Visualization of ion cyclotron wave and particle interactions in the inner magnetosphere via THEMIS‐ASI observations

[1] Interaction with EMIC (electromagnetic ion cyclotron) waves is thought to be a key component contributing to the very rapid loss of both ring current and radiation belt particles into the atmosphere. Estimated loss rates are heavily dependent on the assumed spatial distribution of the EMIC wave. Statistical maps of the spatial distribution have been produced using in-situ satellite data. However, with limited satellite data it is impossible to deduce the true spatial distribution. In this study, we present ground-based observations using all-sky imager and search coil magnetometer networks, which provide the large-scale distribution and motion of the EMIC wave-particle interaction regions. We observed several spots of isolated proton auroras simultaneously with Pc1/EMIC waves at subauroral latitudes during the expansion phase of a storm-time substorm on 9 March 2008. The isolated auroras were distributed over ∼4-hours MLT preceding midnight. The POES-17 satellite confirmed enhancements of 30-keV proton precipitations over the isolated auroras. The equatorward motion of the auroras and frequency drift of the wave were consistent with the plasmasphere eroding due to a polar cap potential enhancement modeled by a numerical simulation. We also found that relativistic electron precipitation was not always associated with the isolated aurora, depending strongly on the plasma density profile near the plasmapause. This study shows that the specific distribution of ring current proton precipitation can be visualized through the ground network observations. By combining with upcoming inner-magnetosphere satellite missions, these remote-sensing observations are very important for quantitative understanding of the particle loss in the inner magnetosphere.

[1]  J. Green,et al.  A Monte Carlo simulation of the NOAA POES Medium Energy Proton and Electron Detector instrument , 2011 .

[2]  J. Green,et al.  Use of POES SEM-2 observations to examine radiation belt dynamics and energetic electron precipitation into the atmosphere , 2010 .

[3]  M. Spasojević,et al.  Temporal evolution of proton precipitation associated with the plasmaspheric plume , 2009 .

[4]  J. Manninen,et al.  Proton aurora related to intervals of pulsations of diminishing periods , 2009 .

[5]  I. J. Rae,et al.  The Upgraded CARISMA Magnetometer Array in the THEMIS Era , 2008 .

[6]  K. Shiokawa,et al.  Precipitation of radiation belt electrons by EMIC waves, observed from ground and space , 2008 .

[7]  Harald U. Frey,et al.  The THEMIS Array of Ground-based Observatories for the Study of Auroral Substorms , 2008 .

[8]  K. Shiokawa,et al.  Simultaneous appearance of isolated auroral arcs and Pc 1 geomagnetic pulsations at subauroral latitudes , 2008 .

[9]  V. Jordanova,et al.  Relativistic electron precipitation by EMIC waves from self‐consistent global simulations , 2008 .

[10]  H. Frey,et al.  Subauroral proton spots visualize the Pc1 source , 2007 .

[11]  M. Spasojević,et al.  Modeling the electromagnetic ion cyclotron wave‐induced formation of detached subauroral proton arcs , 2007 .

[12]  K. Shiokawa,et al.  Simultaneous ground and satellite observations of an isolated proton arc at subauroral latitudes , 2006 .

[13]  Martin Connors,et al.  The THEMIS all-sky imaging array—system design and initial results from the prototype imager , 2006 .

[14]  G. Haerendel,et al.  Subauroral morning proton spots (SAMPS) as a result of plasmapause‐ring‐current interaction , 2004 .

[15]  Umran S. Inan,et al.  The link between a detached subauroral proton arc and a plasmaspheric plume , 2004 .

[16]  J. Albert.  Evaluation of quasi-linear diffusion coefficients for EMIC waves in a multispecies plasma , 2003 .

[17]  Richard M. Thorne,et al.  Relativistic electron pitch-angle scattering by electromagnetic ion cyclotron waves during geomagnetic storms , 2003 .

[18]  P. Anderson,et al.  Interplanetary magnetic field control of afternoon-sector detached proton auroral arcs , 2002 .

[19]  J. Gérard,et al.  Precipitation of auroral protons in detached arcs , 2002 .

[20]  A. Nagy,et al.  High‐altitude energy source(s) for stable auroral red arcs , 1997 .

[21]  H. Hayakawa,et al.  Cross polar cap diameter and voltage as a function of PC index and interplanetary quantities , 1996 .

[22]  D. Stern.  A study of the electric field in an open magnetospheric model , 1973 .

[23]  C. Kennel,et al.  Relativistic electron precipitation during magnetic storm main phase , 1971 .

[24]  J. Cornwall,et al.  TURBULENT LOSS OF RING-CURRENT PROTONS. , 1970 .

[25]  A. Kumamoto,et al.  Jovian slow‐drift shadow events , 2010 .

[26]  C. E. Rasmussen,et al.  A two-dimensional model of the plasmasphere : refilling time constants , 1993 .

[27]  H. Volland.  A semiempirical model of large‐scale magnetospheric electric fields , 1973 .

[28]  R. Eather.  Spectral intensity ratios in proton‐induced auroras , 1968 .