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L. L. Lazutin - One of the best experts on this subject based on the ideXlab platform.
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Injection of relativistic electrons into the internal magnetosphere during Magnetic Storms: Connection with subStorms
Geomagnetism and Aeronomy, 2013Co-Authors: L. L. LazutinAbstract:The connection between rapid increases in the intensity of electrons with energies >0.3 MeV and magnetospheric subStorms was studied for the first time by measurements of energetic electrons on the low-orbit SERVIS-1 satellite. In addition to the well-known process of radial diffusion detected at the recovery phase, the increases during a period of time no longer than 1.5 h at the main phase of six Magnetic Storms in a channel of 0.3–1.7 MeV (in three of them, in a channel of 1.7–3.4 MeV) were measured. An analysis of auroral zone magnetograms demonstrated that the increases occurred at the instant of magnetospheric substorm activation. A conclusion is made that the increases are caused by the radial injection of electrons by a pulse electric field induced during substorm activations. Pulse injections are shown to be one of the main mechanisms of electron radiation belt completion in the inner magnetosphere and, in combination with moderate radial diffusion, to be responsible for the appearance of large fluxes of energetic electrons (“killers”) in the magnetosphere after Magnetic Storms.
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Relaxation of electron and proton radiation belts of the earth after strong Magnetic Storms
Cosmic Research, 2012Co-Authors: L. L. Lazutin, Yu. I. Logachev, E. A. Muravieva, V. L. PetrovAbstract:During strong Magnetic Storms in July and November of 2004 the fluxes of trapped particles (protons and electrons of MeV energies) in the Earth’s radiation belts have increased by orders of magnitude and then decreased remaining on an enhanced level for several months. These enhancements allowed us to study the processes of relaxation of the radiation belts. Measurements of energetic particles by low-altitude satellites Coronas-F and Servis-1 have shown that predictions of the theory about the rate of pitch-angle diffusion are not always correct, giving both overestimated and underestimated values for the lifetime of energetic particles.
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on radiation belt dynamics during Magnetic Storms
Advances in Space Research, 2012Co-Authors: L. L. LazutinAbstract:Abstract Temporal variations of the radiation belt particle during the Magnetic Storms are investigated using measurements by the low altitude satellite spectrometer. Along with several known effects, such as the outer radiation belt intensity decrease at the main phase, the radial diffusion with the particle acceleration and the recovery of the radiation belt during the recovery phase, some less known features were investigated, such as the dawn–dusk asymmetry of the radiation belt. During the main phase in the dusk sector an extension of the outer Magnetic field lines into magnetotail occurs, the electron flux previously measured in the outer radiation belt maximum decreases to the polar cap level. All three adiabatic invariants remain conserved during this transformation and as a consequence the radiation belt became adiabatically shifted to the lower latitudes with addition of the nonadiabatic radial displacement. During the main phase in the dawn sector the chain of the substorm dipolarizations is acting against the tailward Magnetic field line extension produced by the ring current and satellite registers an enhanced particle flux in the quasitrapping region. The adiabatic recovery of the radiation belt take place at the end of the Magnetic storm again with the addition of the nonadiabatic effects caused by the substorm activity. It seems that a essential part of the radiation belt temporal dynamics during Magnetic Storms may be explained by the change of the Magnetic field configuration and the adiabatic effects. Together with the nonadiabatic radial diffusion it results in the radial displacement of the outer radiation belt rather than the large losses or total disappearance of the outer radiation belt.
