Statistical study of inverted-V structures in FAST data

Partamies, Noora; Donovan, E.; Knudsen, D. J.

doi:10.5194/angeo-26-1439-2008

Cited by 20 publications

(20 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This distribution is similar to the one obtained for the thickness of inverted-V events of precipitating auroral electrons measured by FAST (see Fig. 12 in Partamies et al, 2008) or by DMSP (peak at 28-35 km, Newell et al, 1996).…”

Section: Geometry Of Pcibsupporting

confidence: 68%

“…772 R. Maggiolo et al: Polar cap ion beams during periods of northward IMF those of discrete auroral arcs as observed from the ground. Partamies et al (2008) also reported detection of inverted-V structures at invariant latitudes higher than 80 • . Fieldaligned acceleration by parallel electric fields at high invariant latitude, above the polar caps, has been reported since the 1980s (see the review by Zhu et al, 1997, for a detailed historic account).…”

Section: Introductionmentioning

confidence: 94%

“…Kletzing et al, 1983). Partamies et al (2008) showed that the inverted-V structures associated with precipitating accelerated electrons are mainly located at auroral latitudes (65 • -75 • ) and that their statistical spatial distribution and size are actually similar to Published by Copernicus Publications on behalf of the European Geosciences Union. 772 R. Maggiolo et al: Polar cap ion beams during periods of northward IMF those of discrete auroral arcs as observed from the ground.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Polar cap ion beams during periods of northward IMF: Cluster statistical results

et al. 2011

View full text Add to dashboard Cite

Abstract. Above the polar caps and during prolonged periods of northward IMF, the Cluster satellites detect upward accelerated ion beams with energies up to a few keV. They are associated with converging electric field structures indicating that the acceleration is caused by a quasi-static fieldaligned electric field that can extend to altitudes higher than 7 R E (Maggiolo et al., 2006;Teste et al., 2007).Using the AMDA science analysis service provided by the Centre de Données de la Physique des Plasmas, we have been able to extract about 200 events of accelerated upgoing ion beams above the polar caps from the Cluster database. Most of these observations are taken at altitudes lower than 7 R E and in the Northern Hemisphere.We investigate the statistical properties of these ion beams. We analyze their geometry, the properties of the plasma populations and of the electric field inside and around the beams, as well as their dependence on solar wind and IMF conditions. We show that ∼40 % of the ion beams are collocated with a relatively hot and isotropic plasma population. The density and temperature of the isotropic population are highly variable but suggest that this plasma originates from the plasma sheet. The ion beam properties do not change significantly when the isotropic, hot background population is present. Furthermore, during one single polar cap crossing by Cluster it is possible to detect upgoing ion beams both with and without an accompanying isotropic component.The analysis of the variation of the IMF B Z component prior to the detection of the beams indicates that the delay between a northward/southward turning of IMF and the appearance/disappearance of the beams is respectively ∼2 h and 20 min. The observed electrodynamic characteristics of high altitude polar cap ion beams suggest that they are closely connected to polar cap auroral arcs. We discuss the impliCorrespondence to: R. Maggiolo (romain.maggiolo@aeronomie.be) cations of these Cluster observations above the polar cap on the magnetospheric dynamics and configuration during prolonged periods of northward IMF.

show abstract

Section: Geometry Of Pcibsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Polar cap ion beams during periods of northward IMF: Cluster statistical results

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Although we assumed the adiabatic transport of the magnetospheric electrons to estimate the field-aligned potential difference, the estimated potential difference is well consistent with those reported by other researchers using ionospheric satellite data [e.g., Burch et al, 1976;Bosqued et al, 1986;Reiff et al, 1988;Shiokawa and Fukunishi, 1991;Marklund et al, 2011]. Recently, a statistical study by Partamies et al [2008] using a huge number of inverted-V events observed by Fast Auroral Snapshot (FAST) from 1997 to 2001 showed that the typical maximum energies of the inverted-V events are 2-4 keV, mainly less than 6 keV.…”

