Pitch Angle Dependence of Energetic Electron Precipitation: Energy Deposition, Backscatter, and the Bounce Loss Cone

2018 ◽  
Author(s):  
R. A. Marshall ◽  
J. Bortnik
Keyword(s):  
Pitch Angle ◽  
Energy Deposition ◽  
Energetic Electron ◽  
Electron Precipitation ◽  
Loss Cone ◽  
Angle Dependence

scholarly journals Comparison between CNA and energetic electron precipitation: simultaneous observation by Poker Flat Imaging Riometer and NOAA satellite

2005 ◽  
Vol 23 (5) ◽  
pp. 1555-1563 ◽  
Author(s):  
Y.-M. Tanaka ◽  
M. Ishii ◽  
Y. Murayama ◽  
M. Kubota ◽  
H. Mori ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Electron Flux ◽  
Energetic Electron ◽  
Energetic Particles ◽  
Electron Precipitation ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Loss Cone ◽  
Isotropic Pitch ◽  
Trapped Electron

Abstract. The cosmic noise absorption (CNA) is compared with the precipitating electron flux for 19 events observed in the morning sector, using the high-resolution data obtained during the conjugate observations with the imaging riometer at Poker Flat Research Range (PFRR; 65.11° N, 147.42° W), Alaska, and the low-altitude satellite, NOAA 12. We estimate the CNA, using the precipitating electron flux measured by NOAA 12, based on a theoretical model assuming an isotropic pitch angle distribution, and quantitatively compare them with the observed CNA. Focusing on the eight events with a range of variation larger than 0.4dB, three events show high correlation between the observed and estimated CNA (correlation coefficient (r0)>0.7) and five events show low correlation (r0<0.5). The estimated CNA is often smaller than the observed CNA (72% of all data for 19 events), which appears to be the main reason for the low-correlation events. We examine the assumption of isotropic pitch angle distribution by using the trapped electron flux measured at 80° zenith angle. It is shown that the CNA estimated from the trapped electron flux, assuming an isotropic pitch angle distribution, is highly correlated with the observed CNA and is often overestimated (87% of all data). The underestimate (overestimate) of CNA derived from the precipitating (trapped) electron flux can be interpreted in terms of the anisotropic pitch angle distribution similar to the loss cone distribution. These results indicate that the CNA observed with the riometer may be quantitatively explained with a model based on energetic electron precipitation, provided that the pitch angle distribution and the loss cone angle of the electrons are taken into account. Keywords. Energetic particles, precipitating – Energetic particles, trapped – Ionosphere-magnetosphere interactions

Statistical Distribution of Energetic Electron Precipitation due to Hiss Waves In the Earth’s Inner Magnetosphere

2021 ◽  
Author(s):  
Qianli Ma
Keyword(s):  
Energy Flux ◽  
Pitch Angle ◽  
Energetic Electron ◽  
Statistical Distribution ◽  
Electron Precipitation ◽  
Characteristic Energy ◽  
Loss Cone ◽  
Inner Magnetosphere ◽  
The Earth ◽  
Chorus Waves

&lt;p&gt;We investigate the statistical distribution of energetic electron precipitation from the equatorial magnetosphere due to hiss waves in the plasmasphere and plumes. Using Van Allen Probes measurements, we calculate the pitch angle diffusion coefficients at the pitch angle of bounce loss cone, and evaluate the energy spectrum of precipitating electron flux using quasi-linear theory. Our ~6.5 years survey shows that, during disturbed times, the plasmaspheric hiss mostly causes the electron precipitation at L &gt; 3 near the dayside in the plasmasphere, and hiss waves in plume cause the precipitation at L &gt; 5 near dayside and L &gt; 3.5 near the dusk side. The precipitating energy flux increases with increasing geomagnetic index, and is typically higher in the plasmaspheric plume than the plasmasphere. The characteristic energy of precipitation increases from ~20 keV at L = 6 to ~100 keV at L = 3, potentially causing the loss of electrons at several hundred keV. Although the total precipitating energy flux due to hiss waves is generally lower than the precipitation due to whistler mode chorus waves, the characteristic energy of precipitation due to hiss is higher, and the precipitation extends closer to the Earth.&lt;/p&gt;

