scholarly journals Thermospheric Neutral Winds as the Cause of Drift Shell Distortion in Earth’s Inner Radiation Belt

2021 ◽  
Vol 8 ◽  
Author(s):  
Solène Lejosne ◽  
Mariangel Fedrizzi ◽  
Naomi Maruyama ◽  
Richard S. Selesnick
Keyword(s):  
Electric Field ◽  
Local Time ◽  
Large Scale ◽  
Radiation Belt ◽  
Energetic Electron ◽  
Recent Analysis ◽  
Quiet Time ◽  
Time Asymmetry ◽  
Electron Intensity

Recent analysis of energetic electron measurements from the Magnetic Electron Ion Spectrometer instruments onboard the Van Allen Probes showed a local time variation of the equatorial electron intensity in the Earth’s inner radiation belt. The local time asymmetry was interpreted as evidence of drift shell distortion by a large-scale electric field. It was also demonstrated that the inclusion of a simple dawn-to-dusk electric field model improved the agreement between observations and theoretical expectations. Yet, exactly what drives this electric field was left unexplained. We combine in-situ field and particle observations, together with a physics-based coupled model, the Rice Convection Model (RCM) Coupled Thermosphere-Ionosphere-Plasmasphere-electrodynamics (CTIPe), to revisit the local time asymmetry of the equatorial electron intensity observed in the innermost radiation belt. The study is based on the dawn-dusk difference in equatorial electron intensity measured at L = 1.30 during the first 60 days of the year 2014. Analysis of measured equatorial electron intensity in the 150–400 keV energy range, in-situ DC electric field measurements and wind dynamo modeling outputs provide consistent estimates of the order of 6–8 kV for the average dawn-to-dusk electric potential variation. This suggests that the dynamo electric fields produced by tidal motion of upper atmospheric winds flowing across Earth’s magnetic field lines - the quiet time ionospheric wind dynamo - are the main drivers of the drift shell distortion in the Earth’s inner radiation belt.

scholarly journals Electron radiation belt dynamics during magnetic storms and in quiet time

2018 ◽  
Vol 4 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Леонид Лазутин ◽  
Leonid Lazutin ◽  
Алексей Дмитриев ◽  
Aleksey Dmitriev ◽  
Алла Суворова ◽  
...  
Keyword(s):  
Electric Field ◽  
Magnetic Storm ◽  
Large Scale ◽  
Radiation Belt ◽  
Electron Flux ◽  
Continuous Series ◽  
Outer Electron ◽  
Quiet Time ◽  
Trapping Region ◽  
Individual Character

The paper discusses the dynamics of the outer electron belt, adiabatic and nonadiabatic mechanisms of replenishment and losses of energetic electrons. Under undisturbed conditions, the outer electron belt gradually empties: in the inner magnetosphere due to electron precipitation in the atmosphere and in the quasi-trapping region due to losses at the magnetopause because drift shells of electrons are not closed there. The latter process does not occur in normal years due to the masking replenishment by freshly accelerated particles, but in years of extremely low activity it leads to a significant decrease in the electron population of the belt. During the magnetic storm main phase, the first reason for the decrease in the electron flux intensity is the adiabatic cooling associated with conservation of adiabatic invariants and complemented by precipitation of electrons into the atmosphere and their dropout at the magnetopause. Electron flux increases involve EB electron injection by the induction electric field of substorm activation and by the large-scale solar wind electric field, with pitch energy diffusion along with adiabatic heating in the recovery phase. The rate of electron flux recovery after a storm is determined by the ratio of nonadiabatic increases and losses; hence the electron flux represents a continuous series from low to very high values. The combination of these processes determines the individual character of radiation belt development during each magnetic storm and the behavior of the belt in the quiet time.

scholarly journals Electron radiation belt dynamics during magnetic storms and in quiet time

2018 ◽  
Vol 4 (1) ◽  
pp. 59-71
Author(s):  
Леонид Лазутин ◽  
Leonid Lazutin ◽  
Алексей Дмитриев ◽  
Aleksey Dmitriev ◽  
Алла Суворова ◽  
...  
Keyword(s):  
Electric Field ◽  
Magnetic Storm ◽  
Large Scale ◽  
Radiation Belt ◽  
Electron Flux ◽  
Continuous Series ◽  
Outer Electron ◽  
Quiet Time ◽  
Trapping Region ◽  
Individual Character

