Jose Paulo Marchezi
@eos.unh.edu
Postdoctoral Research Associate
University of New Hampshire
RESEARCH, TEACHING, or OTHER INTERESTS
Space and Planetary Science, Physics and Astronomy, Geophysics, General Physics and Astronomy
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
L. A. Da Silva, J. Shi, J. P. Marchezi, O. V. Agapitov, D. Sibeck, L. R. Alves, L. E. A. Vieira, V. Deggeroni, L. C. A. Resende, R. Lopez,et al.
American Geophysical Union (AGU)
AbstractThe high‐energy electron flux enhancement pattern in the outer radiation belt is observed under the influence of the Interplanetary Coronal Mass Ejections (ICMEs). Ten events were selected during the Van Allen Probes era, with the high‐energy electron flux enhancement starting close to L* = 4. A schematic diagram of the main physical processes responsible for this kind of high‐energy electron flux enhancement is presented, considering the energy deposited in the inner magnetosphere under the influence of ICMEs. Superposed Epoch Analysis is applied to the interplanetary medium parameters, the magnetopause standoff distance, the storm‐time geomagnetic activity indices, the Ultra‐Low Frequency (ULF) waves, and the whistler‐mode chorus waves. A compressed magnetopause, Bz component preferentially southward and storm indices considerably high are observed at the beginning of the electron flux enhancements. The modeled parameters of the chorus waves at the dayside/nightside sectors show the high acceleration efficiency at the beginning of the electron flux enhancement pattern II. These results suggest that the local acceleration driven by chorus waves is essential to these electron flux enhancements at low L*. In contrast, although the ULF waves are detected at the beginning of the studied electron flux enhancements, their contribution is insignificant.
S. S. Chen, L. C. A. Resende, C. M. Denardini, R. A. J. Chagas, L. A. Da Silva, J. P. Marchezi, J. Moro, P. A. B. Nogueira, A. M. Santos, P. R. Jauer,et al.
American Geophysical Union (AGU)
AbstractWe discuss the effects in the geomagnetic field variations and ionospheric plasma density modifications caused by the Total Solar Eclipse that occurred on 14 December 2020 over the South American sector. We used ground‐based magnetometer data and the Total Electron Content maps derived from the Global Navigation Satellite System to evaluate these changes. The results show that the geomagnetic field daily variation weakens between the first and last solar eclipse penumbra contact. Additionally, we observed a significant reduction of about 52.33 nT on the Equatorial Electrojet strength at Jicamarca (11.95°S, 76.88°W), where the solar obscuration reached 16.67% approximately. This behavior indicates that the solar eclipse in the equatorial region has possibly affected electric conductivities, altering the E region dynamo electric field. Consequently, it weakens the equatorial plasma fountain, affecting the Equatorial Ionization Anomaly development. Additionally, the ionospheric dynamics variations over Jicamarca during the solar eclipse event are analyzed using ionosonde data. We observe that the solar eclipse also caused a modification in the sporadic E layer and F region dynamics, indicating possible evidence of the gravity wave occurrence. Therefore, the results found here provide a better understanding of how the solar eclipse passage in the equatorial region affects the electron density in the low‐latitude regions.
L. A. Da Silva, J. Shi, L. E. Vieira, O. V. Agapitov, L. C. A. Resende, L. R. Alves, D. Sibeck, V. Deggeroni, J. P. Marchezi, S. Chen,et al.