Solar wind structures and their effects on energetic electron precipitation

2021 ◽  
Author(s):  
Josephine Alessandra Salice ◽  
Hilde Nesse Tyssøy ◽  
Christine Smith-Johnsen ◽  
Eldho Midhun Babu
Keyword(s):  
Solar Wind ◽  
Ozone Concentration ◽  
High Speed ◽  
Climate Models ◽  
Middle Atmosphere ◽  
Energetic Electron ◽  
Accurate Estimate ◽  
Electron Precipitation ◽  
Loss Cone ◽  
Speed Solar Wind

&lt;p&gt;Energetic electron precipitation (EEP) into the Earth's atmosphere can collide with gases and deposit their energy there. The collisions between electrons and atmospheric gasses initiate several chemical reactions which can reduce the ozone concentration. Ozone is critically important in the middle atmosphere energy budget as changes in the ozone concentration impact temperature and winds. EEP is not fully understood in terms of how much energy is being deposited and what the associated drivers are. An accurate quantification of EEP has limitations due to instrumental challenges and therefore imposes limitations of the associated EEP parameterization into climate models. A solution to this problem is a better understanding of the driver processes of energetic electron acceleration and precipitation, alongside optimized data handling. In this study the bounce loss cone fluxes are inferred from EEP measurements by the Medium Energy Proton and Electron Detector (MEPED) on board the Polar Orbiting Environmental Satellite (POES) and the Meteorological Operational Satellite Program of Europe (METOP) at tens of keV to relativistic energies. It investigates EEP in contexts of different solar wind structures: high-speed solar wind streams (HSSs) and coronal mass ejections (CMEs), during an eleven-year period from 2004 &amp;#8211; 2014. While today's chemistry climate models only provide snapshots of EEP, independent of context, this study aims to understand the context EEP is created in, which will allow a more accurate estimate of the EEP to be applied in atmospheric climate models.&lt;/p&gt;

scholarly journals Low altitude energetic electron lifetimes after enhanced magnetic activity as deduced from SAC-C and DEMETER data

2010 ◽  
Vol 28 (3) ◽  
pp. 849-859 ◽  
Author(s):  
S. Benck ◽  
L. Mazzino ◽  
M. Cyamukungu ◽  
J. Cabrera ◽  
V. Pierrard
Keyword(s):  
Pitch Angle ◽  
Energetic Electron ◽  
Magnetic Activity ◽  
Decay Rates ◽  
Data Sets ◽  
Quiet Time ◽  
Loss Cone ◽  
Energetic Electrons ◽  
Low Altitude ◽  
The Difference

Abstract. When flux enhancements of energetic electrons are produced as a consequence of geomagnetic storm occurrence, they tend to vanish gradually when the magnetic activity calms down and the fluxes decay to quiet-time levels. We use SAC-C and DEMETER low altitude observations to estimate the energetic electron lifetimes (E=0.16–1.4 MeV, L=1.6–5, B=0.22–0.46 G) and compare the decay rates to those observed at high altitude. While crossing the radiation belts at high latitude, the SAC-C and DEMETER instruments sample particles with small equatorial pitch angles (αeq<18° for L>2.5) whereas the comparison is done with other satellite data measured mainly in the equatorial plane (for αeq>75°). While in the inner belt and in the slot region no significant lifetime differences are observed from the data sets with different αeq, in the outer belt, for the least energetic electrons (<500 keV), the lifetimes are up to ~3 times larger for the electrons with the equatorial pitch-angle close to the loss cone than for those mirroring near the equator. The difference decreases with increasing energy and vanishes for energies of about 1 MeV.

scholarly journals Energetic electron precipitation into the middle atmosphere-Constructing the loss cone fluxes from MEPED POES

2016 ◽  
Vol 121 (6) ◽  
pp. 5693-5707 ◽  
Author(s):  
H. Nesse Tyssøy ◽  
M. I. Sandanger ◽  
L.-K. G. Ødegaard ◽  
J. Stadsnes ◽  
A. Aasnes ◽  
...  
Keyword(s):  
Middle Atmosphere ◽  
Energetic Electron ◽  
Electron Precipitation ◽  
Loss Cone

Statistical Study of Pitch Angle Diffusion during Substorm Injections

2020 ◽  
Author(s):  
Reihaneh Ghaffari ◽  
Christopher Cully
Keyword(s):  
Pitch Angle ◽  
Energetic Electron ◽  
Loss Cone ◽  
Linear Diffusion ◽  
Whistler Mode ◽  
Wave Measurements ◽  
Whistler Mode Waves ◽  
Substorm Injection ◽  
Injection Region

