Energy conversion in a compressed magnetospheric separatrix: Observations and simulations

Magnetic reconnection is a fundamental process that is ubiquitous in the universe. It converts magnetic field energy into heating and acceleration of plasma. On the dayside of the Earth’s magnetosphere, it is responsible for the dominant transport of plasma, momentum, and energy across the magnetopause from the solar wind into the Earth’s magnetosphere. The present study reports on a magnetic reconnection event with a guide field (BM=0.5 B) detected by the Magnetospheric Multiscale mission (MMS) on October 21, 2015, around 04:39:24 UT. The MMS traversed the compressed magnetospheric separatrix and the reconnection jet far from the diffusion regions and in specific conditions: observing magnetospheric cold ions and a large magnetosheath density of up to 150 p/cc. We investigate the generalized Ohm’s law and the energy conversion process in the spacecraft frame (J.E) and in the fluid frame (J.E`) associated with the separatrix crossing under such conditions. We further validate and compare our results using 2D fully kinetic simulation.