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Radial distributions of equatorial phase space density for outer radiation belt electrons
Author(s) -
Turner D. L.,
Angelopoulos V.,
Shprits Y.,
Kellerman A.,
Cruce P.,
Larson D.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl051722
Subject(s) - van allen radiation belt , physics , van allen probes , magnetosphere , equator , geosynchronous orbit , geophysics , electron , phase space , computational physics , electron density , phase (matter) , magnetic field , astrophysics , satellite , astronomy , latitude , quantum mechanics , thermodynamics
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.