GPS TEC technique for observation of the evolution of substorm particle precipitation

[1] One of the signatures of magnetospheric substorms is the precipitation of high energy particles into the high latitude ionosphere. In this paper, we introduce a new method of tracking substorm particle precipitation using GPS Total Electron Content (TEC) and provide some preliminary observations of precipitation signatures from application of this method. Using TEC measurements from several GPS receivers, we examined particle precipitation signatures associated with two separate substorm events (4 October 2008 and 29 October 2008) and monitored the expansion of the high energy precipitation regions with a higher temporal and spatial resolution than previously available. For each event we have observed TEC signatures associated with substorm particle precipitation along 20 to 25 separate GPS raypaths from up to 7 GPS receivers located in the Canadian Arctic. This is in addition to particle injection signatures found in CLUSTER satellite data and precipitation signatures in ground based riometer data. Signature timing on different raypaths from different stations indicates a mainly northward (tailward) expansion of the precipitation (injection) region with a smaller westward (azimuthal) component for the events studied. By applying a triangulation method, we also calculated propagation velocity of the precipitation boundary in regions covered by our GPS receivers. For each substorm, expansion velocity ranged from 0.3–2 km/s northward and 0–1 km/s westward, and tended to decrease in magnitude at higher latitudes.

[1]  E. W. Hones,et al.  Multiple‐spacecraft and correlated riometer study of magnetospheric substorm phenomena , 1982 .

[2]  J. Hargreaves,et al.  Development of the auroral absorption substorm: Studies of pre-onset phase and sharp onset using an extensive riometer network , 1981 .

[3]  S. Wing,et al.  Magnetic dipolarization with substorm expansion onset , 2002 .

[4]  J. Hargreaves,et al.  Small-scale structure of ionospheric absorption of cosmic noise during pre-onset and sharp onset phases of an auroral absorption substorm , 1999 .

[5]  E. Spanswick,et al.  Azimuthal structures of substorm electron injection and their signatures in riometer observations , 2007 .

[6]  Richard B. Langley,et al.  Canadian High Arctic Ionospheric Network (CHAIN) , 2009 .

[7]  E. W. Hones,et al.  Near‐equatorial, high‐resolution measurements of electron precipitation at L ≃6.6 , 1981 .

[8]  F. Berkey,et al.  A synoptic investigation of particle precipitation dynamics for 60 substorms in IQSY (1964–1965) and IASY (1969) , 1974 .

[9]  Norbert Jakowski,et al.  Enhanced E-layer ionization in the auroral zones observed by radio occultation measurements onboard CHAMP and Formosat-3/COSMIC , 2007 .

[10]  B. Mauk,et al.  Plasma Injection During Substorms , 1987 .

[11]  M. Rees,et al.  Auroral ionization and excitation by incident energetic electrons , 1963 .

[12]  R. D. Belian,et al.  Numerical tracing of energetic particle drifts in a model magnetosphere , 1991 .

[13]  N. Tsyganenko.  A magnetospheric magnetic field model with a warped tail current sheet , 1989 .

[14]  P. Jayachandran,et al.  Azimuthal expansion of the dipolarization at geosynchronous orbits associated with substorms , 2009 .

[15]  K. Morzinski,et al.  Two-satellite observations of substorm injections at geosynchronous orbit , 2001 .

[16]  J. Hargreaves,et al.  Auroral radio absorption as an indicator of magnetospheric electrons and of conditions in the disturbed auroral D-region , 1984 .

[17]  J. Hargreaves.  Dynamics of auroral absorption in the midnight sector—The movement of absorption peaks in relation to the substorm onset , 1974 .

[18]  B. Arbesser-Rastburg,et al.  Measuring Ionospheric Scintillation in the Equatorial Region Over Africa, Including Measurements From SBAS Geostationary Satellite Signals , 2004 .

[19]  J. Hargreaves,et al.  Properties of spike events in auroral radio absorption , 1979 .

[20]  R. Hunsucker.  Chatanika radar investigation of high latitude E‐region ionization structure and dynamics , 1975 .

[21]  Michael Mendillo,et al.  Storms in the ionosphere: Patterns and processes for total electron content , 2006 .

[22]  T. J. Rosenberg,et al.  The local time, substorm, and seasonal dependence of electron precipitation at L=4 inferred from riometer measurements , 1986 .

[23]  C. Mcilwain.  Substorm Injection Boundaries , 1974 .

[24]  R. L. Arnoldy,et al.  PARTICLE SUBSTORMS OBSERVED AT THE GEOSTATIONARY ORBIT. , 1969 .

[25]  R. Langley,et al.  GPS total electron content variations associated with a polar cap arc , 2009 .

[26]  J. Liang,et al.  Remote‐sensing magnetospheric dynamics with riometers: Observation and theory , 2007 .

[27]  A. Weatherwax,et al.  Global observations of substorm injection region evolution: 27 August 2001 , 2009 .

[28]  A. Korth,et al.  Ground based identification of dispersionless electron injections , 2007 .

[29]  L. A. Hajkowicz.  The dynamics of a steep onset in the conjugate auroral riometer absorption , 1990 .

[30]  H. Yamagishi,et al.  Small-scale structure of electron density in the D region during onset phases of an auroral absorption substorm , 1997 .