July 27, 2015 to August 21, 2015
Nordita, Stockholm
Europe/Stockholm timezone

Three-dimensional kinetic picture of magnetic reconnection, buoyancy and flapping in the magnetotail

Aug 11, 2015, 4:25 PM
FD5 (Nordita, Stockholm)


Nordita, Stockholm

Invited Workshop, August 10-14 Afternoon II


Dr Mikhail Sitnov (JHU/APL)


Magnetic reconnection in the Earth’s magnetotail has important features that distinguish it from similar processes in other space plasma regions, laboratory plasmas and in the simplest theoretical models. First, the very possibility of spontaneous reconnection has been questioned because of the stabilizing effect of electrons magnetized by the north-south (Bz) magnetic field component. Second, magnetotail reconnection often competes with non-reconnection ballooning/interchange and flapping motions, and relative roles of these processes remain unclear. Third, it is distinguished by the so-called dipolarization fronts, kinetic- scale shock- like plasma structures, which dominate the energy conversion. We discuss the kinetic and MHD theory of the magnetotail reconnection onset to identify the equilibria for which the spontaneous reconnection is possible. We show that such equilibria must have a tailward gradient of the Bz field, which is indeed observed in the magnetotail prior to substorm onset. Then we employ 3D full-particle simulations to demonstrate that when the tail becomes unstable with respect to spontaneous growth of reconnection (ion tearing) mode the instability results in the formation of dipolarization fronts. It is accompanied by changes in magnetic topology, which extend in the dawn-dusk direction over the size of the simulation box, suggesting that reconnection onset causes a macroscale reconfiguration of the real magnetotail. The front formation and acceleration is also accompanied by interchange and flapping motions. They significantly disturb the primary dipolarization front but do not destroy it. We find that dipolarization fronts are indeed the main regions of energy conversion in the magnetotail and that the temperature increase near fronts is consistent with recent THEMIS observations. Finally, we discuss virtual satellite observations, which reveal the potential of the present MMS observations in resolving the primary plasma modes associated with the magnetotail reconnection.

Primary author

Dr Mikhail Sitnov (JHU/APL)


Dr Marc Swisdak (University of Maryland, College Park) Dr Viacheslav Merkin (JHU/APL)

Presentation materials