Dataset Information

Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm.

ABSTRACT: During a magnetic storm on 23 June 2015, several very intense substorms took place, with signatures observed by multiple spacecraft including DMSP and Magnetospheric Multiscale (MMS). At the time of interest, DMSP F18 crossed inbound through a poleward expanding auroral bulge boundary at 23.5 h magnetic local time (MLT), while MMS was located duskward of 22 h MLT during an inward crossing of the expanding plasma sheet boundary. The two spacecraft observed a consistent set of signatures as they simultaneously crossed the reconnection separatrix layer during this very intense reconnection event. These include (1) energy dispersion of the energetic ions and electrons traveling earthward, accompanied with high electron energies in the vicinity of the separatrix; (2) energy dispersion of polar rain electrons, with a high-energy cutoff; and (3) intense inward convection of the magnetic field lines at the MMS location. The high temporal resolution measurements by MMS provide unprecedented observations of the outermost electron boundary layer. We discuss the relevance of the energy dispersion of the electrons, and their pitch angle distribution, to the spatial and temporal evolution of the boundary layer. The results indicate that the underlying magnetotail magnetic reconnection process was an intrinsically impulsive and the active X-line was located relatively close to the Earth, approximately at 16-18 R_E.

SUBMITTER: Varsani A

PROVIDER: S-EPMC5784414 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm.

Varsani A A Nakamura R R Sergeev V A VA Baumjohann W W Owen C J CJ Petrukovich A A AA Yao Z Z Nakamura T K M TKM Kubyshkina M V MV Sotirelis T T Burch J L JL Genestreti K J KJ Vörös Z Z Andriopoulou M M Gershman D J DJ Avanov L A LA Magnes W W Russell C T CT Plaschke F F Khotyaintsev Y V YV Giles B L BL Coffey V N VN Dorelli J C JC Strangeway R J RJ Torbert R B RB Lindqvist P-A PA Ergun R R

Journal of geophysical research. Space physics 20171103 11

During a magnetic storm on 23 June 2015, several very intense substorms took place, with signatures observed by multiple spacecraft including DMSP and Magnetospheric Multiscale (MMS). At the time of interest, DMSP F18 crossed inbound through a poleward expanding auroral bulge boundary at 23.5 h magnetic local time (MLT), while MMS was located duskward of 22 h MLT during an inward crossing of the expanding plasma sheet boundary. The two spacecraft observed a consistent set of signatures as they s ...[more]

PMID: 29399431

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Project description:Abstract Fast divergent flows of electrons and ions in the magnetotail plasma sheet are conventionally interpreted as a key reconnection signature caused by the magnetic topology change at the X‐line. Therefore, reversals of the x‐component (Vx⊥) of the plasma flow perpendicular to the magnetic field must correlate with the sign changes in the north‐south component of the magnetic field (Bz). Here we present observations of the flow reversals that take place with no correlated Bz reversals. We report six such events, which were measured with the high‐resolution plasma and fields instruments of the Magnetospheric Multiscale mission. We found that electron flow reversals in the absence of Bz reversals (a) have amplitudes of ∼1,000–2,000 km s−1 and durations of a few seconds; (b) are embedded into larger‐scale ion flow reversals with enhanced ion agyrotropy; and (c) compared with conventional reconnection outflows around the electron diffusion regions (EDRs), have less (if ever) pronounced electron agyrotropy, dawnward electron flow amplitude, and electric field strength toward the neutral sheet, although their energy conversion parameters, including the Joule heating rate, are quite substantial. These results suggest that such flow reversals develop in the ion‐demagnetization regions away from electron‐scale current sheets, in particular the EDRs, and yet they play an important role in the energy conversion. These divergent flows are interpreted as precursors of the flow‐driven reconnection onsets provided by the ion tearing or the ballooning/interchange instability. Key Points Transient electron flow reversals embedded into a more gradual ion flow reversal in the magnetotail occur without magnetic topology change Properties of the discovered divergent flows are distinctly different from those of reconnection outflows in the electron diffusion region Divergent flows are interpreted as flow‐driven reconnection onsets due to the ion tearing or the ballooning/interchange instability

Dataset Information

Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm.

Publications

Simultaneous Remote Observations of Intense Reconnection Effects by DMSP and MMS Spacecraft During a Storm Time Substorm.

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