TY - JOUR

T1 - Diamagnetic oscillations ahead of stopped dipolarization fronts

AU - Runov, A.

AU - Sergeev, V. A.

AU - Angelopoulos, V.

AU - Glassmeier, K. H.

AU - Singer, H. J.

PY - 2014

Y1 - 2014

N2 - It is well established that fast flows in the magnetotail plasma sheet which are separated from the ambient plasma by dipolarization fronts brake in the tail-dipole transition region. Flow/front braking is suggested to play an important role in generation of compressional waves in the inner magnetosphere and geomagnetic pulsations. Because of the paucity of multipoint observations in the tail-dipole transition region, however, details of wave generation during flow/front braking are unknown. Using comprehensive coverage of the near-Earth plasma sheet and geostationary orbit by six spacecraft, we explore the relationship between dipolarization fronts that propagated earthward at x=-11 to -9RE and stopped at x=-9 to -8RE and compressional oscillations observed at x≈-8RE. The oscillations, which were diamagnetic (i.e., exhibited antiphase variations in magnetic and plasma pressures), were observed about a minute prior to front detection. The amplitude of the magnetic oscillations at -8RE was ∼5 nT; the wavelength was ∼0.5RE. Enhancements of magnetic oscillations with different frequencies and amplitudes of 1 to 2 and 2 to 4 nT were detected at geosynchronous orbit and on the ground, respectively. Analysis of observations reveals that although the fast flow/front stopped a few RE beyond geosynchronous orbit, the plasma compression propagated farther inward and excited compressional diamagnetic oscillations in the tail-dipole transition region. Key Points Comprehensive coverage of the near-Earth plasma sheet by six spacecrafts Dipolarization front stopped between x=-9 and -8 RE Compressional diamagnetic oscillations were observed ahead of the stopped front

AB - It is well established that fast flows in the magnetotail plasma sheet which are separated from the ambient plasma by dipolarization fronts brake in the tail-dipole transition region. Flow/front braking is suggested to play an important role in generation of compressional waves in the inner magnetosphere and geomagnetic pulsations. Because of the paucity of multipoint observations in the tail-dipole transition region, however, details of wave generation during flow/front braking are unknown. Using comprehensive coverage of the near-Earth plasma sheet and geostationary orbit by six spacecraft, we explore the relationship between dipolarization fronts that propagated earthward at x=-11 to -9RE and stopped at x=-9 to -8RE and compressional oscillations observed at x≈-8RE. The oscillations, which were diamagnetic (i.e., exhibited antiphase variations in magnetic and plasma pressures), were observed about a minute prior to front detection. The amplitude of the magnetic oscillations at -8RE was ∼5 nT; the wavelength was ∼0.5RE. Enhancements of magnetic oscillations with different frequencies and amplitudes of 1 to 2 and 2 to 4 nT were detected at geosynchronous orbit and on the ground, respectively. Analysis of observations reveals that although the fast flow/front stopped a few RE beyond geosynchronous orbit, the plasma compression propagated farther inward and excited compressional diamagnetic oscillations in the tail-dipole transition region. Key Points Comprehensive coverage of the near-Earth plasma sheet by six spacecrafts Dipolarization front stopped between x=-9 and -8 RE Compressional diamagnetic oscillations were observed ahead of the stopped front

KW - compressional waves

KW - dipolarization

KW - fast flow

KW - magnetotail

KW - plasma sheet

UR - http://www.scopus.com/inward/record.url?scp=84899108927&partnerID=8YFLogxK

U2 - 10.1002/2013JA019384

DO - 10.1002/2013JA019384

M3 - Article

VL - 119

SP - 1643

EP - 1657

JO - Journal of Geophysical Research: Biogeosciences

JF - Journal of Geophysical Research: Biogeosciences

SN - 0148-0227

IS - 3

ER -