Observations of the cusp region under northward IMF

Pitout, F.; Bosqued, J. M.; Alcaydé, D.; Denig, W. F.; Rème, H.

doi:10.5194/angeo-19-1641-2001

Cited by 16 publications

(23 citation statements)

References 33 publications

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“…The auroral display is then also sensitive to the pulsing nature of the reconnection process in the lobe (Sandholt et al, 1998c(Sandholt et al, , 2001. However, recent observations of the northward IMF cusp by incoherent scatter radars showed no periodic or even quasi-periodic variations in the plasma parameters (Pitout et al, 2001). This is probably due to the weak sunward plasma convection velocity associated with lobe reconnection.…”

Section: Introductionmentioning

confidence: 71%

Simultaneous high- and low-latitude reconnection: ESR and DMSP observations

2002

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Abstract. We present EISCAT Svalbard Radar and DMSP observations of a double cusp during an interval of predominantly northward IMF on 26 November 2000. In the cusp region, the ESR dish, pointing northward, recorded sunward ionospheric flow at high latitudes (above 82 • GL), indicating reconnection occuring in the magnetospheric lobe. Meanwhile, the same dish also recorded bursts of poleward flow, indicative of bursty reconnection at the subsolar magnetopause. Within this time interval, the DMSP F13 satellite passed in the close vicinity of the Svalbard archipelago. The particle measurement on board exhibited a double cusp structure in which two oppositely oriented ion dispersions are recorded. We interpret this set of data in terms of simultaneous merging at low-and high-latitude magnetopause. We discuss the conditions for which such simultaneous highlatitude and low-latitude reconnection can be anticipated. We also discuss the consequences of the presence of two X-lines in the dayside polar ionosphere.

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Section: Introductionmentioning

confidence: 71%

Simultaneous high- and low-latitude reconnection: ESR and DMSP observations

2002

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“…4), is much greater than that outside. However, the density (<10.0 cm −3 ) is lower than average (Pitout et al, 2001). That may be because the crossing is through the outer cusp.…”

Section: Single-point Observationsmentioning

confidence: 84%

“…The data have also revealed the existence of a double cusp structure, and field-aligned currents and plasma instabilities in the cusp (e.g. Bosqued et al, 2001;Krauklis et al, 2001;Gurnett et al, 2001;Taylor et al, 2001;Decreau et al, 2001;Opgenoorth et al, 2001;Pitout et al, 2001;Réme et al, 2001;Cornilleau et al, 2003). Recently, Cargill et al (2005) presented a review of Cluster at the magnetospheric cusps.…”

Section: Introductionmentioning

confidence: 99%

Cluster observations of a structured magnetospheric cusp

et al. 2006

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Abstract. On 18 April 2002 the Cluster spacecraft crossed through the northern outer magnetospheric cusp region during 16:25-17:55 UT when the solar wind dynamic pressure was rather low (<2 nPa) and IMF B z was more negative than IMF B y . The Cluster data from the FGM, CIS, PEACE, EFW, WHISPER and STAFF instruments reveal that the cusp is structured with three anti-sunward ion flow events of durations ≈1.5, 17.5 and 19.0 min, with bulk plasma flow roughly parallel to the magnetopause toward north. The ion and electron densities within the events are much greater than those outside. The zonal electric field in the ion flow events turns eastward as expected from V ×B effect. The sharp inward boundaries of the ion flow events cross the four spacecraft in one time sequence, and the outward boundaries of the events cross the spacecraft in the reverse time sequence. The observations studied using magnetosphere and magnetopause models suggest that the structured cusp is a temporal feature that arises due to three inward and outward movements of the magnetopause by about 1.5 R E so that Cluster, while crossing through the cusp, happened to be in the magnetosheath (ion flow event) and cusp alternately. The magnetopause moved due to the changes in the solar wind dynamic pressure by up to 100%.

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“…In its simplest form, an adiaroic boundary separates the polar regime on open magnetic field lines from the lower-latitude viscous regime on closed field lines, across which plasma cannot enter or leave the polar cap. The boundary between the two regimes has been identified at small IMF clock angles in ion flow measurements by the EISCAT Svalbard radar (ESR) by comparison with the equatorward boundary of redline cusp emission (Pryse et al, 2000b), and it was also a feature of the ESR flow observations of Pitout et al (2001) under B z positive but with variable clock angle. Milan et al (2003) used low level UV aurora in the polar cap, co-located with magnetosheath precipitation, to locate the open/closed magnetic field line boundary under northward IMF, identifying the boundary with the equatorward edge of the emission.…”

Section: Introductionmentioning

confidence: 99%

Ionospheric signatures of the low-latitude boundary layer under conditions of northward IMF and small clock angle

et al. 2006

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Abstract.A case study is presented that concerns the footprints of the low-latitude boundary layer in the highlatitude ionosphere. The measurements were made near local magnetic noon in summertime under conditions of B z >0 and small clock angle. Of particular interest are particle fluxes measured in the region by the NOAA-12 satellite that revealed energetic (>30 keV) electrons, characteristic of trapped particles, together with a population of softer precipitating magnetosheath particles. The particle energydistribution was distinct from those identifying the central plasma sheet at lower latitudes. On its poleward side the layer extended to at least the latitude of the polar cap boundary as identified in ion flows and electron densities measured by the EISCAT Svalbard radar. It is proposed that the particles of the low-latitude boundary layer occurred on newlyclosed magnetic field lines, which were formed by the closure of open polar cap field by lobe reconnection in both Northern and Southern Hemispheres.

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Observations of the cusp region under northward IMF

Cited by 16 publications

References 33 publications

Simultaneous high- and low-latitude reconnection: ESR and DMSP observations

Simultaneous high- and low-latitude reconnection: ESR and DMSP observations

Cluster observations of a structured magnetospheric cusp

Ionospheric signatures of the low-latitude boundary layer under conditions of northward IMF and small clock angle

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