Frontiers Media SA
The low-electron flux variability (increase/decrease) in the Earth’s radiation belts could cause low-energy Electron Precipitation (EP) to the atmosphere over auroral and South American Magnetic Anomaly (SAMA) regions. This EP into the atmosphere can cause an extra upper atmosphere’s ionization, forming the auroral-type sporadic E layers (Esa) over these regions. The dynamic mechanisms responsible for developing this Esa layer over the auroral region have been established in the literature since the 1960s. In contrast, there are several open questions over the SAMA region, principally due to the absence (or contamination) of the inner radiation belt and EP parameter measurements over this region. Generally, the Esa layer is detected under the influence of geomagnetic storms during the recovery phase, associated with solar wind structures, in which the time duration over the auroral region is considerably greater than the time duration over the SAMA region. The inner radiation belt’s dynamic is investigated during a High-speed Solar wind Stream (September 24-25, 2017), and the hiss wave-particle interactions are the main dynamic mechanism able to trigger the Esa layer’s generation outside the auroral oval. This result is compared with the dynamic mechanisms that can cause particle precipitation in the auroral region, showing that each region presents different physical mechanisms. Additionally, the difference between the time duration of the hiss wave activities and the Esa layers is discussed, highlighting other ingredients mandatory to generate the Esa layer in the SAMA region.
L. C. A. Resende, Y. Zhu, C. M. Denardini, R. A. J. Chagas, L. A. Da Silva, V. F. Andrioli, C. A. O. Figueiredo, J. P. Marchezi, S. S. Chen, J. Moro,et al.
Frontiers Media SA
We present a study about the atypical and spreading Sporadic E-layers (Es) observed in Digisonde data. We analyzed a set of days around space weather events from 2016 to 2018 over Cachoeira Paulista (CXP, 22.41°S, 45°W, dip ∼35°), a low-latitude Brazilian station. The inhomogeneous Es layer is associated with the auroral-type Es layer (Esa) occurrence in this region due to the presence of South American Magnetic Anomaly (SAMA). However, we also observe that the spreading Es layers occurred days before the magnetic storms or quiet times. Also, this specific type of Es layer has some different characteristics concerning the Esa layer. We used data from the imager, satellite, and meteor radar to understand the dynamic processes acting in this Es layer formation. Our results lead us to believe that other mechanisms affect the Es layer development. We show evidence that the instabilities added to the wind shear mechanism can cause the atypical Es layers, such as Kelvin-Helmholtz instability (KHI). Finally, an important discovery of this work is that the spreading Es layer, mainly during quiet times, is not necessarily due to the particle precipitation due to the SAMA. We found that the wind shear can be turbulent, influencing the Es layer development. Lastly, our analysis better understood the Es layer behavior during quiet and disturbed times.
L.C.A. Resende, Y. Zhu, C.M. Denardini, J. Moro, L.A. Da Silva, C. Arras, R.A.J. Chagas, S.S. Chen, J.P. Marchezi, C.S. Carmo,et al.
Elsevier BV
P. R. Jauer, C. Wang, E. Echer, V. M. Souza, L. A. Da Silva, J. P. Marchezi, L. R. Alves, M. V. Alves, S. Douglas, C. Loesch,et al.
American Geophysical Union (AGU)
AbstractThe interaction and response of the magnetic cloud‐type structure with Earth's magnetosphere were modeled by the SWMF/BATS‐R‐US code. The conversion of magnetic (Em), kinetic (Ek), and internal (Ei) energies was analyzed as well as the wave power integrated in the ultra‐low frequency (ULF) range of the poloidal (Eϕ) and toroidal (Er) electric field components in the equatorial region of the magnetosphere, in seven 2‐hr long intervals, namely, I1 through I7. The intensity of energy conversion and wave activity for I1 and I7 intervals was negligible. The energy conversion started in the I2 interval and extended to the I3, I4, and I5 intervals. The power of the Eϕ and Er components in the dayside and nightside regions is clearly observed. The I4 corresponds to interplanetary magnetic field (IMF) Bz mostly southward and the I5 has similar amplitudes of the Bz and By components, corresponding to the period of the high geomagnetic activity. The conversion rate for the I4 and I5 was similar, however, the integrated power spectral density (IPSD) of the Eϕ and Er components is more intense in I5. During the I6 interval, with predominant IMF By, the energy conversion rate is intensified mostly for inner radial distances R < 6 RE, and the Ek component becomes close to zero for outer regions. The energy conversion regions are located spatially close to or overlapping with regions where the IPSD in the ULF range is intensified. The energy conversion in the inner magnetosphere occurred preferentially between Em and Ei, with the Ek energy component always present but with lower intensities.
