Magnetospheric plasma sources and losses: future directions

Walker, R. J.; Williams, D. J.; Christon, S. P.; Hultqvist, B.; Paschmann, G.; Treumann, R. A.

doi:10.1007/978-94-011-4477-3_8

Cited by 19 publications

(30 citation statements)

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“…Specifically, the processes leading to the energization of heavy ions in the ionosphere and subsequent escape to the magnetosphere have been the focus a great deal of observation and modeling [Hultqvist et al, 1999]. It seems reasonable that the field-aligned ion upflows seen by ground-based radar are the seeds of the outflowing cold O+, H+ population seen at satellite altitudes.…”

Section: Introductionmentioning

confidence: 99%

SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

et al. 2007

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[1] The SERSIO sounding rocket was launched from Ny-Alesund, Svalbard, into a type 2 ion upflow event simultaneously observed by the European Incoherent Scatter (EISCAT) radar facility in Longyearbyen on 22 January 2004 at 0857 UT. It reached an apogee of 782 km. In situ wave data and thermal particle measurements in the cusp/cleft region clearly show core thermal ion temperature enhancements up to 0.8 eV in association with 0-4 kHz broadband extremely low frequency wave activity (BBELF). The in situ observation of wave heating in the cusp/cleft region at these low altitudes (520-780 km) and high densities (80,000/cm 3 ) is an important measurement and should be included in any model of ion energization. Wave activity in the form of naturally enhanced ion acoustic lines (NEIAL) was seen by the EISCAT radar in the same activity region. Periods of NEIAL were compared with in situ auroral electron data that show no evidence of a bump-on-tail distribution; thus our data do not support using Langmuir turbulence to explain these radar echoes. In contrast, these observations associating NEIAL with BBELF activity suggest that they may be the same phenomenon. During these comparisons, all-sky camera images were used to verify similar environmental conditions between the rocket and radar measurement volumes, while the spatial separation between the volumes was less than 500 km. In situ measurements also confirm the link between soft electron precipitation and thermal electron temperature enhancements in this ion upflow environment.

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Section: Introductionmentioning

confidence: 99%

SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

et al. 2007

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“…O + ) are continuously expelled from Earth's ionosphere and act as a significant source of plasma in the magnetosphere (e.g. Yau and André, 1997;Hultqvist et al, 1999). Long-term average data of O + ions at mid-altitudes (6000-24 000 km) and at speeds above the gravitational escape show that the outflow is solar cycle and geomagnetic activity dependent, with a global mean rate of the order of 7.2×10 25 ions s −1 (Yau et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

Survey of energetic O<Sup>+</sup> ions near the dayside mid-latitude magnetopause with Cluster

et al. 2005

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Abstract. Since December 2000, the Cluster satellites have been conducting detailed measurements of the magnetospheric boundaries and have confirmed the unambiguous presence of ions of terrestrial origin (e.g. O + ) in regions adjacent to the dayside, mid-latitude magnetopause. In the present paper, we focus on the statistical properties of the O + ion component at energies ranging from 30 eV up to 40 keV, using three years of ion data at solar maximum from the Cluster Ion Spectrometry (CIS) experiment aboard two Cluster spacecraft. The O + density decreases on average by a factor of 6, from 0.041 to 7×10 −3 cm −3 when crossing the magnetopause from the magnetosphere to the magnetosheath, but depends on several parameters, such as the geomagnetic activity or the modified disturbed storm time index (D st * ), and on their location. The O + density is significantly higher in the dusk-side than in the dawn side region, which is consistent with the view that they originate mainly from the plasma sheet. A remarkable finding is that inward of the magnetopause, O + is the dominant contributor to the mass density 30% of the time on the dusk-side in comparison to 3% in the dawnside and 4% near noon. On an event basis in the dusk flank of the magnetopause, we point out that O + ions, when dominating the mass composition, lower the threshold for generating the Kelvin-Helmholtz instability, which may allow plasma exchange between the magnetosheath and the plasma sheet. We also discuss the effect of a substantial O + ion component when present in a reconnection region.

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“…Since the discovery of energetic O + ions at magnetospheric altitudes by Shelley et al (1972), many satellite observations consistently demonstrated that the Earth's ionosphere acts as a significant source of magnetospheric plasma (Chappell et al, 1987;Hultqvist et al, 1999). Statistical studies from earlier satellite missions point out that the total mass supply is…”

Section: Introductionmentioning

confidence: 99%

Multipoint analysis of the spatio-temporal coherence of dayside O<sup>+</sup> outflows with Cluster

et al. 2004

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Abstract. The spatial distribution of ionospheric ion outflow from the dayside cusp/cleft has previously been studied in great detail with numerous satellite missions, but only statistically. Between July and November 2001, the orbit configuration of the Cluster multi-satellite system close to its perigee (4 Earth radii) allows for delay times between spacecraft of about 4 and 35 min in crossing the cusp/cleft. This enables for the first time to assess the spatial and temporal coherence of O + ion outflow on time scales of the order of the satellite time lag. After presenting two contrasting events in detail, O + velocities and outflow intensities from three spacecraft, available on 18 events, all with a similar orbit, have been cross-correlated to quantify the degree of coherence in the outflow. The main result from the analysis is that, although dayside outflows are a permanent feature, steady-state conditions are surprisingly never achieved. In particular, a significant variability is found for convection drift and local outflow intensities on small time scales. This variability of local intensities is not found to depend on the total strenghth of the outflow, which is much more stable and increases with the dynamic solar wind pressure.

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Magnetospheric plasma sources and losses: future directions

Cited by 19 publications

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SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

Survey of energetic O<Sup>+</sup> ions near the dayside mid-latitude magnetopause with Cluster

Multipoint analysis of the spatio-temporal coherence of dayside O<sup>+</sup> outflows with Cluster

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Magnetospheric plasma sources and losses: future directions

Cited by 19 publications

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SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

SERSIO: Svalbard EISCAT Rocket Study of Ion Outflows

Survey of energetic O&lt;Sup&gt;+&lt;/sup&gt; ions near the dayside mid-latitude magnetopause with Cluster

Multipoint analysis of the spatio-temporal coherence of dayside O&lt;sup&gt;+&lt;/sup&gt; outflows with Cluster

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Product

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Survey of energetic O<Sup>+</sup> ions near the dayside mid-latitude magnetopause with Cluster

Multipoint analysis of the spatio-temporal coherence of dayside O<sup>+</sup> outflows with Cluster