First medium energy neutral atom (MENA) Images of Earth's magnetosphere during substorm and storm‐time

Pollock, C. J.; Asamura, Kazushi; Balkey, M. M.; Burch, J. L.; Funsten, H. O.; Grandé, M.; Gruntman, M.; Henderson, M. G.; Jahn, J. M.; Lampton, M.; Liemohn, Michael W.; McComas, D. J.; Mukai, T.; Ritzau, S. M.; Schattenburg, Mark L.; Scime, Earl; Skoug, R. M.; Valek, P. W.; Wüest, M.

doi:10.1029/2000gl012641

Cited by 61 publications

(50 citation statements)

References 20 publications

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“…In situ measurements are consistent with this asymmetry (e.g., Frank, 1970;de Michelis et al, 1997;Grafe, 1999). One of the first great successes of energetic neutral atom (ENA) imaging was experimental confirmation of this asymmetry (Roelof, 1987;Henderson et al, 1997;Pollock et al, 2001;Mitchell et al, 2001;Reeves and Spence, 2001). In fact, the images in Mitchell et al (2001) capture the dramatic conversion of open to closed drift paths (asymmetric to symmetric ring current) during a step-like transition to northward Bz in the main phase of a large magnetic storm.…”

Section: Introductionsupporting

confidence: 51%

Ring Current Energy Input and Decay

Kozyra

Liemohn

2003

Space Science Reviews

122

104

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Abstract.A new view of the ring current as an active element in the geospace system has emerged in which the ring current responds not only to changing convection electric fields imposed by solar wind interactions but to internal dynamics of the magnetosphere-ionosphere-atmosphere (geospace) system. Variations in the plasma sheet density, temperature and composition, saturation of the polar cap potential drop (and presumably the cross-tail potential drop), modifications to the imposed convection potential in the inner magnetosphere due to ring current shielding effects, the presence of a pre-existing ring current population, storm-substorm coupling, and strong convection with and without accompanying substorm activity all have an impact on the ring current strength, formation and loss. All of these internal processes imply that the geoeffectiveness of a solar wind driver cannot be predicted on the basis of the characteristics of the driver alone but must reflect key aspects of the dynamically changing geospace environment, itself. This review gives a summary of new information on ring current input and decay processes focusing on implications for the global geospace response to solar wind drivers during magnetic storms and on open questions that can be addressed with new ENA imaging techniques.

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Section: Introductionsupporting

confidence: 51%

Ring Current Energy Input and Decay

Kozyra

Liemohn

2003

Space Science Reviews

122

104

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“…The particles inside geostationary orbit are identified as the ring current particles. It is now accepted that the storm-time ring current is usually not a ring at all, but rather a partial (asymmetric) ring, especially in the main phase and early recovery phase of storms (Liemohn et al, 2001;Mitchell et al, 2001;Pollock et al, 2001). Several studies have shown large asymmetries in magnetic field and particle data of the inner magnetosphere (Lui, 2003;Le et al, 2004;Jorgensen et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Distortions of the magnetic field by storm-time current systems in Earth's magnetosphere

et al. 2010

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Abstract. Magnetic field and current system changes in Earth's inner magnetosphere during storm times are studied using two principally different modeling approaches: on one hand, the event-oriented empirical magnetic field model, and, on the other, the Space Weather Modeling Framework (SWMF) built around a global MHD simulation. Two storm events, one moderate storm on 6-7 November 1997 with Dst minimum about −120 nT and one intense storm on 21-23 October 1999 with Dst minimum about −250 nT were modeled. Both modeling approaches predicted a large ring current (first partial, later symmetric) contribution to the magnetic field perturbation for the intense storm. For the moderate storm, the tail current plays a dominant role in the eventoriented model results, while the SWMF results showed no strong tail current in the main phase, which resulted in a poorly timed storm peak relative to the observations. These results imply that the the development of a ring current depends on a strong force to inject the particles deep into the inner magnetosphere, and that the tail current is an important external source for the distortions of the inner magnetospheric magnetic field for both storms. Neither modeling approach was able to reproduce all the variations in the B x and B y components observed at geostationary orbit by GOES satellites during these two storms: the magnetopause current intensifications are inadequate, and the field-aligned currents are not sufficiently represented. While the event-oriented model reproduces rather well the B z component at geostationary orbit, including the substorm-associated changes, the SWMF field is too dipolar at these locations. The empirical model is a useful tool for validation of the first-principle based models such as the SWMF.

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“…The energetic neutral atom (ENA) images [Mitchell et al, 2001;Pollock et al, 2001 ] obtained by the IMAGE satellite [Burch, 2001 ] provide revealing new views of the Earth's magnetosphere. In this paper, we show that we can obtain information about trapped ions from the ENA images.…”

Section: Deconvolution Technique I Introductionmentioning

confidence: 99%