Laysa C. A. Resende, Yajun Zhu, Christina Arras, Clezio M. Denardini, Sony S. Chen, Juliano Moro, Diego Barros, Ronan A. J. Chagas, Lígia A. Da Silva, Vânia F. Andrioli,et al.
MDPI AG
The development of sporadic-E (Es) layers over five Digisonde stations in the American sector is analyzed. This work aims to investigate the dynamic of such layers during the days around the geomagnetic storm that occurred on 8 September 2017. Therefore, a numerical model (MIRE) and Radio Occultation (RO) technique are used to analyze the E layer dynamics. The results show a downward movement in low-middle latitudes due to the wind components that had no significant changes before, during, and after the geomagnetic storm. In fact, our data and simulations showed weak Es layers over Boulder, Cachoeira Paulista, and Santa Maria, even though the winds were not low. However, the RO data show the terdiurnal and quarterdiurnal influence in the Es layer formation, which can explain this behavior. In addition, we observed an atypical Es layer type, slant Es layer (Ess), during the main phase of the magnetic storm over Boulder. The possible cause of the Ess layers was gravity waves. Another interesting point is the spreading Es layer occurrence associated with the Kelvin–Helmholtz Instability (KHI). Finally, it is confirmed that the disturbed electric field only influenced the Es layer dynamics in regions near the magnetic equator.
L. A. Da Silva, J Shi, L. C. A. Resende, O. V. Agapitov, L. R. Alves, I. S. Batista, C. Arras, L. E. Vieira, V. Deggeroni, J. P. Marchezi,et al.
Frontiers Media SA
The dynamics of the electron population in the Earth’s radiation belts affect the upper atmosphere’s ionization level through the low-energy Electron Precipitation (EP). The impact of low-energy EP on the high-latitude ionosphere has been well explained since the 1960’s decade. Conversely, it is still not well understood for the region of the South American Magnetic Anomaly (SAMA). In this study, we present the results of analysis of the strong geomagnetic storm associated with the Interplanetary Coronal Mass Ejection (May 27-28, 2017). The atypical auroral sporadic E layers (Esa) over SAMA are observed in concomitance with the hiss and magnetosonic wave activities in the inner radiation belt. The wave-particle interaction effects have been estimated, and the dynamic mechanisms that caused the low-energy EP over SAMA were investigated. We suggested that the enhancement in pitch angle scattering driven by hiss waves result in the low-energy EP (≥10 keV) into the atmosphere over SAMA. The impact of these precipitations on the ionization rate at the altitude range from 100 to 120 km can generate the Esa layer in this peculiar region. In contrast, we suggested that the low-energy EP (≤1 keV) causes the maximum ionization rate close to 150 km altitude, contributing to the Esa layer occurrence in these altitudes.
J. P. Marchezi, L. Dai, L. R. Alves, L. A. Da Silva, D. G. Sibeck, A. Dal Lago, V. M. Souza, P. R. Jauer, L. E. A. Veira, F. R. Cardoso,et al.
American Geophysical Union (AGU)
The ultra‐low frequency (ULF) waves can stochastically accelerate radiation belt electrons. Radial diffusion is a well‐established mechanism that can enhance or reduce the electron population in combination with other processes. Using data from the Van Allen Probes, we investigated the response of the 2.10 MeV energy electrons and ULF waves to two types of solar wind structures interacting with Earth's magnetosphere, namely, interplanetary coronal mass ejections (ICMEs) and High‐Speed solar wind streams (HSS). We use measured electron differential flux and ULF waves in the Pc4–Pc5 frequency range from October 2012 to May 2019. We examine 155 events with changes in the outer radiation belt electron differential flux. Results considering all ICMEs and HSSs during the Van Allen Probes era show that for both solar wind structures, solar wind interplanetary magnetic field Bz, solar wind proton density, and speed are related to the outer radiation belt relativistic electrons' response. The persistent ULF power is present during enhancement cases, while for reduction, the ULF waves power is concentrated at the initial reduction on the outer radiation belt electron flux.