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dynamics of solar protons in the earth s magnetosphere during Magnetic Storms in november 2004 january 2005
Geomagnetism and Aeronomy, 2010Co-Authors: L. L. Lazutin, M. I. Panasyuk, L. I. Starostin, Nobuyuki Hasebe, I N Myagkova, Yu B Yushkov, E A Muraveva, K Kudela, Yu. V. Gotselyuk, K. SukuraiAbstract:The processes of penetration, trapping, and acceleration of solar protons in the Earth’s magneto-sphere during Magnetic Storms in November 2004 and January 2005 are studied based on the energetic particle measurements on the CORONAS-F and SERVIS-1 satellites. Acceleration of protons by 1–2 orders of magnitude was observed after trapping of solar protons with an energy of 1–15 MeV during the recovery phase of the Magnetic storm of November 7–8, 2004. This acceleration was accompanied by an earthward shift of the particle flux maximum for several days, during which the series of Magnetic Storms continued. The process of relativistic electron acceleration proceeded simultaneously and according to a similar scenario including acceleration of protons. At the end of this period, the intensification was terminated by the process of precipitation, and a new proton belt split with the formation of two maximums at L ∼ 2 and 3. In the January 2005 series of moderate Storms, solar protons were trapped at L = 3.7 during the storm of January 17–18. However, during the Magnetic storm of January 21, these particles fell in the zone of quasi-trapping, or precipitated into the atmosphere, or died in the magnetosheath. At the same time, the belts that were formed in November at L ∼ 2 and 3 remained unchanged. Transformations of the proton (and electron) belts during strong Magnetic Storms change the intensity and structure of belts for a long time. Thus, the consequences of changes during the July 2004 storm did not disappear until November disturbances.
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Dynamics of solar protons in the Earth’s magnetosphere during Magnetic Storms in November 2004–January 2005
Geomagnetism and Aeronomy, 2010Co-Authors: L. L. Lazutin, M. I. Panasyuk, L. I. Starostin, I N Myagkova, K Kudela, Yu. V. Gotselyuk, E. A. Murav’eva, B. Yu. Yushkov, N. Hasebe, K. SukuraiAbstract:The processes of penetration, trapping, and acceleration of solar protons in the Earth’s magneto-sphere during Magnetic Storms in November 2004 and January 2005 are studied based on the energetic particle measurements on the CORONAS-F and SERVIS-1 satellites. Acceleration of protons by 1–2 orders of magnitude was observed after trapping of solar protons with an energy of 1–15 MeV during the recovery phase of the Magnetic storm of November 7–8, 2004. This acceleration was accompanied by an earthward shift of the particle flux maximum for several days, during which the series of Magnetic Storms continued. The process of relativistic electron acceleration proceeded simultaneously and according to a similar scenario including acceleration of protons. At the end of this period, the intensification was terminated by the process of precipitation, and a new proton belt split with the formation of two maximums at L ∼ 2 and 3. In the January 2005 series of moderate Storms, solar protons were trapped at L = 3.7 during the storm of January 17–18. However, during the Magnetic storm of January 21, these particles fell in the zone of quasi-trapping, or precipitated into the atmosphere, or died in the magnetosheath. At the same time, the belts that were formed in November at L ∼ 2 and 3 remained unchanged. Transformations of the proton (and electron) belts during strong Magnetic Storms change the intensity and structure of belts for a long time. Thus, the consequences of changes during the July 2004 storm did not disappear until November disturbances.
Kyung-chan Kim - One of the best experts on this subject based on the ideXlab platform.
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Revisit of relationship between geosynchronous relativistic electron enhancements and Magnetic Storms
Geophysical Research Letters, 2015Co-Authors: Hee-jeong Kim, L. Lyons, Victor A. Pinto, Chih-ping Wang, Kyung-chan KimAbstract:We find evidence that Magnetic Storms are not only unnecessary for geosynchronous relativistic electron enhancements but also not directly relevant to the electron enhancements even if the enhancements are accompanied by Magnetic Storms. What is crucial for electron enhancements at geosynchronous orbit are sustained south-oriented or north-south fluctuating interplanetary Magnetic field (IMF) Bz that drives sufficiently large substorm activity and small solar wind density Nsw that likely leads to low loss rate of relativistic electrons to the ionosphere and/or to the magnetopause for an extended time period. Specifically, almost all the abrupt, large electron increases in our data set took place under the condition of average AE > 235 nT and average Nsw ≤ 5 cm−3. Examination of detailed time profiles clearly shows that electron flux starts to increase quite immediately with arrival of the right IMF and solar wind conditions, regardless of a Magnetic storm, leaving the accompanied Magnetic Storms merely coincident.
