Energetic electron enhancements under the radiation belt (<i>L</i> < 1.2) during a non-storm interval on 1 August 2008

Abstract

<jats:p>Abstract. An unusual event of deep injections of &gt;30 keV electrons from the radiation belt to low L shells (L&lt;1.2) in the midnight–dawn sector was found from NOAA/POES observations during quiet geomagnetic conditions on 1 August 2008. Using THEMIS observations in front of the bow shock, we found transient foreshock conditions and interplanetary magnetic field (IMF) discontinuities passing the subsolar region at that time. These conditions resulted in generation of plasma pressure pulses and fast plasma jets observed by THEMIS, respectively, in the foreshock and magnetosheath. Signatures of interactions of pressure pulses and jets with the magnetopause were found in THEMIS and GOES measurements in the dayside magnetosphere and ground magnetogram records from INTERMAGNET. The jets produce penetration of hot magnetosheath plasma into the dayside magnetosphere, as was observed by the THEMIS probes after approaching the magnetopause. High-latitude precipitations of the hot plasma were observed by NOAA/POES satellites on the dayside. The precipitations preceded the &gt;30 keV electron injections at low latitudes. We propose a scenario of possible association between the phenomena observed. However, the scenario cannot be firmly supported because of the lack of experimental data on electric fields at the heights of electron injections. This should be a subject of future experiments. </jats:p>

Solar-Cycle Variations of Forbidden Energetic Electrons Enhancements

“…However, which electrodynamic process leads to the appearance of sufficiently strong (several mV/m) convection electric field at heights less than 2000 km is still an open question. Additionally, note an interesting fact that many FEE events observed in the absence of geomagnetic storms often occurred during the solar minimum [27]. The authors found that the trigger for such events is local pressure pulses associated with the dynamics of the foreshock in front of the Earth's bow shock.…”

Quiet Time Structured Pc1 Waves Generated During Transient Foreshock

“…It is known that sometimes the upstream solar wind and IMF can differ from those near the front of the Earth's bow shock, especially it concerns the magnetic field direction along the solar wind flow (radial IMF; e.g., Bier et al, ; Suvorova & Dmitriev, ; Vokhmyanin et al, ; Zastenker et al, ). The near‐Earth THEMIS observations provide reliable information on solar wind and IMF parameters directly affecting the magnetosphere (Suvorova, et al, ).…”