Plasma convection in the magnetotail lobes: statistical results from Cluster EDI measurements

Haaland, Stein; Paschmann, G.; Förster, M.; Quinn, J. M.; Torbert, R. B.; Vaith, H.; Puhl-Quinn, P.; Kletzing, C.

doi:10.5194/angeo-26-2371-2008

Cited by 33 publications

(92 citation statements)

References 49 publications

(73 reference statements)

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“…If neither interval gives a reliable normal, the previous valid orientation is kept. The treatment of ACE data gaps (mainly caused by SWEPAM) is similar to that described in the previous study of Haaland et al (2007) and later also used by Förster et al (2007) and Haaland et al (2008). Data gaps of ACE observations shorter than 10 min are linearly interpolated; for gaps longer than 10 min no reliable reconstructions of solar wind conditions can be given and the EDI data processing is suspended for to the 2-cell-potential patterns in the panels (i) and (a), respectively, with IMFB y + (IMFB y −) orientations (±90 • clock angle).…”

Section: Ace Solar Wind and Imf Datamentioning

confidence: 64%

“…Statistical studies of EDI observations of the magnetospheric convection in various projections have been performed, e.g., by Matsui et al (2004Matsui et al ( , 2005 aiming on the deduction of an electric field model for the inner magnetosphere, and by Noda et al (2003) and in the study of Haaland et al (2008), published in this special issue, on plasma convection in the magnetotail lobes.…”

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confidence: 99%

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High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

et al. 2008

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Abstract. In this study, we investigate statistical, systematic variations of the high-latitude convection cell structure during northward IMF. Using 1-min-averages of Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for six and a half years (February 2001 till July 2007, and mapping the spatially distributed measurements to a common reference plane at ionospheric level in a magnetic latitude/MLT grid, we obtained regular drift patterns according to the various IMF conditions. We focus on the particular conditions during northward IMF, where lobe cells at magnetic latitudes >80 • with opposite (sunward) convection over the central polar cap are a permanent feature in addition to the main convection cells at lower latitudes. They are due to reconnection processes at the magnetopause boundary poleward of the cusp regions. Mapped EDI data have a particular good coverage within the central part of the polar cap, so that these patterns and their dependence on various solar wind conditions are well verified in a statistical sense. On average, 4-cell convection pattern are shown as regular structures during periods of nearly northward IMF with the tendency of a small shift toward negative clock angles. The positions of these high-latitude convection foci are within 79 • to 85 • magnetic latitude and 09:00-15:00 MLT. The MLT positions are approximately symmetric ±2 h about 11:30 MLT, i.e. slightly offset from midday toward prenoon hours, while the maximum (minimum) potential of the high-latitude cells is at higher magnetic latitudes near their maximum potential difference at ≈−10 • to −15 • clock angle for the North (South) Hemisphere. With increasing clock angle distances from ≈IMFB z +, a gradual transition occurs from the 4-cell pattern via a 3-cell to the Correspondence to: M. Förster (mfo@gfz-potsdam.de) common 2-cell convection pattern, in the course of which one of the medium-scale high-latitude dayside cells diminishes and disappears while the other intensifies and merges with the opposite main cell of the same polarity to form the large "round-shaped" convection cell when approaching a well-known IMFB y -dominated configuration. Opposite scenarios with interchanged roles of the respective cells occur for the opposite turning of the clock angle and at the Southern Hemisphere. The high-latitude dayside cells become more pronounced with increasing magnitude of the IMF vector.

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Section: Ace Solar Wind and Imf Datamentioning

confidence: 64%

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confidence: 99%

High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

et al. 2008

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“…The results are based on convection velocity measurements from the Electron Drift Instrument (EDI), combined with electron density measurements obtained from the Electric Field and Wave Experiment (EFW). The two data sets consist of data collected over a period of 7 years from the Cluster mission, and are very similar to the data sets described in Haaland et al (2008) and Svenes et al (2008), respectively.…”

Section: Introductionmentioning

confidence: 97%

“…In the Northern Hemisphere a positive (negative) B y will cause a displacement of the reconnection region so that the newly opened flux tubes are transported towards dawn (dusk), and oppositely for the Southern Hemisphere (e.g., Cowley et al, 1991). This B y influence is also reflected in the convection in the lobes (Gosling et al, 1984(Gosling et al, , 1985Noda et al, 2003;Haaland et al, 2008), the ecliptic plane Baumjohann et al, , 1986Maynard et al, 1990;Matsui et al, 2005), and in the polar cap ionosphere (Ruohoniemi and Baker, 1998;Förster et al, 2007;Haaland et al, 2007). In the Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

Plasma transport in the magnetotail lobes

et al. 2009

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Abstract. The Earth's magnetosphere is populated by particles originating from the solar wind and the terrestrial ionosphere. A substantial fraction of the plasma from these sources are convected through the magnetotail lobes. In this paper, we present a statistical study of convective plasma transport through the Earth's magnetotail lobes for various geomagnetic conditions. The results are based on a combination of density measurements from the Electric Field and Waves Experiment (EFW) and convection velocities from the Electron Drift Instrument (EDI) on board the Cluster spacecraft. The results show that variations in the plasma flow is primarily attributed to changes in the convection velocity, whereas the plasma density remains fairly constant and shows little correlation with geomagnetic activity. During disturbed conditions there is also an increased abundance of heavier ions, which combined with enhanced convection, cause an accentuation of the mass flow. The convective transport is much slower than the field aligned transport. A substantial amount of plasma therefore escape downtail without ever reaching the central plasma sheet.

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“…The electric potential differences in the tail and across the plasma sheet are the result of the solar wind-magnetosphere coupling. This coupling may induce potential differences on the order of several tens of kV; the cross-tail potential, typically 40 kV (Haaland et al, 2008), is an example. There may also be shear flows across such interfaces, for instance, when bursty bulk flows are present with speeds of up to hundreds of km s −1 (Angelopoulos et al, 1992).…”

Section: Plasma and Field Configurationmentioning

confidence: 99%

Electric potential differences across auroral generator interfaces

Keyser

Echim

2013

Ann. Geophys.

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Strong localized high-altitude auroral electric fields, such as those observed by Cluster, are often associated with magnetospheric interfaces. The type of high-altitude electric field profile (monopolar, bipolar, or more complicated) depends on the properties of the plasmas on either side of the interface, as well as on the total electric potential difference across the structure. The present paper explores the role of this cross-field electric potential difference in the situation where the interface is a tangential discontinuity. A self-consistent Vlasov description is used to determine the equilibrium configuration for different values of the transverse potential difference. A major observation is that there exist limits to the potential difference, beyond which no equilibrium configuration of the interface can be sustained. It is further demonstrated how the plasma densities and temperatures affect the type of electric field profile in the transition, with monopolar electric fields appearing primarily when the temperature contrast is large. These findings strongly support the observed association of monopolar fields with the plasma sheet boundary. The role of shear flow tangent to the interface is also examined

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Plasma convection in the magnetotail lobes: statistical results from Cluster EDI measurements

Cited by 33 publications

References 49 publications

High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

Plasma transport in the magnetotail lobes

Electric potential differences across auroral generator interfaces

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