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relativistic radiation belt electron responses to gem Magnetic Storms comparison of crres observations with 3 d verb simulations
Journal of Geophysical Research, 2012Co-Authors: Kyung-chan Kim, Yuri Shprits, D SubbotinAbstract:[1] Understanding the dynamics of relativistic electron acceleration, loss, and transport in the Earth's radiation belt during Magnetic Storms is a challenging task. The U.S. National Science Foundation's Geospace Environment Modeling (GEM) has identified five Magnetic Storms for in-depth study that occurred during the second half of the Combined Release and Radiation Effects Satellite (CRRES) mission in the year 1991. In this study, we show the responses of relativistic radiation belt electrons to the Magnetic Storms by comparing the time-dependent 3-D Versatile Electron Radiation Belt (VERB) simulations with the CRRES MEA 1 MeV electron observations in order to investigate the relative roles of the competing effects of previously proposed scattering mechanisms at different storm phases, as well as to examine the extent to which the simulations can reproduce observations. The major scattering processes in our model are radial transport due to Ultra Low Frequency (ULF) electroMagnetic fluctuations, pitch angle and energy diffusion including mixed diffusion by whistler mode chorus waves outside the plasmasphere, and pitch angle scattering by plasmaspheric hiss inside the plasmasphere. The 3-D VERB simulations show that during the storm main phase and early recovery phase the estimated plasmapause is located deep in the inner region, indicating that pitch angle scattering by chorus waves can be a dominant loss process in the outer belt. We have also confirmed the important role played by mixed energy-pitch angle diffusion by chorus waves, which tends to reduce the fluxes enhanced by local acceleration, resulting in comparable levels of computed and measured fluxes. However, we cannot reproduce the more pronounced flux dropout near the boundary of our simulations during the main phase, which indicates that non-adiabatic losses may extend toL-shells lower than our simulation boundary. We also provide a detailed description of simulations for each of the GEM storm events.
Yohsuke Kamide - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Storms current understanding and outstanding questions
Geophysical monograph, 2013Co-Authors: Yohsuke Kamide, Walter D. Gonzalez, Robert L. Mcpherron, D. C. Hamilton, Hugh S. Hudson, J. A. Joselyn, S. W. Kahler, H. Lundstedt, L R Lyons, E. SzuszczewiczAbstract:There is much evidence in recent Yohkoh and Ulysses observations that the most intense Magnetic Storms are a manifestation of fast Magnetic clouds, perhaps originating in Coronal Mass Ejections (CMEs). However, uncertainties exist as to what Magnetic configuration is formed for CMEs and how it changes over time, how CMEs interact with the interplanetary medium, and how geoeffectiveness depends on the different size of ejections. The constituents of the ring current in the magnetosphere as a function of storm time are now observationally identified. In particular, the ionospheric component shows the largest increase at L < 4 during the main phase of Magnetic Storms, indicating that the frequent occurrence of intense subStorms is important. There seems to be a consensus that, of the two processes playing essential roles in enhancing the storm-time ring current, the enhanced electric field driven by southward interplanetary Magnetic fields dominates the effects of the induced electric field resulting from substorm expansion onsets. This creates a new controversy regarding the relative importance of the two processes, although they are not mutually exclusive. There is a need to evaluate observations and models in kinetic, chemical, and electrodynamic coupling between the ionospheric and thermospheric Magnetic Storms in a more quantitative manner. For example, global, not regional, observations of the electron density and the neutral wind are required in order to understand the ionospheric/thermospheric Storms within the framework of the chain of processes from the Sun to the Earth. In view of the important effects of Magnetic Storms on a wide variety of human-societal systems, prediction schemes continue to be upgraded.
