scholarly journals Spectra of high energy electron precipitation and atmospheric ionization rates retrieval from balloon measurements

2019 ◽  
Vol 693 ◽  
pp. 133242 ◽  
Author(s):  
Irina Mironova ◽  
Galina Bazilevskaya ◽  
Gennady Kovaltsov ◽  
Anton Artamonov ◽  
Eugene Rozanov ◽  
...  
Keyword(s):  
High Energy ◽  
Energy Electron ◽  
Electron Precipitation ◽  
High Energy Electron ◽  
Atmospheric Ionization ◽  
Balloon Measurements ◽  
Ionization Rates

scholarly journals Pc5 modulation of high energy electron precipitation: particle interaction regions and scattering efficiency

2005 ◽  
Vol 23 (5) ◽  
pp. 1533-1542 ◽  
Author(s):  
E. Spanswick ◽  
E. Donovan ◽  
G. Baker
Keyword(s):  
Field Line ◽  
Electron Flux ◽  
High Energy ◽  
Energy Electron ◽  
Electron Precipitation ◽  
Necessary Condition ◽  
High Energy Electron ◽  
Magnetic Pulsation ◽  
Field Line Resonances ◽  
Morning Sector

Abstract. Using the NORSTAR riometer and CANOPUS magnetometer arrays we have investigated the modulation of high energy electron precipitation by ULF waves in the Pc5 frequency band. We conducted two separate studies of Pc5 activity in the riometers. The first is an independent survey of three riometer stations in the Churchill line (one at each sub-auroral, auroral, and typical polar cap boundary latitudes) in which we identified all riometer Pc5-band pulsations over 11 years. All had a corresponding magnetometer pulsation implying that a magnetic pulsation, is a necessary condition for a riometer pulsation (in the Pc5 Band). We find seasonal and latitude dependencies in the occurrence of riometer pulsations. By a factor of two, there are more riometer pulsations occurring in the fall-winter than the spring-summer. At higher latitudes there is a tendency towards noon pulsations during the spring-summer, suggesting that the criteria for riometer pulsations is affected by the dipole tilt. Our second study was based on the previous magnetometer study of Baker et al. (2003). Using the database of Pc5 activity from that study we were able to select the riometer Pc5 pulsations which adhere to the strict Pc5 definition in the magnetometer. We find that roughly 95% of the riometer pulsations occurred in the morning sector compared to 70% in the magnetometer. Given a magnetometer pulsation at Gillam in the morning sector, there is a 70% chance of there being a corresponding riometer pulsation. The morning sector probabilities at Rankin (geomagnetic (PACE) latitude 74°) and Pinawa (61°) are 3% and 5%, respectively. These statistics suggest there is a localized region in the pre-noon magnetosphere where Pc5 band ULF activity can modulate high energy electron precipitation. We also find that riometer pulsations display a Kp selection towards mid (i.e. 3–4) activity levels which mimics the product of the Kp dependence of high-energy electron fluxes on the dawn side (from CRRES) and all magnetic Pc5 activity. A superposed epoch analysis revealed that the elevated electron flux needed to produce a riometer pulsation is most likely provided by substorm injections on the nightside. We also find that the amplitude of modulated precipitation correlates well with the product of the background absorption and the magnetic pulsation amplitude, again leading to the idea that a riometer pulsation needs both favorable magnetospheric electron flux conditions and large enough magnetic Pc5 wave activity. We further separate our pulsations into field line resonances (FLRs), and non-field line resonances (non-FLRs), as identified in the Baker et al. (2003) survey. We find that FLRs are more efficient at modulating particle precipitation, and non-FLRs display an amplitude cutoff below which they do not interact with the high energy electron population. We conclude that the high energy electron precipitation associated with Pc5 pulsations is caused by pitch angle scattering (diffusion) rather than parallel acceleration. We suggest two future studies that are natural extensions of this one. Keywords. Energetic Particles/Precipitating; Wave-Particle Interactions; Auroral Phenomena

Mesospheric ozone destruction by high-energy electron precipitation associated with pulsating aurora

2016 ◽  
Vol 121 (19) ◽  
pp. 11,852-11,861 ◽  
Author(s):  
Esa Turunen ◽  
Antti Kero ◽  
Pekka T. Verronen ◽  
Yoshizumi Miyoshi ◽  
Shin-Ichiro Oyama ◽  
...  
Keyword(s):  
High Energy ◽  
Energy Electron ◽  
Electron Precipitation ◽  
High Energy Electron ◽  
Ozone Destruction ◽  
Mesospheric Ozone

scholarly journals Simulated seasonal impact on middle atmospheric ozone from high-energy electron precipitation related to pulsating aurorae

2021 ◽  
Vol 39 (5) ◽  
pp. 883-897
Author(s):  
Pekka T. Verronen ◽  
Antti Kero ◽  
Noora Partamies ◽  
Monika E. Szeląg ◽  
Shin-Ichiro Oyama ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Energetic Electron ◽  
Solar Energetic Particle ◽  
High Energy ◽  
Energy Electron ◽  
Electron Precipitation ◽  
Research Station ◽  
High Energy Electron

