Sources, transport, and losses of energetic particles during geomagnetic storms

2005 ◽  
pp. 9-21 ◽  
Author(s):  
Vania K. Jordanova
Keyword(s):  
Geomagnetic Storms ◽  
Energetic Particles

Flux dropouts of plasma and energetic particles at geosynchronous orbit during large geomagnetic storms: Entry into the lobes

1995 ◽  
Vol 100 (A5) ◽  
pp. 8031 ◽  
Author(s):  
Mark B. Moldwin ◽  
Michelle F. Thomsen ◽  
Samuel J. Bame ◽  
David J. McComas ◽  
Joachim Birn ◽  
...  
Keyword(s):  
Geomagnetic Storms ◽  
Energetic Particles ◽  
Geosynchronous Orbit

scholarly journals Association of cusp energetic ions with geomagnetic storms and substorms

2012 ◽  
Vol 30 (12) ◽  
pp. 1633-1643 ◽  
Author(s):  
J. T. Niehof ◽  
S. K. Morley ◽  
R. H. W. Friedel
Keyword(s):  
Geomagnetic Storm ◽  
Geomagnetic Storms ◽  
Energetic Particles ◽  
Energetic Ions ◽  
Significant Dependence ◽  
Substorm Activity ◽  
Storms And Substorms ◽  
Magnetospheric Dynamics ◽  
Substorm Onsets ◽  
Polar Satellite

Abstract. Energetic ions observed in the cusp have been explained as a result of processes within the magnetosphere, but also proposed as a driver of some of those same processes. This study assesses potential connections between energetic ions observed in the cusp and geomagnetic storm and substorm activity. These connections may suggest sources of cusp energetic particles (CEPs), or imply effects of these particles on magnetospheric dynamics. We identify CEPs from six years of cusp crossings by the Polar satellite, relating them to storm and substorm onsets. CEPs showed no significant dependence on storms but did show a weak, statistically significant, increase after substorm onsets. CEPs had no significant association with subsequent storm or substorm onsets. We conclude that substorm acceleration may contribute to CEPs but CEPs are unlikely to contribute to global magnetospheric dynamics.

scholarly journals Storm-time ionization enhancements at the topside low-latitude ionosphere

2008 ◽  
Vol 26 (4) ◽  
pp. 867-876 ◽  
Author(s):  
A. Dmitriev ◽  
H.-C. Yeh
Keyword(s):  
Radiation Belt ◽  
Temporal Dynamics ◽  
Geomagnetic Storms ◽  
Energetic Particles ◽  
Low Latitude ◽  
Ion Density ◽  
Low Latitude Ionosphere ◽  
Using Data ◽  
Mev Protons ◽  
Earth Radiation

Abstract. Ion density enhancements at the topside low-latitude ionosphere during a Bastille storm on 15–16 July 2000 and Halloween storms on 29–31 October 2003 were studied using data from ROCSAT-1/IPEI experiment. Prominent ion density enhancements demonstrate similar temporal dynamics both in the sunlit and in the nightside hemispheres. The ion density increases dramatically (up to two orders of magnitude) during the main phase of the geomagnetic storms and reaches peak values at the storm maximum. The density enhancements are mostly localized in the region of a South Atlantic Anomaly (SAA), which is characterized by very intense fluxes of energetic particles. The dynamics of near-Earth radiation was studied using SAMPEX/LEICA data on >0.6 MeV electrons and >0.8 MeV protons at around 600 km altitude. During the magnetic storms the energetic particle fluxes in the SAA region and in its vicinity increase more than three orders of magnitude. The location of increased fluxes overlaps well with the regions of ion density enhancements. Two mechanisms were considered to be responsible for the generation of storm-time ion density enhancements: prompt penetration of the interplanetary electric field and abundant ionization of the ionosphere by enhanced precipitation of energetic particles from the radiation belt.

scholarly journals Strong southward and northward currents observed in the inner plasma sheet

2019 ◽  
Vol 37 (5) ◽  
pp. 931-941
Author(s):  
Yan-Yan Yang ◽  
Chao Shen ◽  
Yong Ji
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
Geomagnetic Storms ◽  
Energetic Particles ◽  
Inner Magnetosphere ◽  
Function Analyzer ◽  
Cluster Ion ◽  
Energetic Particle Flux ◽  
Field Lines ◽  
The Magnetic Field

Abstract. It is generally believed that field-aligned currents (FACs) and the ring current (RC) are two dominant parts of the inner magnetosphere. However, using the Cluster spacecraft crossing the pre-midnight inner plasma sheet in the latitudinal region between 10 and 30∘ N, it is found that, during intense geomagnetic storms, in addition to FACs and the RC, strong southward and northward currents also exist which should not be FACs because the magnetic field in these regions is mainly along the x–y plane. Detailed investigation shows that both magnetic-field lines (MFLs) and currents in these regions are highly dynamic. When the curvature of MFLs changes direction in the x–y plane, the current also alternatively switches between being southward and northward. To investigate the generation mechanism of the southward and northward current, we employed the analysis of energetic particle flux up to 1 MeV. For energetic particles below 40 keV, observations from Cluster CIS/CODIF (Cluster Ion Spectrometry COmposition and DIstribution Function analyzer) are used. However, for higher-energy particles, the flux is obtained by extrapolations of low-energy particle data through Kappa distribution. The result indicates that the most reasonable cause of these southward and northward currents is the curvature drift of energetic particles.