&lt;p&gt;Energetic Electron Precipitation (EEP) associated with substorm injections typically occurs when magnetospheric waves, particularly whistler-mode waves, resonantly interact with electrons to affect their equatorial pitch angle. This can be considered as a diffusion process that scatters particles into the loss cone. In this study, we investigate whistler-mode wave generation in conjunction with electron injections using in-situ wave measurements by the Themis mission. We calculate the pitch angle diffusion coefficient exerted by the observed wave activity using the quasi-linear diffusion approximation and estimate scattering efficiency in the substorm injection region to constrain where and how much scattering happens typically during these events.&lt;/p&gt;

The link between solar wind structures, geomagnetic indices, and energetic electron precipitation

2020 ◽  
Author(s):  
Josephine Salice ◽  
Hilde Nesse Tyssøy ◽  
Christine Smith-Johansen ◽  
Eldho Midhun Babu
Keyword(s):  
Solar Wind ◽  
Ozone Concentration ◽  
High Speed ◽  
Climate Models ◽  
Middle Atmosphere ◽  
Energetic Electron ◽  
Accurate Estimate ◽  
Electron Precipitation ◽  
Loss Cone ◽  
Accurate Quantification

&lt;p&gt;Energetic electron precipitation (EEP) into the Earth&amp;#8217;s atmosphere can collide with gases and deposit their energy there. The collisions between electrons and atmospheric gasses initiate several chemical reactions which can reduce the ozone concentration. Ozone is critically important in the middle atmosphere energy budget as changes in the ozone concentration impact temperature and winds. EEP is not fully understood in terms of how much energy is being deposited and what the associated drivers are.&amp;#160; An accurate quantification of EEP has limitations due to instrumental challenges and therefore imposes limitations of the associated EEP parameterization into climate models. A solution to this problem is a better understanding of the driver processes of energetic electron acceleration and precipitation, alongside optimized measurements. In this study the bounce loss cone fluxes are inferred from EEP measurements by MEPED on board NOAA/POES and EUMETSAT/METOP at tens of keV to relativistic energies. It investigates EEP in contexts of three different solar wind structures: high-speed streams, coronal mass ejections, and ambient or slow interstream solar wind, as well as geomagnetic activity. The study will focus on the year 2010 and aim to understand the context EEP is created in, which will allow a more accurate estimate of the EEP to be applied in atmospheric climate models&lt;/p&gt;

Energetic Electron Pitch Angle Distributions During the Cassini Final Orbits

2018 ◽  
Vol 45 (7) ◽  
pp. 2911-2917 ◽  
Author(s):  
J. F. Carbary ◽  
D. G. Mitchell ◽  
P. Kollmann ◽  
N. Krupp ◽  
E. Roussos ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Energetic Electron

scholarly journals Strong localized variations of the low-altitude energetic electron fluxes in the evening sector near the plasmapause

1998 ◽  
Vol 16 (1) ◽  
pp. 25-33 ◽  
Author(s):  
E. E. Titova ◽  
T. A. Yahnina ◽  
A. G. Yahnin ◽  
B. B. Gvozdevsky ◽  
A. A. Lyubchich ◽  
...  
Keyword(s):  
Sharp Increase ◽  
Electron Flux ◽  
Particle Interaction ◽  
Energetic Electron ◽  
Recovery Phase ◽  
Electron Precipitation ◽  
Statistical Characteristics ◽  
Evening Sector ◽  
Proton Precipitation ◽  
Low Altitude

Abstract. Specific type of energetic electron precipitation accompanied by a sharp increase in trapped energetic electron flux are found in the data obtained from low-altitude NOAA satellites. These strongly localized variations of the trapped and precipitated energetic electron flux have been observed in the evening sector near the plasmapause during recovery phase of magnetic storms. Statistical characteristics of these structures as well as the results of comparison with proton precipitation are described. We demonstrate the spatial coincidence of localized electron precipitation with cold plasma gradient and whistler wave intensification measured on board the DE-1 and Aureol-3 satellites. A simultaneous localized sharp increase in both trapped and precipitating electron flux could be a result of significant pitch-angle isotropization of drifting electrons due to their interaction via cyclotron instability with the region of sharp increase in background plasma density.Key words. Ionosphere (particle precipitation; wave-particle interaction) Magnetospheric Physics (plasmasphere)

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