Laysa C. A. Resende, Yajun Zhu, Clezio M. Denardini, Sony S. Chen, Ronan A. J. Chagas, Lígia A. Da Silva, Carolina S. Carmo, Juliano Moro, Diego Barros, Paulo A. B. Nogueira,et al.
Copernicus GmbH
Abstract. This work presents an analysis of the ionospheric responses to the solar eclipse that occurred on 14 December 2020 over the Brazilian sector. This event partially covers the south of Brazil, providing an excellent opportunity to study the modifications in the peculiarities that occur in this sector, as the equatorial ionization anomaly (EIA). Therefore, we used the Digisonde data available in this period for two sites: Campo Grande (CG; 20.47∘ S, 54.60∘ W; dip ∼23∘ S) and Cachoeira Paulista (CXP; 22.70∘ S, 45.01∘ W; dip ∼35∘ S), assessing the E and F regions and Es layer behaviors. Additionally, a numerical model (MIRE, Portuguese acronym for E Region Ionospheric Model) is used to analyze the E layer dynamics modification around these times. The results show the F1 region disappearance and an apparent electronic density reduction in the E region during the solar eclipse. We also analyzed the total electron content (TEC) maps from the Global Navigation Satellite System (GNSS) that indicate a weakness in the EIA. On the other hand, we observe the rise of the Es layer electron density, which is related to the gravity waves strengthened during solar eclipse events. Finally, our results lead to a better understanding of the restructuring mechanisms in the ionosphere at low latitudes during the solar eclipse events, even though they only partially reached the studied regions.
V. F. Andrioli, J. Xu, P. P. Batista, L. C. A. Resende, L. A. Da Silva, J. P. Marchezi, H. Li, C. Wang, Z. Liu, and A. Guharay
American Geophysical Union (AGU)
Mesospheric winds have been measured by meteor radar at Cachoeira Paulista (22.7°S; 45°W) since April 1999. The tidal components were analyzed over about 21 years of available data exhibiting an annual and semi‐annual variation. Amplitudes of meridional diurnal (semidiurnal) tide are on averaged 30% (28%) and the zonal ones are 14% (20%) stronger at solar minimum than at solar maximum. The anticorrelation between F10.7 cm solar flux and amplitudes of the semiannual oscillation of diurnal and semidiurnal tides is presented. Additionally, the sporadic E (Es) layers occurrence has an anti‐correlation with solar activity due to the tidal wind variation. A discussion about the physical mechanism is performed in terms of the particle precipitation during High‐Speed Stream (HSS) events according to the solar cycle. Finally, a superposed epoch analysis of the tidal amplitudes during the HSS events in 2018 is presented. And a slight increase in all tidal components is seen when the structure reached the Earth and in the following days showing that indeed the electron precipitation during HSS events affect the tidal amplitudes.
L. A. Da Silva, J. Shi, L. R. Alves, D. Sibeck, J. P. Marchezi, C. Medeiros, L. E. A. Vieira, O. Agapitov, F. R. Cardoso, V. M. Souza,et al.
Journal of Geophysical Research: Space Physics American Geophysical Union (AGU)
L. A. Da Silva, J. Shi, L. R. Alves, D. Sibeck, V. M. Souza, J. P. Marchezi, C. Medeiros, L. E. A. Vieira, O. Agapitov, P. R. Jauer,et al.
