Autor: |
Runov, A.1 (AUTHOR) arunov@igpp.ucla.edu, Angelopoulos, V.1 (AUTHOR), Weygand, J. M.1 (AUTHOR), Artemyev, A. V.1 (AUTHOR), Beyene, F.1 (AUTHOR), Sergeev, V.2 (AUTHOR), Kubyshkina, M.2 (AUTHOR), Henderson, M. G.3 (AUTHOR) |
Předmět: |
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Zdroj: |
Journal of Geophysical Research. Space Physics. Sep2022, Vol. 127 Issue 9, p1-17. 17p. |
Abstrakt: |
The main question addressed in this study is whether particles with relativistic energy can be injected directly into the inner magnetosphere by very near‐Earth reconnection during magnetic storms. We study a sequence of events observed in the solar wind, in the magnetotail, at geosynchronous orbit (GEO), in the inner magnetosphere, and in the ionosphere during the main phase of a geomagnetic storm on 16 June 2012–17 June 2012. The storm was caused by a magnetic cloud with a high dynamic pressure and a strong southward IMF lasting about 10 hr. These conditions caused an extreme compression of the magnetosphere (SymH reached ∼150 nT) and an enhancement of the lobe magnetic field strength to ∼90 nT at R ∼ 10 Earth radii (RE). We focus on an hour‐long interval between 1050 and 1150 UT on 17 June 2012 when the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites were at apogee at geocentric distances R ≈ 12 RE near midnight. At that time a thin current sheet formed between cis‐GEO distances and THEMIS. This thin current sheet reconnected between GEO and THEMIS. A strong lobe magnetic field enabled ion and electron energization to energies E ≈ 600 keV. Fluxes of high energy (up to relativistic) particles at GEO increased within ≈20 s after reconnection onset detected by THEMIS. Fluxes of relativistic electrons at L ∼ 4 in the morning sector increased within about 600 s after reconnection onset. We interpret these observations as signatures of direct injection of reconnected particles into the inner magnetosphere. Plain Language Summary: Solar flares, coronal mass ejection events may cause severe disturbances in the near‐Earth space environment called magnetic storms. During a magnetic storm the Earth magnetosphere experiences quite dramatic changes that include rapid reconfiguration of magnetic field lines that leads to conversion of the magnetic energy to kinetic and thermal energy of the space plasma (reconnection) and acceleration of charged particles. The accelerated particles and plasmas from the outer magnetosphere may penetrate deeper into the near‐Earth space, where the magnetic field is close to a dipole. Particles become trapped in the dipole field and form an electric current that flows around the Earth (ring current) and reduce the magnetic field observed on the ground. Details of the ring current formation are not well understood yet. In this paper we study a magnetic storm during which reconnection happened very close to the dipole field and particles, energized via reconnection were directly injected into the inner magnetosphere. Events like this are potentially hazardous for satellites on geosynchronous orbit and in the inner magnetosphere. Key Points: We studied space‐ and ground‐based observations during a storm caused by magnetic cloud impactOur observations suggest that a thin current sheet formed and reconnected at L about 10Reconnection caused relativistic particle injections into the inner magnetosphere [ABSTRACT FROM AUTHOR] |
Databáze: |
GreenFILE |
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