Section: Discussionsupporting

confidence: 83%

A statistical study of plasma sheet electrons carrying auroral upward field-aligned currents measured by Time History of Events and Macroscale Interactions during Substorms (THEMIS)

et al. 2011

View full text Add to dashboard Cite

We have statistically investigated the electron density ne,M and temperature Te,M in the near‐Earth plasma sheet in terms of the magnetosphere‐ionosphere coupling process, as measured by the electrostatic analyzer (ESA) on board the Time History of Events and Macroscale Interactions during Substorms (THEMIS‐D) satellite from November 2007 to January 2010. To find out when and where an aurora can occur, either with or without electron acceleration, the thermal current j∥th and the conductivity K along the magnetic field line were also estimated from observations of the magnetospheric electrons with pitch angle information inside 12 RE. The thermal current, j∥th(∝ ne,M Te,M1/2), represents the upper limit of the field‐aligned current that can be carried by magnetospheric electrons without a field‐aligned potential difference. The conductivity, K(∝ ne,M Te,M−1/2), relates the upward field‐aligned current, j∥, to the field‐aligned potential difference, V∥, assuming adiabatic electron transport. The thermal current is estimated by two methods: (1) from the relation by using ne,M and Te,M and (2) from the total downward electron number flux. We find that in the dawnside inner magnetosphere, the thermal currents estimated by both methods are sufficient to carry typical region 2 upward field‐aligned current. On the other hand, in the duskside outer magnetosphere, a field‐aligned potential difference is necessary on the region 1 current since the estimated thermal current is smaller than the typical region 1 current. By using the relationship, j∥ = KV∥, where K is the conductivity estimated from Knight's relation and j∥ is the typical auroral current, we conclude that a field‐aligned potential difference of V∥ = 2–5 kV is necessary on the duskside region 1 upward field‐aligned current.

show abstract

“…Satellite measurements have shown that the inverted-V structures have dimensions of a few hundred kilometers in latitude, and rocket measurements have shown that they are several kilometers (Heikkila, 1970;Frank and Ackerson, 1971;Arnoldy, 1974;Bosqued et al, 1985;Carlson et al, 1998). Recently, 5 years of the Fast Auroral SnapshoT Explorer (FAST) data have shown that the usual width of an inverted-V varies from 20 to 40 km, which is comparable to the peak value of the typical mesoscale auroral arc width of 10-20 km (Partamies et al, 2008). From Freja and Cluster observations, the scale sizes of auroral electric field structures were reported to be ∼ 1-5 km (Karlsson and Marklund, 1996;Johansson et al, 2007).…”

Section: Introductionmentioning

confidence: 98%

Relating field-aligned beams to inverted-V structures and visible auroras

Lee

Parks

et al. 2015

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. The ion composition experiment on Cluster measures 3-D distributions in one spin of the spacecraft (4 s).These distributions often measure field-aligned ion beams (H + , He + and O + ) accelerated out of the ionosphere. The standard model of these beams relies on a quasi-static Ushaped potential model. The beams contain important information about the structure and distribution of the U-shaped potential structures. For example, a simple beam with a narrow velocity range tells us that the particles are accelerated going through a quasi-static U-shaped potential structure localized in space. A more complex beam with a large range of velocities varying smoothly (a few tens of kilometers per second to > 100 km s −1 ) tells us that the potential structure is extended and distributed along the magnetic field. The Cluster experiment has now revealed new features about the beams. Some beams are broken into many individual structures each with their own velocity. The U-shaped potential model would interpret the new features in terms of particles accelerated by narrow isolated potential structures maintained over an extended region of the magnetic field. Another interpretation is that these features arise as Cluster traverses toward the center of a small-scale U-shaped potential region detecting particles accelerated on different equipotential contours. The estimate of the distance of the adjacent contours is ∼ 590-610 m at a Cluster height of ∼ 3.5 R E . The observed dimensions map to ∼ 295-305 m in the ionosphere, suggesting Cluster has measured the potential structure of an auroral arc.

show abstract

Statistical study of inverted-V structures in FAST data

Cited by 20 publications

References 32 publications

Polar cap ion beams during periods of northward IMF: Cluster statistical results

Polar cap ion beams during periods of northward IMF: Cluster statistical results

A statistical study of plasma sheet electrons carrying auroral upward field-aligned currents measured by Time History of Events and Macroscale Interactions during Substorms (THEMIS)

Relating field-aligned beams to inverted-V structures and visible auroras

Contact Info

Product

Resources

About