American Geophysical Union (AGU)
AbstractThe near‐Earth interplanetary environment conditions affect the dynamics of the relativistic electron population quasitrapped in the radiation belts. A complex chain of processes observed in the magnetosphere can contribute to the variability of these populations when interplanetary structures, such as the interplanetary counterpart of a solar coronal mass ejection (ICME), and high‐speed solar wind streams interact with the magnetosphere. However, as these processes can coexist, it is hard to untangle the relative contribution of each process to the loss of particles and the eventual repopulation. Here we show evidence that it is possible to distinguish the relative contribution of mechanisms related to the loss of the outer radiation belt electrons for an event observed on July 19 and 20, 2016. The interaction of an ICME's turbulent sheath with the Earth's magnetosphere resulted in a decrease in the outer radiation belt relativistic electron population. The ultralow frequency (ULF) and chorus wave activities are detected in the outer radiation belt during the time when the Earth's magnetosphere is under the influence of the ICME's sheath region, as well as the ICME's magnetic cloud region, while the electromagnetic ion cyclotron (EMIC) waves in the outer belt are observed only during the sheath region. Dynamic mechanisms such as magnetopause shadowing, outward radial diffusion driven by ULF waves, pitch‐angle scattering driven by both EMIC and chorus waves are quantitatively analyzed. Our results suggest that the structures of the ICMEs can trigger the drivers to generate the different dynamic mechanisms responsible for the radiation belt population variability.
Claudia Medeiros, V. M. Souza, L. E. A. Vieira, D. G. Sibeck, B. Remya, L. A. Da Silva, L. R. Alves, J. P. Marchezi, P. R. Jauer, M. Rockenbach,et al.
American Astronomical Society
Several studies have shown the importance of electromagnetic ion cyclotron (EMIC) waves to the pitch angle scattering of energetic particles in the radiation belt, especially relativistic electrons, thus contributing to their net loss from the outer radiation belt to the upper atmosphere. The huge amount of data collected thus far provides us with the opportunity to use a deep learning technique referred to as the Bag-of-Features (BoF). When applied to images of magnetic field spectrograms in the frequency range of EMIC waves, the BoF allows us to distinguish, in a semi-automated way, several patterns in these spectrograms that can be relevant to describe physical aspects of EMIC waves. Each spectrogram image provided as an input to the BoF corresponds to the windowed Fourier transform of a ∼40 minutes to 1 hour interval of Van Allen Probes’ high time-resolution vector magnetic field observations. Our data set spans the 2012 September 8 to 2016 December 31 period and is at geocentric distances larger than 3 Earth radii. A total of 66,204 spectrogram images are acquired in this interval, and about 45% of them, i.e., 30,190 images, are visually inspected to validate the BoF technique. The BoF’s performance in identifying spectrograms with likely EMIC wave signatures is comparable to the visual inspection method, with the enormous advantage that the BoF technique greatly expedites the analysis by accomplishing the task in just a few minutes.
P. R. Jauer, C. Wang, V. M. Souza, M. V. Alves, L. R. Alves, M. B. Pádua, J. P. Marchezi, Da L. A. Silva, Z. Liu, H. Li,et al.
American Astronomical Society
Abstract Using global magnetohydrodynamic (MHD) simulations, we investigate the role played by a complex solar structure composed of a corotating interaction region (CIR) followed by solar wind Alfvénic fluctuations on the magnetosphere’s nightside, equatorial electric field oscillations in the ultra-low-frequency range. A series of numerical experiments are performed employing synthetic solar wind inputs resembling those of a real CIR+Alfvénic fluctuation event that reached Earth’s magnetosphere on 2003 April 20. The following is found: (i) Radial electric field component fluctuations are excited via magnetopause boundary motions driven either by solar wind density variations characteristic of CIRs or by solar wind Alfvénic fluctuations with a given oscillation period. (ii) Azimuthal electric field component fluctuations nearer to Earth, that is, at radial distances R less than about 5R E ( Earth radius), are apparently not related to either of the two types of sinusoidal solar wind Alfvénic fluctuations used in this study featuring monochromatic frequencies of 0.833 mHz (20-minute period) and 1.666 mHz (10-minute period). Instead, these innermost azimuthal component fluctuations show enhanced activity when inner magnetosphere convection increases as a result of a southward turning of the interplanetary magnetic field component B z . (iii) Lastly, outermost (R ≳ 7 R E) azimuthal electric field oscillations weakly respond to monochromatic solar wind Alfvénic fluctuations by showing power spectral density peaks at both driving frequencies, but only near the flanks of the magnetopause, thus suggesting that such oscillations are being excited also owing to magnetopause boundary motions driven by solar wind Alfvénic fluctuations.