Comparison of External ULF wave Sources in Driving Radiation Belt Electron Dynamics

2021 ◽  
Author(s):  
Zhe Niu ◽  
Alexander Degeling ◽  
Quanqi Shi
Keyword(s):  
Radiation Belt ◽  
Geomagnetic Storms ◽  
Dynamic Pressure ◽  
Wave Model ◽  
Energetic Particles ◽  
Generation Mechanism ◽  
Mhd Waves ◽  
Ulf Waves ◽  
Wave Source ◽  
Ulf Wave

<p>For the study of Earth's radiation belts, an outstanding problem is the identification and prediction of dynamic variations of Earth's trapped energetic particles, in particular during geomagnetic storms. Statistical studies indicate that different types of geomagnetic storms (e.g. CIR and CME driven storms) have differing efficiencies in their ability to cause energization, transport and loss of energetic particles. This is most likely due to differences in the dominant mechanisms by which particles are affected between the storm types, and the locations within the magnetosphere where these mechanisms operate. For example, the dominant external generation mechanism for Pc5 ULF waves during CME driven storms may be magnetopause buffeting across the dayside, while for CIR driven storms the Kelvin-Helmholtz Instability (KHI) along the morning and evening flanks is more likely dominant. This changes the location and efficiency by which ULF waves can resonantly interact with radiation belt particles in these two storm types.</p><p>In this study, we use a 2D MHD wave model to investigate how the dominant generation mechanism in the case of CIR and CME driven storms determines the ability for externally generated wave power to penetrate deeply into the magnetosphere. In order to do this, we model ideal MHD waves in a 2D box model magnetosphere with a parabolic magnetopause boundary layer. We consider how fluctuations in dynamic pressure generate magnetopause buffeting perturbations that launch MHD fast mode waves, following the approach of Degeling et al., JGR 2011. We also include in our simulation a simple model for magnetosheath flow, and calculate the local linear KHI growth rate for perturbations along the magnetopause flanks as a function of frequency to provide a KHI driven wave source.</p>

scholarly journals Relationship between solar activity and Δ14C peaks in AD 775, AD 994, and 660 BC

Radiocarbon ◽  
2017 ◽  
Vol 59 (4) ◽  
pp. 1147-1156 ◽  
Author(s):  
Junghun Park ◽  
John Southon ◽  
Simon Fahrni ◽  
Pearce Paul Creasman ◽  
Richard Mewaldt
Keyword(s):  
Solar Activity ◽  
Geomagnetic Storms ◽  
Solar Energetic Particle ◽  
Peak Height ◽  
Energetic Particles ◽  
Solar Energetic Particles ◽  
High Solar Activity ◽  
Published Data ◽  
Enhanced Production ◽  
Mass Ejection

ABSTRACTSince the AD 775 and AD 994 Δ14C peak (henceforth M12) was first measured by Miyake et al. (2012, 2013), several possible production mechanisms for these spike have been suggested, but the work of Mekhaldi et al. (2015) shows that a very soft energy spectrum was involved, implying that a strong solar energetic particle (SEP) event (or series of events) was responsible. Here we present Δ14C values from AD 721–820 Sequoiadendron giganteum annual tree-ring samples from Sequoia National Park in California, USA, together with Δ14C in German oak from 650–670 BC. The AD 721–820 measurements confirm that a sharp Δ14C peak exists at AD 775, with a peak height of approximately 15‰ and show that this spike was preceded by several decades of rapidly decreasing Δ14C. A sharp peak is also present at 660 BC, with a peak height of about 10‰, and published data (Reimer et al. 2013) indicate that it too was preceded by a multi-decadal Δ14C decrease, suggesting that solar activity was very strong just prior to both Δ14C peaks and may be causally related. During periods of strong solar activity there is increased probability for coronal mass ejection (CME) events that can subject the Earth’s atmosphere to high fluencies of solar energetic particles (SEPs). Periods of high solar activity (such as one in October–November 2003) can also often include many large, fast CMEs increasing the probability of geomagnetic storms. In this paper we suggest that the combination of large SEP events and elevated geomagnetic activity can lead to enhanced production of 14C and other cosmogenic isotopes by increasing the area of the atmosphere that is irradiated by high solar energetic particles.

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