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Study of the Dst-AL correlation during geospace Magnetic Storms
IEEE Transactions on Plasma Science, 2004Co-Authors: F.-a. Metallinou, Yohsuke Kamide, Ioannis A. Daglis, John H. SeiradakisAbstract:A dispute on the role of subStorms in geospace Magnetic storm development has emerged during the last decade; the scientific community has not yet reached a definite conclusion. This paper attempts to clarify, to the extent possible with statistical methods, if there is any causal relationship between the energy dissipation during Storms and during subStorms. To assess this aspect of the storm-substorm relationship, we performed an investigation using the geoMagnetic indexes SYM-H and AL for a large number of Magnetic Storms. We selected a group of 53 Magnetic Storms with SYM-H peak values in the range between -50 nT and -350 nT. We then calculated the integrals of the SYM-H and AL squares, to represent Magnetic energy dissipation for Storms and subStorms respectively. These integrals exhibit a strong linear correlation, with a correlation index of r=0.928. The result implies a strong coupling between storm and substorm energy dissipation.
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Interplanetary Causes of Very Intense Magnetic Storms
1998Co-Authors: Walter D. Gonzalez, Bruce T. Tsurutani, Yohsuke Kamide, A. L. Clua De Gonzalez, A. Dal Lago, John K. ArballoAbstract:In this paper we examine the causes of largest Magnetic Storms at Earth (as measured by Dst). Possible interplanetary mechanisms for the creation of very intense Magnetic Storms are discussed.
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current understanding of Magnetic Storms storm substorm relationships
Journal of Geophysical Research, 1998Co-Authors: Yohsuke Kamide, Walter D. Gonzalez, Robert L. Mcpherron, J. A. Joselyn, W Baumjohann, I A Daglis, M Grande, J L Phillips, E G D Reeves, G RostokerAbstract:This paper attempts to summarize the current understanding of the storm/substorm relationship by clearing up a considerable amount of controversy and by addressing the question of how solar wind energy is deposited into and is dissipated in the constituent elements that are critical to magnetospheric and ionospheric processes during Magnetic Storms. (1) Four mechanisms are identified and discussed as the primary causes of enhanced electric fields in the interplanetary medium responsible for geoMagnetic Storms. It is pointed out that in reality, these four mechanisms, which are not mutually exclusive, but interdependent, interact differently from event to event. Interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs) are found to be the primary phenomena responsible for the main phase of geoMagnetic Storms. The other two mechanisms, i.e., HILDCAA (high-intensity, long-duration, continuous auroral electrojet activity) and the so-called Russell-McPherron effect, work to make the ICME and CIR phenomena more geoeffective. The solar cycle dependence of the various sources in creating Magnetic Storms has yet to be quantitatively understood. (2) A serious controversy exists as to whether the successive occurrence of intense subStorms plays a direct role in the energization of ring current particles or whether the enhanced electric field associated withmore » southward IMF enhances the effect of substorm expansions. While most of the {ital Dst} variance during Magnetic Storms can be solely reproduced by changes in the large-scale electric field in the solar wind and the residuals are uncorrelated with subStorms, recent satellite observations of the ring current constituents during the main phase of Magnetic Storms show the importance of ionospheric ions. This implies that ionospheric ions, which are associated with the frequent occurrence of intense subStorms, are accelerated upward along Magnetic field lines, contributing to the energy density of the storm-time ring current. An apparently new controversy regarding the relative importance of the two processes is thus created. It is important to identify the role of substorm occurrence in the large-scale enhancement of magnetospheric convection driven by solar wind electric fields. (3) Numerical schemes for predicting geoMagnetic activity indices on the basis of solar/solar wind/interplanetary Magnetic field parameters continue to be upgraded, ensuring reliable techniques for forecasting Magnetic Storms under real-time conditions. There is a need to evaluate the prediction capability of geoMagnetic indices on the basis of physical processes