L. A. Da Silva, D. Sibeck, L. R. Alves, V. M. Souza, P. R. Jauer, S. G. Claudepierre, J. P. Marchezi, O. Agapitov, C. Medeiros, L. E. A. Vieira,et al.
American Geophysical Union (AGU)
Energy coupling between the solar wind and the Earth's magnetosphere can affect the electron population in the outer radiation belt. However, the precise role of different internal and external mechanisms that leads to changes of the relativistic electron population is not entirely known. This paper describes how ultralow frequency (ULF) wave activity during the passage of Alfvénic solar wind streams contributes to the global recovery of the relativistic electron population in the outer radiation belt. To investigate the contribution of the ULF waves, we searched the Van Allen Probes data for a period in which we can clearly distinguish the enhancement of electron fluxes from the background. We found that the global recovery that started on 22 September 2014, which coincides with the corotating interaction region preceding a high‐speed stream and the occurrence of persistent substorm activity, provides an excellent scenario to explore the contribution of ULF waves. To support our analyses, we employed ground‐ and space‐based observational data and global magnetohydrodynamic simulations and calculated the ULF wave radial diffusion coefficients employing an empirical model. Observations show a gradual increase of electron fluxes in the outer radiation belt and a concomitant enhancement of ULF activity that spreads from higher to lower L‐shells. Magnetohydrodynamic simulation results agree with observed ULF wave activity in the magnetotail, which leads to both fast and Alfvén modes in the magnetospheric nightside sector. The observations agree with the empirical model and are confirmed by phase space density calculations for this global recovery period.
Claudia Medeiros, V. M. Souza, L. E. A. Vieira, D. G. Sibeck, A. J. Halford, S.-B. Kang, L. A. Da Silva, L. R. Alves, J. P. Marchezi, R. S. Dallaqua,et al.
American Astronomical Society
Following the arrival of two interplanetary coronal mass ejections on 2014 September 12, the Relativistic Electron–Proton Telescope instrument on board the twin Van Allen Probes observed a long-term dropout in the outer belt electron fluxes. The interplanetary shocks compressed the magnetopause, thereby enabling the loss of relativistic electrons in the outer radiation belt to the magnetosheath region via the magnetopause shadowing. Previous studies have invoked enhanced radial transport associated with ultra-low-frequency waves activity and/or scattering into the atmosphere by whistler mode chorus waves to explain electron losses deep within the magnetosphere (L < 5.5). We show that energetic electron pitch angle distributions (PADs) provide strong evidence for precipitation also via interaction with electromagnetic ion cyclotron (EMIC) waves. High-resolution magnetic field observations on Van Allen Probe B confirm the sporadic presence of EMIC waves during the most intense dropout phase on September 12. Observational results suggest that magnetopause shadowing and EMIC waves together were responsible for reconfiguring the relativistic electron PADs into peculiar butterfly PAD shapes a few hours after an interplanetary shock arrived at Earth.
V. M. Souza, R. E. Lopez, P. R. Jauer, D. G. Sibeck, K. Pham, L. A. Da Silva, J. P. Marchezi, L. R. Alves, D. Koga, C. Medeiros,et al.