The paper discusses the dynamics of the outer electron belt, adiabatic and nonadiabatic mechanisms of replenishment and losses of energetic electrons. Under undisturbed conditions, the outer electron belt gradually empties: in the inner magnetosphere due to electron precipitation in the atmosphere and in the quasi-trapping region due to losses at the magnetopause because drift shells of electrons are not closed there. The latter process does not occur in normal years due to the masking replenishment by freshly accelerated particles, but in years of extremely low activity it leads to a significant decrease in the electron population of the belt. During the magnetic storm main phase, the first reason for the decrease in the electron flux intensity is the adiabatic cooling associated with conservation of adiabatic invariants and complemented by precipitation of electrons into the atmosphere and their dropout at the magnetopause. Electron flux increases involve EB electron injection by the induction electric field of substorm activation and by the large-scale solar wind electric field, with pitch energy diffusion along with adiabatic heating in the recovery phase. The rate of electron flux recovery after a storm is determined by the ratio of nonadiabatic increases and losses; hence the electron flux represents a continuous series from low to very high values. The combination of these processes determines the individual character of radiation belt development during each magnetic storm and the behavior of the belt in the quiet time.

scholarly journals Comparison of large-scale Birkeland currents determined from Iridium and SuperDARN data

2006 ◽  
Vol 24 (3) ◽  
pp. 941-959 ◽  
Author(s):  
D. L. Green ◽  
C. L. Waters ◽  
B. J. Anderson ◽  
H. Korth ◽  
R. J. Barnes
Keyword(s):  
Electric Field ◽  
Large Scale ◽  
Radar Data ◽  
Space Environment ◽  
Near Earth Space ◽  
Radar Network ◽  
High Latitude Ionosphere ◽  
Ionospheric Electric Field ◽  
Birkeland Currents

Abstract. The Birkeland currents, J||, electrically couple the high latitude ionosphere with the near Earth space environment. Approximating the spatial distribution of the Birkeland currents may be achieved using the divergence of the ionospheric electric field, , assuming zero conductance gradients such that . In this paper, electric field data derived from the Super Dual Auroral Radar Network (SuperDARN) are used to calculate , which is compared with the Birkeland current distribution derived globally from the constellation of Iridium satellites poleward of 60° magnetic latitude. We find that the assumption of zero conductance gradients is often a poor approximation. On the dayside, in regions where the SuperDARN electric field is constrained by radar returns, the agreement in the locations of regions of upward and downward current between and J|| obtained from Iridium data is reasonable with differences of less than 3° in the latitudinal location of major current features. It is also shown that away from noon, currents arising from conductance gradients can be larger than the component. By combining the estimate in regions of radar coverage with in-situ estimates of conductance gradients from DMSP satellite particle data, the agreement with the Iridium derived J|| is considerably improved. However, using an empirical model of ionospheric conductance did not account for the conductance gradient current terms. In regions where radar data are sparse or non-existent and therefore constrained by the statistical potential model the approximation does not agree with J|| calculated from Iridium data.

scholarly journals Magnetic local time dependency of radiation belt electron precipitation: impact on polar ozone

2020 ◽  
Author(s):  
Pekka T. Verronen ◽  
Daniel R. Marsh ◽  
Monika E. Szeląg ◽  
Niilo Kalakoski
Keyword(s):  
Local Time ◽  
Radiation Belt ◽  
Climate Model ◽  
Energetic Electron ◽  
Coupled Model ◽  
Magnetic Local Time ◽  
Polar Regions ◽  
Research Activity ◽  
Diurnal Variability ◽  
Polar Ozone

