Turner D. L., V. Angelopoulos, Y. Shprits, A. Kellerman, P. Cruce, D. Larson, (2012), Radial distributions of equatorial phase space density for outer radiation belt electrons, Geophysical Research Letters, 39, doi:10.1029/2012GL051722
Abstract
We present the first direct observations of equatorial electron phase space density (PSD) as a function of the three adiabatic invariants throughout the outer radiation belt using data from the Solid State Telescopes on THEMIS-D. We estimate errors in PSD that result from data fitting and uncertainty in the calculation of the second and third invariants based on performance-weighted results from seven different magnetic field models. The PSD gradients beyond geosynchronous orbit (GEO) are energy dependent, revealing different source regions for the relativistic and non-relativistic populations. Specifically, the PSD distribution of outer belt relativistic electrons is peaked near L* ≈ 5.5. These features are typical for the outer belt, based on a survey of a two-month period from 01 Feb.–31 Mar. 2010. The results are consistent with previous studies, which were based on off-equatorial observations, but remove the high uncertainties introduced from mapping by using truly equatorial measurements (i.e., within only a few degrees of the magnetic equator) and quantifying the error in PSD. The newly calibrated THEMIS-SST dataset forms a powerful tool for exploration of the near-Earth magnetosphere, especially when combined with the upcoming RBSP mission.Authors (sorted by name)
Angelopoulos Cruce Kellerman Shprits TurnerJournal / Conference
Geophysical Research LettersAcknowledgments
We would like to thank the THEMIS mission and instrument teams; Victor Kai for assistance with Geant4 simulations; Janet Green for useful discussions on estimating error in PSD; the Geant4 (http://geant4.cern.ch/) development team; and the development teams for the IRBEM library (http://craterre.onecert.fr/prbem/irbem/description.html) and SpacePy tools (http://spacepy.lanl.gov/). This work was funded under NASA contract NAS5‐02099.Grants
NAS5‐02099Bibtex
@article{doi:10.1029/2012GL051722,
author = {Turner, D. L. and Angelopoulos, V. and Shprits, Y. and Kellerman, A. and Cruce, P. and Larson, D.},
title = {Radial distributions of equatorial phase space density for outer radiation belt electrons},
journal = {Geophysical Research Letters},
volume = {39},
number = {9},
year ={2012},
pages = {},
keywords = {particle acceleration, phase space density, radiation belts},
doi = {10.1029/2012GL051722},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2012GL051722},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2012GL051722},
abstract = {We present the first direct observations of equatorial electron phase space density (PSD) as a function of the three adiabatic invariants throughout the outer radiation belt using data from the Solid State Telescopes on THEMIS-D. We estimate errors in PSD that result from data fitting and uncertainty in the calculation of the second and third invariants based on performance-weighted results from seven different magnetic field models. The PSD gradients beyond geosynchronous orbit (GEO) are energy dependent, revealing different source regions for the relativistic and non-relativistic populations. Specifically, the PSD distribution of outer belt relativistic electrons is peaked near L* ≈ 5.5. These features are typical for the outer belt, based on a survey of a two-month period from 01 Feb.–31 Mar. 2010. The results are consistent with previous studies, which were based on off-equatorial observations, but remove the high uncertainties introduced from mapping by using truly equatorial measurements (i.e., within only a few degrees of the magnetic equator) and quantifying the error in PSD. The newly calibrated THEMIS-SST dataset forms a powerful tool for exploration of the near-Earth magnetosphere, especially when combined with the upcoming RBSP mission.}
}