Plasma plume circulation and impact in an MHD substorm

Abstract

[1] We investigate the fate of a plasmaspheric plume generated by a discrete period of southward interplanetary magnetic field (IMF) to assess its contribution to plasma sheet and ring current pressure and compare with that for other sources. We use test particle motions in Lyon-Fedder-Mobarry (LFM) global circulation model fields. The inner magnetosphere is simulated with the Comprehensive Ring Current Model (CRCM) model of Fok and Wolf, driven by the transpolar potential developed by the LFM magnetosphere. A variant of the Ober plasmasphere model is embedded within the models and driven by them. Global circulation is stimulated by a period of southward IMF embedded within a long interval of northward IMF. This leads to the production of a well-defined plasmaspheric plume, enhancing the plasma density sunward of the plasmasphere. Test particles are launched with the properties of plasmaspheric ions on the L = 6.6 R E shell and weighted with densities as specified by the Ober model, as it responds to convection imposed by CRCM. Particles are tracked until they are lost from the system downstream or into the atmosphere, using the Delcourt full equations of motion, implemented for finite element fields. Results are compared with earlier computations of polar and auroral wind outflows. The plume produces an enhanced flow of plasma $10 times the normal polar wind global fluence. However, we find that most of the ''plasmaspheric wind'' is lost from the magnetosphere such that its contribution to the ring current energy density is comparable to that of the normal polar wind for this type of event.

Impact of Solar Wind on the Earth Magnetosphere: Recent Progress in the Modeling of Ring Current and Radiation Belts

“…Ionospheric plasma is highly collisional, and the plasma above ∼500 km is essentially collisionless. It has been recently realized that for a successful description of such a plasma system, a complex solution is needed which allows different physics domains to be described using different physical models (De Zeeuw et al, 2004;Fok et al, 2006;Moore et al, 2008;Ridley et al, 2004;Tóth et al, 2005;Tóth et al, 2011;Zhang, Liemohn, De Zeeuw, Borovsky, Ridley, Toth, Sazykin, Thomsen, Kozyra, Gombosi & Wolf, 2007). This is the reason why coupled models are intensively developed and improved during recent years.…”

Modeling the superstorm in November 2003

“…We will examine their roles in the development of the storm in November 2003. Similar to our previous study [Moore et al, 2008], we release H + and O + ions from the ionosphere and follow their trajectories throughout the magnetosphere using a test-particle code [Delcourt et al, 1990] during the event until they are lost in the solar wind or at the surface of the Earth. The simulation domain for particle tracing is bounded by X = −70 and 15 R E , Y = −30 and 30 R E , and Z = −30 and 30 R E .…”

“…Similar to the approach of Fok et al [2006] and Moore et al [2008], the simulation domain is divided into volume elements of 1 R E 3 and time in intervals of Dt. The density in volume bin j at time t contributed by particle i, which passes through bin j between (t − 0.5 Dt) and (t + 0.5 Dt), is given by…”

“…A noticeable feature was the flow reversal on the dawnside ionosphere. In this paper, we revisit this distinct storm event in November 2003 using our Global Ion Kinetic (GIK) simulation [Moore et al, 2008]. We simulate the global magnetospheric configuration using the Lyon-Fedder-Mobarry (LFM) magnetohydrodynamic (MHD) model [Fedder et al, 1995;Mobarry et al, 1996;Slinker et al, 2001].…”

“…Some of the ions are lost in the solar wind, however, a significant portion are trapped in the plasma sheet and has access to the inner magnetosphere. As in our previous study [Fok et al, 2006;Moore et al, 2008], the CRCM is used to simulate the ring current development and evolutions of the Region 2 current and subauroral convection field. The ion distributions at the CRCM outer boundary at 8 earth radii (R E ) are given by the LFM model (solar wind H + ) and by the density and temperature established from the test-particle calculations (ionospheric H + and O + ).…”