Abstract. The radiation belts are regions in the near-Earth space where solar wind electrons are captured by the Earth's magnetic field. A portion of these electrons is continuously lost into the atmosphere where they cause ionisation and chemical changes. Driven by solar activity, electron forcing leads to ozone variability in the polar regions. Understanding possible dynamical connections to regional climate is an on-going research activity which supports the assessment of greenhouse gas driven climate change by better definition of the solar-driven variability. In the context of the Coupled Model Intercomparison Project Phase 6 (CMIP6), energetic electron and proton precipitation is included in the solar forcing recommendation for the first time. For radiation belt electrons, CMIP6 forcing is from a daily, zonal mean proxy model. This zonal mean model ignores the well-known dependency of precipitation on magnetic local time (MLT), i.e. its diurnal variability. Here we use the Whole Atmosphere Community Climate Model with lower ionospheric chemistry extension (WACCM-D) to study the effect of MLT dependency of electron forcing on the polar ozone response. We analyse simulations applying MLT-dependent and MLT-independent forcings, and contrast ozone responses in monthly mean data as well as in monthly means of individual local time sectors. We consider two cases: 1) year 2003 and 2) extreme, long-duration forcing. Our results indicate that the ozone responses to MLT-dependent and MLT-independent forcings are very similar, and the differences found are small compared to those related to overall uncertainties in electron forcing. We conclude that electron forcing that ignores the MLT dependency will still provide an accurate ozone response in long-term climate simulations.

scholarly journals Operando Investigation of the Locally Enhanced Electric Field Treatment (LEEFT) Harnessing Lightning-Rod Effect for Rapid Bacteria Inactivation

2021 ◽  
Author(s):  
Ting Wang ◽  
Devin k. Brown ◽  
Xing Xie
Keyword(s):  
Electric Field ◽  
Large Scale ◽  
Side Reactions ◽  
Ros Generation ◽  
Mechanism Study ◽  
Membrane Pore ◽  
Bacteria Inactivation ◽  
Pore Closure ◽  
Electric Field Treatment

Abstract The growth of undesired bacteria causes numerous problems. Here, we show that locally enhanced electric field treatment (LEEFT) can cause rapid bacteria inactivation by electroporation without any side reactions. The bacteria inactivation is studied in situ at the single-cell level on a lab-on-a-chip that has nanowedge-decorated electrodes. Rapid bacteria inactivation occurs specifically at nanowedge tips where the electric field is enhanced due to the lightning-rod effect. The mechanism study shows that the bacteria inactivation is caused by electroporation induced by the locally enhanced electric field. The bacteria inactivation performance depends on the strength of the enhanced electric field instead of the applied voltage, and no ROS generation is detected when >90% bacteria inactivation is achieved. Quick membrane pore closure under moderate LEEFT indicates that electroporation is the predominant mechanism. LEEFT only requires facile treatment to achieve bacteria inactivation, which is safe for treating delicate samples and energy-efficient for large scale applications. The findings in this work can provide strong supports for the future applications of LEEFT.

scholarly journals Outflowing ionospheric oxygen-ion motion in a reconfigurating magnetosphere

1997 ◽  
Vol 15 (1) ◽  
pp. 5-16 ◽  
Author(s):  
E. B. Wodnicka ◽  
M. Banaszkiewicz
Keyword(s):  
Electric Field ◽  
Local Time ◽  
Magnetic Moment ◽  
Vector Potential ◽  
Pitch Angle ◽  
Large Scale ◽  
Initial Energy ◽  
Spatial And Temporal Scales ◽  
Ion Energization ◽  
Perpendicular Component

Abstract. During substorms, large-scale changes of the topology of the Earth's magnetosphere following the variation of the characteristics of the interplanetary medium are accompanied by the induction of the electric field. In this study a model of a time-dependent magnetosphere is constructed and the large-scale features of the induced electric field are described. Local-time sectors with upward or downward field-aligned component and with intense perpendicular component of the electric field are distinguished. The electric-field structure implies the existence of outflow regions particularly effective in ion energization. With the vector potential adopted in the study, the region from which the most energized ions originate is defined by the local-time sector near 2100 MLT and latitude zone near 71° MLAT. The motion of ionospheric oxygen ions of energy 0.3–3 keV is investigated during a 5-min reconfiguration event when the tail-like magnetospheric field relaxes to the dipole-like field. As the characteristics of plasma in the regions near the equatorial plane affect the substorm evolution, the energy, pitch angle, and the magnetic moment of ions in these regions are analyzed. These quantities depend on the initial energy and pitch angle of the ion and on the magnetic and electric field it encounters on its way. With the vector potential adopted, the energy attained in the equatorial regions can reach hundreds of keV. Three regimes of magnetic-moment changes are identified: adiabatic, oscillating, and monotonous, depending on the ion initial energy and pitch angle and on the magnetic- and electric-field spatial and temporal scales. The implications for the global substorm dynamics are discussed

