SEP) events. Here we review the growing reliance on satellite services, new vulnerabilities to space weather, and previous events that have led to loss of service. We describe a new European system to forecast the radiation belts up to 3 h ahead, which has three unique features: first, it uses physics‐based models, which include wave‐particle interactions; second, it provides a forecast for the whole outer radiation belt including geostationary, medium, and slot region orbits; third, it is a truly international effort including Europe, United States, and Japan. During the 8–9 March 2012 storm and SEP event, the models were able to forecast the &gt;800 keV electron flux to within a factor of 2 initially, and later to within a factor of 10 of the GOES data. Although ACE and GOES data became unreliable during the SEP event, the system continued forecasting without interruption using ground‐based magnetometers. A forecast of the 24 h electron fluence &gt;2 MeV is used to provide a risk index for satellite operators. We show that including wave‐particle interactions for L* &gt; 6.5 improves the agreement with GOES data substantially and that a fast inward motion of the magnetopause to L* &lt; 8 is related to rapid loss of relativistic electrons at geostationary orbit. Thus, we suggest that better wave‐particle models and better coupling between the solar wind and the models of the magnetopause and radiation belts should lead to better forecasting.

The spectral extent of chorus in the off‐equatorial magnetosphere

Magnetospheric chorus waves are a major driver of acceleration and loss in the Earth's outer electron radiation belt. The spectral extent of chorus is a key parameter in quantifying the global effect of chorus on energetic particle populations by determining the range of resonant electron energies. However, statistics of spectral properties are sparse, particularly in the off‐equatorial magnetosphere. We use a database of chorus observations from the Polar spacecraft to generate statistics on the normalized chorus frequency (with the respect to the minimum field line gyrofrequency, Ωmin) as a function of magnetic local time (MLT) (0 &lt; MLT &lt; 24), L‐shell (3 &lt; L &lt; 11), and magnetic latitude (|λ|&lt; 65°). We find that, on average, the chorus spectrum peaks in the range of 0.1–0.4 Ωmin, varying significantly with λ, R0 and MLT. The normalized chorus peak frequency is found to decrease with increasing R0, and decreases with increasing latitude below ∼ 25°. When fit to a Gaussian spectral model, lower band chorus is found to have a bandwidth &lt; 0.1 Ωmin, which is narrower than assumed in most diffusion models. Diffusion coefficients calculated using the University of California at Los Angeles (UCLA) Full Diffusion Code show that wave‐particle interactions on the nightside are highly sensitive to both the peak frequency and bandwidth of chorus, yet on the dayside scattering is mostly sensitive to the peak frequency as a result of the wider latitudinal extent of the waves. We also find that fitting a Gaussian to the logarithm of the spectrum reduces fit errors by over 60%, indicating that inclusion of arbitrary spectral forms may improve the accuracy of wave models within radiation belt simulations.

Earthing: Health Implications of Reconnecting the Human Body to the Earth's Surface Electrons

Environmental medicine generally addresses environmental factors with a negative impact on human health. However, emerging scientific research has revealed a surprisingly positive and overlooked environmental factor on health: direct physical contact with the vast supply of electrons on the surface of the Earth. Modern lifestyle separates humans from such contact. The research suggests that this disconnect may be a major contributor to physiological dysfunction and unwellness. Reconnection with the Earth's electrons has been found to promote intriguing physiological changes and subjective reports of well-being. Earthing (or grounding) refers to the discovery of benefits—including better sleep and reduced pain—from walking barefoot outside or sitting, working, or sleeping indoors connected to conductive systems that transfer the Earth's electrons from the ground into the body. This paper reviews the earthing research and the potential of earthing as a simple and easily accessed global modality of significant clinical importance.