On large plasmoid formation in a global magnetohydrodynamic simulation

Honkonen, Ilja; Palmroth, Minna; Pulkkinen, Tuija; Janhunen, P.; Aikio, Anita

doi:10.5194/angeo-29-167-2011

Cited by 15 publications

(14 citation statements)

References 28 publications

(41 reference statements)

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“…This is probably because Guo et al [2011] underestimated the ring current injection by using a relative larger ring current decay time ( τ = 8 hours). Note that, some substorm‐related tail energy sinks are not considered in studying the energy budget, such as escape energy carried by plasmoids and plasma sheet heating [ Baker et al , 1997; Ieda et al , 1998; Honkonen et al , 2011]. Koskinen and Tanskanen [2002] suggested that a scaling parameter of 1.5–2 should be applied to the coupling parameters to account for some substorm‐related tail energy sinks in calculating the energy input from the solar wind to the magnetosphere.…”

Section: Discussionmentioning

confidence: 99%

Characteristics of magnetospheric energetics during geomagnetic storms

Wang

et al. 2012

J. Geophys. Res.

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[1] To investigate the magnetospheric energetics during magnetic storms, we performed a statistical survey of 307 geomagnetic storms between 1995 and 2009. For the purpose of getting a detailed understanding of the energy processes, we conducted our study of storm-time energetics for three time durations: the main phase, the recovery phase, and the total storm period. We found that the partition of the energy dissipation via the ring current injection and high-latitude ionospheric dissipation is controlled by the storm intensity. The proportion of the ring current injection increases linearly as the storm intensity increases for all three time durations. For moderate storms, the high-latitude ionospheric dissipation is dominant, with only $30% energy dissipated via the ring current; whereas for superstorms, the ring current injection becomes dominant, with $70% energy dissipated via the ring current. We also confirmed the essential and crucial role of the total energy input into the magnetosphere during the main phase in controlling the storm intensity. The total energy input during the main phase is directly proportional to the storm intensity. Their correlation efficiency is as high as 0.85. The storm-time energy budget was also quantified in this study. The coupling efficiency indicates an exponential decay as the storm intensity increases, with the coupling efficiency during the main phase less than that during the recovery phase.

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Section: Discussionmentioning

confidence: 99%

Characteristics of magnetospheric energetics during geomagnetic storms

Wang

et al. 2012

J. Geophys. Res.

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“…The simulation uses solar wind parameters from the ACE satellite as input and the delay time to the dayside magnetopause of 46 min was estimated by Honkonen et al (2011). Figure 4 top panel shows some selected views from the GUMICS simulation.…”

Section: Polar Cap Boundary and Ionospheric Currentsmentioning

confidence: 99%

IMF effect on the polar cap contraction and expansion during a period of substorms

et al. 2013

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The polar cap boundary (PCB) location and motion in the nightside ionosphere has been studied by using measurements from the EISCAT radars and the MIRACLE magnetometers during a period of four substorms on 18 February 2004. The OMNI database has been used for observations of the solar wind and the Geotail satellite for magnetospheric measurements. In addition, the event was modelled by the GUMICS-4 MHD simulation. The simulation of the PCB location was in a rather good agreement with the experimental estimates at the EISCAT longitude. During the first three substorm expansion phases, neither the local observations nor the global simulation showed any poleward motions of the PCB, even though the electrojets intensified. Rapid poleward motions of the PCB took place only in the early recovery phases of the substorms. Hence, in these cases the nightside reconnection rate was locally higher in the recovery phase than in the expansion phase.

In addition, we suggest that the IMF B_z component correlated with the nightside tail inclination angle and the PCB location with about a 17-min delay from the bow shock. By taking the delay into account, the IMF northward turnings were associated with dipolarizations of the magnetotail and poleward motions of the PCB in the recovery phase. The mechanism behind this effect should be studied further

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“…Hence, although substorms appear to be the most commonly investigated feature in the runs, the time instants include all kinds of solar wind conditions (see, e.g. Honkonen et al, 2011), and hence the results will not only be applicable to substorms. Five of the events occur during Northern Hemisphere winter (December-February), one during spring (March-May), two in summer (July-August), and two during the fall (September-November).…”

Section: Imf B Y Dependence Of Energy Transfermentioning

confidence: 99%

Magnetopause energy transfer dependence on the interplanetary magnetic field and the Earth's magnetic dipole axis orientation

2012

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Abstract. We examine the spatial variation of magnetospheric energy transfer using a global magnetohydrodynamic (MHD) simulation (GUMICS-4) and a large data set of flux transfer events (FTEs) observed by the Cluster spacecraft. Our main purpose is to investigate whether it is possible to validate previous results on the spatial energy transfer variation from the GUMICS-4 simulation using the statistical occurrence of FTEs, which are manifestations of magnetospheric energy transfer. Previous simulation results have suggested that the energy transfer pattern at the magnetopause rotates according to the interplanetary magnetic field (IMF) orientation, and here we investigate whether a similar rotation is seen in the locations at which FTE signatures are observed. We find that there is qualitative agreement between the simulation and observed statistics, as the peaks in both distributions rotate as a function of the IMF clock angle. However, it is necessary to take into account the modulation of the statistical distribution that is caused by a bias towards in situ FTE signatures being observed in the winter hemisphere (an effect that has previously been predicted and observed in this data set). Taking this seasonal effect into account, the FTE locations support the previous simulation results and confirm the earlier prediction that the energy transfers in the plane of the IMF. In addition, we investigate the effect of the dipole orientation (both the dipole tilt angle and its orientation in the plane perpendicular to the solar wind flow) on the energy transfer spatial distribution. We find that the energy transfer occurs mainly in the summer hemisphere, and that the dayside reconnection region is located asymmetrically about the subsolar position. Finally, we find that the energy transfer is 10 % larger at equinox conditions than at solstice, contributing to the discussion concerning the semiannual variation of magnetospheric dynamics (known as "the Russell-McPherron effect").

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On large plasmoid formation in a global magnetohydrodynamic simulation

Cited by 15 publications

References 28 publications

Characteristics of magnetospheric energetics during geomagnetic storms

Characteristics of magnetospheric energetics during geomagnetic storms

IMF effect on the polar cap contraction and expansion during a period of substorms

Magnetopause energy transfer dependence on the interplanetary magnetic field and the Earth's magnetic dipole axis orientation

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