scholarly journals Magnetic storm acceleration of radiation belt electrons observed by the Scintillating Fibre Detector (SFD) onboard EQUATOR-S

1999 ◽  
Vol 17 (12) ◽  
pp. 1622-1625 ◽  
Author(s):  
M. Cyamukungu ◽  
C. Lippens ◽  
L. Adams ◽  
R. Nickson ◽  
C. Boeder ◽  
...  
Keyword(s):  
Magnetic Storm ◽  
Geomagnetic Activity ◽  
Radiation Belt ◽  
Electron Flux ◽  
Energetic Electron ◽  
Energetic Particles ◽  
Radiation Belt Electrons ◽  
Instruments And Techniques ◽  
Storms And Substorms

Abstract. On the basis of the currents induced by electron fluxes in the Scintillating Fibre Detector (SFD) onboard the EQUATOR-S satellite launched on 2 December 1997, an in-situ acceleration of radiation belt electrons is found to possibly contribute to the increase of the flux of electrons with energies greater than 400 keV. The data acquired between 16 December 1997 and 30 April 1998 on the 500–67300 km, 4° inclination EQUATOR-S orbit show that the increase of the energetic electron flux corresponds to the enhanced geomagnetic activity measured through the Dst index.Key words. Magnetospheric physics (energetic particles · trapped; storms and substorms; instruments and techniques)

scholarly journals Statistical study of the substorm onset: its dependence on solar wind parameters and solar illumination

2005 ◽  
Vol 23 (6) ◽  
pp. 2069-2079 ◽  
Author(s):  
H. Wang ◽  
H. Lühr ◽  
S. Y. Ma ◽  
P. Ritter
Keyword(s):  
Solar Wind ◽  
Local Time ◽  
Large Scale ◽  
Statistical Study ◽  
Energetic Electron ◽  
Substorm Onset ◽  
Solar Wind Parameter ◽  
Ionospheric Conductivity ◽  
Coupling Parameters ◽  
Substorm Onsets

Abstract. Based on 1829 well-defined substorm onsets in the Northern Hemisphere, observed during a 2-year period by the FUV Imager on board the IMAGE spacecraft, a statistical study is performed. From the combination of solar wind parameter observations by ACE and magnetic field observations by the low altitude satellite CHAMP, the location of auroral breakups in response to solar illumination and solar coupling parameters are studied. Furthermore, the correspondence of the onset location with prominent large-scale field-aligned currents and electrojets are investigated. Solar illumination and the related ionospheric conductivity have significant effects on the most probable substorm onset latitude and local time. In sunlight, substorm onsets tend to occur 1h earlier in local time and 1.5° more poleward than in darkness. The solar wind input, represented by the merging electric field, integrated over 1h prior to the substorm, correlates well with the latitude of the breakup. Most poleward latitudes of the onsets are found to range around 73° magnetic latitude during very quiet times. Field-aligned and Hall currents observed concurrently with the onset are consistent with the signature of a westward travelling surge evolving out of the Harang discontinuity. The observations suggest that the ionospheric conductivity has an influence on the location of the precipitating energetic electron which causes the auroral break-up signature. Keywords. Ionosphere (Auroral ionosphere) – Magnetospheric Physics (Current systems; Magnetosphereionosphere interactions)

scholarly journals Astrid-2 and ground-based observations of the auroral bulge in the middle of the nightside convection throat