that occur during storm time subStorms. (4) It is crucial to differentiate between Storms and nonstorm time subStorms in terms of energy transfer/conversion processes, i.e., mechanical energy from the solar wind, electroMagnetic energy in the magnetotail, and again, mechanical energy of particles in the plasma sheet, ring current, and aurora. To help answer the question of the role of subStorms in energizing ring current particles, it is crucial to find efficient magnetospheric processes that heat ions up to some minimal energies so that they can have an effect on the strength of the storm time ring current. (5) The question of whether the {ital Dst} index is an accurate and effective measure of the storm time ring-current is also controversial. In particular, it is demonstrated that the dipolarization effect associated with substorm expansion acts to reduce the {ital Dst} magnitude, even though the ring current may still be growing. {copyright} 1998 American Geophysical Union« less
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Magnetic Storms - Magnetic Storms: Current Understanding and Outstanding Questions
Magnetic Storms, 1997Co-Authors: Yohsuke Kamide, Walter D. Gonzalez, Robert L. Mcpherron, D. C. Hamilton, Hugh S. Hudson, J. A. Joselyn, S. W. Kahler, L. Lyons, H. Lundstedt, E. SzuszczewiczAbstract:There is much evidence in recent Yohkoh and Ulysses observations that the most intense Magnetic Storms are a manifestation of fast Magnetic clouds, perhaps originating in Coronal Mass Ejections (CMEs). However, uncertainties exist as to what Magnetic configuration is formed for CMEs and how it changes over time, how CMEs interact with the interplanetary medium, and how geoeffectiveness depends on the different size of ejections. The constituents of the ring current in the magnetosphere as a function of storm time are now observationally identified. In particular, the ionospheric component shows the largest increase at L < 4 during the main phase of Magnetic Storms, indicating that the frequent occurrence of intense subStorms is important. There seems to be a consensus that, of the two processes playing essential roles in enhancing the storm-time ring current, the enhanced electric field driven by southward interplanetary Magnetic fields dominates the effects of the induced electric field resulting from substorm expansion onsets. This creates a new controversy regarding the relative importance of the two processes, although they are not mutually exclusive. There is a need to evaluate observations and models in kinetic, chemical, and electrodynamic coupling between the ionospheric and thermospheric Magnetic Storms in a more quantitative manner. For example, global, not regional, observations of the electron density and the neutral wind are required in order to understand the ionospheric/thermospheric Storms within the framework of the chain of processes from the Sun to the Earth. In view of the important effects of Magnetic Storms on a wide variety of human-societal systems, prediction schemes continue to be upgraded.
R S Selesnick - One of the best experts on this subject based on the ideXlab platform.
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injection and loss of inner radiation belt protons during solar proton events and Magnetic Storms
Journal of Geophysical Research, 2010Co-Authors: R S Selesnick, M K Hudson, B T KressAbstract:[1] A survey of 27 to 45 MeV proton measurements from the HEO-3 satellite during the years 1998 through 2005 has been taken to describe variability in the outer part of the inner radiation belt and slot region (L = 2 to 3). Rapid (∼1-day) changes are described as injection or loss events, characterized respectively by Gaussian or exponential L dependencies. The radial extent of both event types is correlated to the minimum Dst of associated Magnetic Storms, while the injection magnitude is correlated to the flux of associated interplanetary solar proton events. Changes in the maximal L of observed trapped protons are consistent with trapping limits estimated from Magnetic field line curvature. The inward extent and energy independence of the observed loss events are inconsistent with field line curvature induced scattering in a static Magnetic field. However, time-dependent geoMagnetic cutoff suppression, observed during Magnetic Storms, may be the cause of significant losses. Drift resonance with electric field impulses caused by rapid magnetospheric compression is the likely cause of both solar proton injections and radial shifts of preexisting trapped protons.