American Geophysical Union (AGU)
In this study we examine the recovery of relativistic radiation belt electrons on 15–16 November 2014, after a previous reduction in the electron flux resulting from the passage of a corotating interaction region (CIR). Following the CIR, there was a period of high‐speed streams characterized by large, nonlinear fluctuations in the interplanetary magnetic field (IMF) components. However, the outer radiation belt electron flux remained at a low level for several days before it increased in two major steps. The first increase is associated with the IMF background field turning from slightly northward on average to slightly southward on average. The second major increase is associated with an increase in the solar wind velocity during a period of southward average IMF background field. We present evidence that when the IMF Bz is negative on average, the whistler mode chorus wave power is enhanced in the outer radiation belt, and the amplification of magnetic integrated power spectral density in the ULF frequency range, in the nightside magnetosphere, is more efficient as compared to cases in which the mean IMF Bz is positive. Preliminary analysis of the time evolution of phase space density radial profiles did not provide conclusive evidence on which electron acceleration mechanism is the dominant. We argue that the acceleration of radiation belt electrons requires (i) a seed population of keV electrons injected into the inner magnetosphere by substorms and both (ii) enhanced whistler mode chorus waves activity as well as (iii) large‐amplitude MHD waves.
L. R. Alves, V. M. Souza, P. R. Jauer, L. A. da Silva, C. Medeiros, C. R. Braga, M. V. Alves, D. Koga, J. P. Marchezi, R. R. S. de Mendonça,et al.
Springer Science and Business Media LLC
L.A. Da Silva, P. Satyamurty, L.R. Alves, V.M. Souza, P.R. Jauer, M.V.D. Silveira, M.S. Echer, R. Hajra, C. Medeiros, J.P. Marchezi,et al.
Elsevier BV
V. M. Souza, L. E. A. Vieira, C. Medeiros, L. A. Da Silva, L. R. Alves, D. Koga, D. G. Sibeck, B. M. Walsh, S. G. Kanekal, P. R. Jauer,et al.
American Geophysical Union (AGU)
Analysis of particle pitch angle distributions (PADs) has been used as a means to comprehend a multitude of different physical mechanisms that lead to flux variations in the Van Allen belts and also to particle precipitation into the upper atmosphere. In this work we developed a neural network‐based data clustering methodology that automatically identifies distinct PAD types in an unsupervised way using particle flux data. One can promptly identify and locate three well‐known PAD types in both time and radial distance, namely, 90° peaked, butterfly, and flattop distributions. In order to illustrate the applicability of our methodology, we used relativistic electron flux data from the whole month of November 2014, acquired from the Relativistic Electron‐Proton Telescope instrument on board the Van Allen Probes, but it is emphasized that our approach can also be used with multiplatform spacecraft data. Our PAD classification results are in reasonably good agreement with those obtained by standard statistical fitting algorithms. The proposed methodology has a potential use for Van Allen belt's monitoring.
L. R. Alves, L. A. Da Silva, V. M. Souza, D. G. Sibeck, P. R. Jauer, L. E. A. Vieira, B. M. Walsh, M. V. D. Silveira, J. P. Marchezi, M. Rockenbach,et al.
American Geophysical Union (AGU)
Magnetopause shadowing and wave‐particle interactions are recognized as the two primary mechanisms for losses of electrons from the outer radiation belt. We investigate these mechanisms, using satellite observations both in interplanetary space and within the magnetosphere and particle drift modeling. Two interplanetary shocks/sheaths impinged upon the magnetopause causing a relativistic electron flux dropout. The magnetic cloud (MC) and interplanetary structure sunward of the MC had primarily northward magnetic field, perhaps leading to a concomitant lack of substorm activity and a 10 daylong quiescent period. The arrival of two shocks caused an unusual electron flux dropout. Test‐particle simulations have shown ∼ 2 to 5 MeV energy, equatorially mirroring electrons with initial values of L≥5.5 can be lost to the magnetosheath via magnetopause shadowing alone. For electron losses at lower L‐shells, coherent chorus wave‐driven pitch angle scattering and ULF wave‐driven radial transport have been shown to be viable mechanisms.