2001 ◽  
Vol 19 (6) ◽  
pp. 633-641 ◽  
Author(s):  
G. T. Marklund ◽  
T. Karlsson ◽  
P. Eglitis ◽  
H. Opgenoorth
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Large Scale ◽  
Current Model ◽  
Energetic Electron ◽  
Auroral Oval ◽  
Plasma Convection ◽  
Magnetometer Data ◽  
Electric Fields And Currents ◽  
Good Agreement

Abstract. Results concerning the electrodynamics of the nightside auroral bulge are presented based on simultaneous satellite and ground-based observations. The satellite data include Astrid-2 measurements of electric fields, currents and particles from a midnight auroral oval crossing and Polar UVI images of the large-scale auroral distribution. The ground-based observations include STARE and SuperDARN electric fields and magnetic records from the Greenland and MIRACLE magnetometer network, the latter including stations from northern Scandinavia north to Svalbard. At the time of the Astrid-2 crossing the ground-based data reveal intense electrojet activity, both to the east and west of the Astrid-2 trajectory, related to the Polar observations of the auroral bulge but not necessarily to a typical substorm. The energetic electron fluxes measured by Astrid-2 across the auroral oval were generally weak being consistent with a gap observed in the auroral luminosity distribution. The electric field across the oval was directed westward, intensifying close to the poleward boundary followed by a decrease in the polar cap. The combined observations suggests that Astrid-2 was moving close to the separatrix between the dusk and dawn convection cells in a region of low conductivity. The constant westward direction of the electric field across the oval indicates that current continuity was maintained, not by polarisation electric fields (as in a Cowling channel), but solely by localized up- and downward field-aligned currents in good agreement with the Astrid-2 magnetometer data. The absence of a polarisation electric field and thus of an intense westward closure current between the dawn and dusk convection cells is consistent with the relatively weak precipitation and low conductivity in the convection throat. Thus, the Cowling current model is not adequate for describing the electrodynamics of the nightside auroral bulge treated here.Key words. Ionosphere (auroral ionosphere; electric fields and currents; plasma convection)

scholarly journals Magnetic-local-time dependency of radiation belt electron precipitation: impact on ozone in the polar middle atmosphere

2021 ◽  
Author(s):  
Pekka T. Verronen ◽  
Daniel R. Marsh ◽  
Monika E. Szeląg ◽  
Niilo Kalakoski
Keyword(s):  
Local Time ◽  
Radiation Belt ◽  
Climate Model ◽  
Middle Atmosphere ◽  
Energetic Electron ◽  
Magnetic Local Time ◽  
Local Times ◽  
Ongoing Research ◽  
Diurnal Variability ◽  
Climate Simulations

<div> <div> <div> <p>The radiation belts are regions in the near-Earth space where solar wind electrons are captured by the Earth’s magnetic field. A portion of these electrons is continuously lost into the atmosphere where they cause ionization and chemical changes. Driven by the solar activity, the electron forcing leads to ozone variability in the polar stratosphere and mesosphere. Understanding the possible dynamical connections to regional climate is an ongoing research activity which supports the assessment of greenhouse-gas-driven climate change by a better definition of the solar-driven variability. In the context of the Coupled Model Intercomparison Project Phase 6 (CMIP6), energetic electron and proton precipitation is included in the solar-forcing recommendation for the first time. For the radiation belt electrons, the CMIP6 forcing is from a daily zonal-mean proxy model. This zonal-mean model ignores the well-known dependency of precipitation on magnetic local time (MLT), i.e. its diurnal variability. Here we use the Whole Atmosphere Community Climate Model with its lower-ionospheric-chemistry extension (WACCM-D) to study effects of the MLT dependency of electron forcing on the polar-ozone response. We analyse simulations applying MLT-dependent and MLT-independent forcings and contrast the resulting ozone responses in monthly-mean data as well as in monthly means at individual local times. We consider two cases: (1) the year 2003 and (2) an extreme, continuous forcing. Our results indicate that the ozone responses to the MLT-dependent and the MLT-independent forcings are very similar, and the differences found are small compared to those caused by the overall uncertainties related to the representation of electron forcing in climate simulations. We conclude that the use of daily zonal-mean electron forcing will provide an accurate ozone response in long-term climate simulations.</p> </div> </div> </div>

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