The Global Positioning System constellation as a space weather monitor: Comparison of electron measurements with Van Allen Probes data

TitleThe Global Positioning System constellation as a space weather monitor: Comparison of electron measurements with Van Allen Probes data
Publication TypeJournal Article
Year of Publication2016
AuthorsMorley, SK, Sullivan, JP, Henderson, MG, J. Blake, B, Baker, DN
JournalSpace Weather
Date Published02/2016
KeywordsGlobal Positioning System; Van Allen Probes
AbstractEnergetic electron observations in Earth's radiation belts are typically sparse and multi-point studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross-calibration into two parts – one that removes any spectral assumptions from the CXD flux calculation, and one that compares the energy spectra – we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra we use a combination of four distributions that, together, capture a wide range of observed spectral shapes. Our two-step approach allowed us to identify, and correct for, small systematic offsets between block IIR and IIF satellites. Using the Magnetic Electron Ion Spectrometer (MagEIS) and Relativistic Electron-Proton Telescope (REPT) on Van Allen Probes as a “gold standard” we demonstrate that the CXD instruments are well-understood. A robust statistical analysis shows that CXD and Van Allen Probes fluxes are similar and the measured fluxes from CXD are typically within a factor of 2 of Van Allen Probes at energies ≲4 MeV. We present data from 17 CXD-equipped GPS satellites covering the 2015 “St. Patrick's Day” geomagnetic storm to illustrate the scientific applications of such a high data density satellite constellation, and therefore demonstrate that the GPS constellation is positioned to enable new insights in inner magnetospheric physics and space weather forecasting.
URLhttp://doi.wiley.com/10.1002/2015SW001339
DOI10.1002/2015SW001339
Short TitleSpace Weather


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