scholarly journals The magnetic local time distribution of energetic electrons in the radiation belt region

2017 ◽  
Vol 122 (8) ◽  
pp. 8108-8123 ◽  
Author(s):  
Hayley J. Allison ◽  
Richard B. Horne ◽  
Sarah A. Glauert ◽  
Giulio Del Zanna
Keyword(s):  
Local Time ◽  
Time Distribution ◽  
Radiation Belt ◽  
Magnetic Local Time ◽  
Energetic Electrons

scholarly journals POLAR spacecraft observations of helium ion angular anisotropy in the Earth's radiation belts

1999 ◽  
Vol 17 (6) ◽  
pp. 723-733 ◽  
Author(s):  
W. N. Spjeldvik ◽  
T. A. Fritz ◽  
J. Chen ◽  
R. B. Sheldon
Keyword(s):  
Local Time ◽  
Pitch Angle ◽  
Radiation Belt ◽  
Radiation Belts ◽  
Magnetic Local Time ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
Helium Ion ◽  
Earth’S Radiation Belt ◽  
Earth's Radiation Belts

Abstract. New observations of energetic helium ion fluxes in the Earth's radiation belts have been obtained with the CAMMICE/HIT instrument on the ISTP/GGS POLAR spacecraft during the extended geomagnetically low activity period April through October 1996. POLAR executes a high inclination trajectory that crosses over both polar cap regions and passes over the geomagnetic equator in the heart of the radiation belts. The latter attribute makes possible direct observations of nearly the full equatorial helium ion pitch angle distributions in the heart of the Earth's radiation belt region. Additionally, the spacecraft often re-encounters the same geomagnetic flux tube at a substantially off-equatorial location within a few tens of minutes prior to or after the equatorial crossing. This makes both the equatorial pitch angle distribution and an expanded view of the local off-equatorial pitch angle distribution observable. The orbit of POLAR also permitted observations to be made in conjugate magnetic local time sectors over the course of the same day, and this afforded direct comparison of observations on diametrically opposite locations in the Earth's radiation belt region at closely spaced times. Results from four helium ion data channels covering ion kinetic energies from 520 to 8200 KeV show that the distributions display trapped particle characteristics with angular flux peaks for equatorially mirroring particles as one might reasonably expect. However, the helium ion pitch angle distributions generally flattened out for equatorial pitch angles below about 45°. Significant and systematic helium ion anisotropy difference at conjugate magnetic local time were also observed, and we report quiet time azimuthal variations of the anisotropy index.Key words. Magnetospheric physics (energetic particles · trapped; magnetospheric configuration and dynamics; plasmasphere)

scholarly journals Magnetic local time dependency of radiation belt electron precipitation: impact on polar ozone

2020 ◽  
Author(s):  
Pekka T. Verronen ◽  
Daniel R. Marsh ◽  
Monika E. Szeląg ◽  
Niilo Kalakoski
Keyword(s):  
Local Time ◽  
Radiation Belt ◽  
Climate Model ◽  
Energetic Electron ◽  
Coupled Model ◽  
Magnetic Local Time ◽  
Polar Regions ◽  
Research Activity ◽  
Diurnal Variability ◽  
Polar Ozone

Abstract. The radiation belts are regions in the near-Earth space where solar wind electrons are captured by the Earth's magnetic field. A portion of these electrons is continuously lost into the atmosphere where they cause ionisation and chemical changes. Driven by solar activity, electron forcing leads to ozone variability in the polar regions. Understanding possible dynamical connections to regional climate is an on-going research activity which supports the assessment of greenhouse gas driven climate change by better definition of the solar-driven variability. In the context of the Coupled Model Intercomparison Project Phase 6 (CMIP6), energetic electron and proton precipitation is included in the solar forcing recommendation for the first time. For radiation belt electrons, CMIP6 forcing is from a daily, zonal mean proxy model. This zonal mean model ignores the well-known dependency of precipitation on magnetic local time (MLT), i.e. its diurnal variability. Here we use the Whole Atmosphere Community Climate Model with lower ionospheric chemistry extension (WACCM-D) to study the effect of MLT dependency of electron forcing on the polar ozone response. We analyse simulations applying MLT-dependent and MLT-independent forcings, and contrast ozone responses in monthly mean data as well as in monthly means of individual local time sectors. We consider two cases: 1) year 2003 and 2) extreme, long-duration forcing. Our results indicate that the ozone responses to MLT-dependent and MLT-independent forcings are very similar, and the differences found are small compared to those related to overall uncertainties in electron forcing. We conclude that electron forcing that ignores the MLT dependency will still provide an accurate ozone response in long-term climate simulations.