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source and loss rates of radiation belt relativistic electrons during Magnetic Storms
Journal of Geophysical Research, 2006Co-Authors: R S SelesnickAbstract:[1] A numerical model of the radiation belt electron distribution as a function of equatorial pitch angle, longitude, and time is combined with data from a low-altitude satellite to estimate the source and loss rates of ∼0.5 to 3 MeV electrons during Magnetic Storms. The relative intensity levels in the stable trapping and drift loss cone regions provide a measure of the loss rate and associated pitch angle diffusion coefficient. The source rate is that required to maintain the observed stably trapped component. The source mechanism is unspecified and may include a combination of radial diffusion and local acceleration. Adiabatic effects are treated separately and are found to have a minimal influence on parameter estimation in the presence of pitch angle diffusion. Two sample storm periods provide examples of the varying source and loss rates estimated with this method. They show that significant losses during the storm main phase deplete the prestorm radiation belt on a timescale ∼1 hour. It is replenished by a source that acts concurrently or at somewhat later times. Significant but variable source and loss processes may continue during the storm recovery phase. The storm time source and loss rates may result in a net increase or decrease in the stably trapped population relative to the prestorm level. These conclusions are supported by source and loss indices that are defined to provide rough estimates of the fractional source and loss rates from several additional Magnetic Storms and are readily calculated from the data alone.
Chinliang Wang - One of the best experts on this subject based on the ideXlab platform.
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simultaneous observations of plasmaspheric and ionospheric variations during Magnetic Storms in 2011 first result from chinese meridian project
Journal of Geophysical Research, 2013Co-Authors: Chinliang Wang, Qingmei Zhang, P J ChiAbstract:The plasma transport between the plasmasphere and ionosphere during Magnetic Storms is a long-standing problem and is still not fully understood. Simultaneous observations of the plasmasphere and ionosphere are vital to understand the coupling between the two regions. In this study, using the measurements from the newly developed Chinese ground-based space weather monitoring network (Meridian Project), we investigate the plasmaspheric density at L ≃ 2 inferred from ground magnetometers and the ionospheric electron density inferred by digital ionosondes and GPS signals during Magnetic Storms in 2011. Five moderate Magnetic Storms with minimum Dst index between −47 and −103 nT during this period have been investigated. The observations show that the plasmaspheric density drops significantly by more than half of the prestorm value. The ionospheric F2 layer electron density NmF2 and the total electron content (TEC) show ~20–50% decreases, and the NmF2 and TEC reductions take place before the plasmaspheric density reaches its minimum. These findings suggest that the plasmaspheric depletion is very likely due to the reduced plasma supply from the ionosphere for the five moderate Magnetic Storms in 2011. Therefore, the plasmasphere dynamics seems to be controlled by the ionosphere during Magnetic Storms.
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contribution of the partial ring current to the symh index during Magnetic Storms
Journal of Geophysical Research, 2011Co-Authors: Chinliang Wang, J R KanAbstract:To identify which magnetospheric current system contributes the most to the SYMH index during Magnetic Storms, we performed a statistical analysis of 299 Magnetic Storms from 1996 to 2006 and investigated the distribution of the H depressions with Magnetic local times (MLT), by using data from 25 geoMagnetic stations distributed almost uniformly in Magnetic longitudes over Magnetic latitudes ranging from 9 degrees to 45 degrees. As expected, a significant dawn-dusk asymmetry of H depression during the storm main phase and early recovery phase reveals the importance of the partial ring current during Magnetic storm processes. The location, evolution, and quantitative contribution of the partial ring current during Magnetic Storms with different intensities are all further obtained. The partial ring current locates in the dusk sector, peaking in 18:00 similar to 20:00 MLT. It forms in the early main phase, increases gradually until the SYMH index reaches its minimum, and then quickly decreases in the recovery phase. The contribution of the partial ring current weakens gradually as the storm intensity increases. For moderate (-100 < SYMH <= -50 nT) and intense (-300 < SYMH <= -100 nT) Storms, the partial ring current is the predominant contributor during the main phase. However, the partial ring current is no longer the predominant contributor for the super Storms with SYMH <= -300 nT, which may suggest the saturation of the partial ring current under extreme solar wind conditions.