Abstract. Recent simulation studies have provided evidence that a pulsating aurora (PsA) associated with high-energy electron precipitation is having a clear local impact on ozone chemistry in the polar middle mesosphere. However, it is not clear if the PsA is frequent enough to cause longer-term effects of measurable magnitude. There is also an open question of the relative contribution of PsA-related energetic electron precipitation (PsA EEP) to the total atmospheric forcing by solar energetic particle precipitation (EPP). Here we investigate the PsA-EEP impact on stratospheric and mesospheric odd hydrogen, odd nitrogen, and ozone concentrations. We make use of the Whole Atmosphere Community Climate Model and recent understanding on PsA frequency, latitudinal and magnetic local time extent, and energy-flux spectra. Analysing an 18-month time period covering all seasons, we particularly look at PsA-EEP impacts at two polar observation stations located at opposite hemispheres: Tromsø in the Northern Hemisphere (NH) and Halley Research Station in the Southern Hemisphere (SH). We find that PsA EEP can have a measurable impact on ozone concentration above 30 km altitude, with ozone depletion by up to 8 % seen in winter periods due to PsA-EEP-driven NOx enhancement. We also find that direct mesospheric NOx production by high-energy electrons (E> 100 keV) accounts for about half of the PsA-EEP-driven upper stratospheric ozone depletion. A larger PsA-EEP impact is seen in the SH where the background dynamical variability is weaker than in the NH. Clearly indicated from our results, consideration of polar vortex dynamics is required to understand PsA-EEP impacts seen at ground observation stations, especially in the NH. We conclude that PsA-EEP has the potential to make an important contribution to the total EPP forcing; thus, it should be considered in atmospheric and climate simulations.

scholarly journals Exceptional middle latitude electron precipitation detected by balloon observations: implications for atmospheric composition

2021 ◽  
Author(s):  
Irina Mironova ◽  
Miriam Sinnhuber ◽  
Galina Bazilevskaya ◽  
Mark Clilverd ◽  
Bernd Funke ◽  
...  
Keyword(s):  
Energetic Particle ◽  
Climate Model ◽  
High Energy ◽  
Energy Electron ◽  
Electron Precipitation ◽  
Atmospheric Composition ◽  
Precipitation Event ◽  
High Energy Electron ◽  
Particle Precipitation ◽  
Energetic Particle Precipitation

Abstract. Energetic particle precipitation leads to ionization in the Earth's atmosphere, initiating the formation of active chemical species which destroy ozone and have the potential to impact atmospheric composition and dynamics down to the troposphere. We report on one exceptionally strong high-energy electron precipitation event detected by balloon measurements in middle latitudes on 14 December 2009 with ionization rates locally comparable to strong solar proton events. This electron precipitation was likely caused by wave-particle interactions in the slot region between the inner and outer radiation belts, connected with still not well understood natural phenomena in the magnetosphere. Satellite observations of odd nitrogen and nitric acid are consistent with wide-spread electron precipitation into magnetic midlatitudes. Simulations with a 3D chemistry-climate model indicate almost complete destruction of ozone in the upper mesosphere over the region where high-energy electron precipitation occurred. Such an extraordinary type of energetic particle precipitation can have major implications for the atmosphere, and their frequency and strength should be carefully studied.

scholarly journals Enhanced EISCAT UHF backscatter during high-energy auroral electron precipitation

2013 ◽  
Vol 31 (10) ◽  
pp. 1681-1687 ◽  
Author(s):  
N. M. Schlatter ◽  
N. Ivchenko ◽  
T. Sergienko ◽  
B. Gustavsson ◽  
B. U. E. Brändström
Keyword(s):  
Electron Density ◽  
Doppler Shift ◽  
High Energy ◽  
Energy Electron ◽  
Electron Precipitation ◽  
High Latitudes ◽  
High Energy Electron ◽  
Incoherent Scatter ◽  
Auroral Electron ◽  
Incoherent Scatter Radars

Abstract. Natural enhancements in the backscattered power of incoherent scatter radars up to 5 orders of magnitudes above the thermal backscatter are sometimes observed at high latitudes. Recently observations of enhancements in the backscattered power including a feature at zero Doppler shift have been reported. These enhancements are limited in altitude to tens of kilometers. The zero Doppler shift feature has been interpreted as a signature of electron density cavitation. Enhanced plasma lines during these observations have also been reported. We report on the first EISCAT UHF observations of enhanced backscattered radar power including a zero Doppler shift feature. The enhancements originated from two distinct and intermittent layers at about 200 km altitude. The altitude extent of the enhancements, observed during auroral high-energy electron precipitation, was < 2 km.

Kinematic Approximations in TED and RHEED Analysis of Reconstructed Surfaces

1990 ◽  
Vol 48 (2) ◽  
pp. 396-397
Author(s):  
L. -M. Peng ◽  
M. J. Whelan
Keyword(s):  
Electron Diffraction ◽  
Kinematic Analysis ◽  
Incident Beam ◽  
High Energy ◽  
Energy Electron ◽  
Great Success ◽  
High Energy Electron ◽  
Kinematic Approximation ◽  
Reconstructed Surfaces

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.

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