scholarly journals Magnetic Local Time‐Resolved Examination of Radiation Belt Dynamics during High‐Speed Solar Wind Speed‐Triggered Substorm Clusters

2019 ◽  
Vol 46 (17-18) ◽  
pp. 10219-10229 ◽  
Author(s):  
Craig J. Rodger ◽  
Drew L. Turner ◽  
Mark A. Clilverd ◽  
Aaron T. Hendry
Keyword(s):  
Solar Wind ◽  
Wind Speed ◽  
Local Time ◽  
High Speed ◽  
Radiation Belt ◽  
Solar Wind Speed ◽  
Magnetic Local Time ◽  
Time Resolved ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

Local time and seasonal variations in the precipitation of energetic electrons from the inner radiation belt by cyclotron resonance with waves from powerful VLF transmitters

Radio Science ◽  
1995 ◽  
Vol 30 (1) ◽  
pp. 47-55 ◽  
Author(s):  
Dayton W. Datlowe ◽  
William L. Imhof ◽  
Gerald J. Fishman ◽  
Mark H. Finger
Keyword(s):  
Local Time ◽  
Seasonal Variations ◽  
Cyclotron Resonance ◽  
Radiation Belt ◽  
Energetic Electrons

scholarly journals Magnetic-local-time dependency of radiation belt electron precipitation: impact on ozone in the polar middle atmosphere

2021 ◽  
Author(s):  
Pekka T. Verronen ◽  
Daniel R. Marsh ◽  
Monika E. Szeląg ◽  
Niilo Kalakoski
Keyword(s):  
Local Time ◽  
Radiation Belt ◽  
Climate Model ◽  
Middle Atmosphere ◽  
Energetic Electron ◽  
Magnetic Local Time ◽  
Local Times ◽  
Ongoing Research ◽  
Diurnal Variability ◽  
Climate Simulations

<div> <div> <div> <p>The radiation belts are regions in the near-Earth space where solar wind electrons are captured by the Earth’s magnetic field. A portion of these electrons is continuously lost into the atmosphere where they cause ionization and chemical changes. Driven by the solar activity, the electron forcing leads to ozone variability in the polar stratosphere and mesosphere. Understanding the possible dynamical connections to regional climate is an ongoing research activity which supports the assessment of greenhouse-gas-driven climate change by a better definition of the solar-driven variability. In the context of the Coupled Model Intercomparison Project Phase 6 (CMIP6), energetic electron and proton precipitation is included in the solar-forcing recommendation for the first time. For the radiation belt electrons, the CMIP6 forcing is from a daily zonal-mean proxy model. This zonal-mean model ignores the well-known dependency of precipitation on magnetic local time (MLT), i.e. its diurnal variability. Here we use the Whole Atmosphere Community Climate Model with its lower-ionospheric-chemistry extension (WACCM-D) to study effects of the MLT dependency of electron forcing on the polar-ozone response. We analyse simulations applying MLT-dependent and MLT-independent forcings and contrast the resulting ozone responses in monthly-mean data as well as in monthly means at individual local times. We consider two cases: (1) the year 2003 and (2) an extreme, continuous forcing. Our results indicate that the ozone responses to the MLT-dependent and the MLT-independent forcings are very similar, and the differences found are small compared to those caused by the overall uncertainties related to the representation of electron forcing in climate simulations. We conclude that the use of daily zonal-mean electron forcing will provide an accurate ozone response in long-term climate simulations.</p> </div> </div> </div>

The magnetic local time distribution of ring current during the geomagnetic storm

2013 ◽  
Vol 78 ◽  
pp. 52-63 ◽  
Author(s):  
X.D. Zhao ◽  
A.M. Du ◽  
W.Y. Xu
Keyword(s):  
Geomagnetic Storm ◽  
Local Time ◽  
Time Distribution ◽  
Ring Current ◽  
Magnetic Local Time
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