The Spatial Extent of Magnetopause Magnetic Reconnection From In Situ THEMIS Measurements

Abstract

Magnetic reconnection at the magnetopause has long been studied with multi‐spacecraft observations. In this work, data from the five satellite THEMIS mission during the years of 2008–2010 are used to generate statistics regarding the spatial extent of magnetopause reconnection. The presence of a reconnecting magnetopause is determined with the Walén relation as two satellites cross the magnetopause simultaneously. In some cases both satellites measure reconnection whereas in others one satellite measures reconnection and the other does not. This study finds that two spacecraft are more likely to observe a contiguous reconnection region the closer they are spatially, and that reconnection is not always extended around the entire magnetopause. Plasma β gradient drifts are investigated as a cause of local reconnection suppression. Spacecraft position along the magnetopause flanks is also investigated as a possible spatial limitation to reconnection due to changes in shear flow or boundary thickness.

Magnetospheric Sources of Theta Aurora: A Case Study Comparing Observations With SWMF Global Simulation

“…In short, four‐field junctions are locations that connect all four field topologies: solar wind (no connection to Earth), open connecting to northern hemisphere, open connecting to southern hemisphere, and closed connecting to both hemispheres. While the four‐field junction analysis alone does not imply active reconnection, it does specify the potential locations for reconnection to occur (Atz et al., 2022; Laitinen et al., 2006). The cyan isosurfaces in Figures 3c–3f outline the simulation cells where reconnection might be occurring.…”

Hybrid-Vlasov simulation of soft X-ray emissions at the Earth’s dayside magnetospheric boundaries

“…7d), fluctuations can lead to the appearance of several local maxima in Q int 300s , denoting the existence of structures near the magnetopause nose. These structures might be associated with the nature of the reconnection taking place at the dayside magnetopause, which can either be over an extended X-line or on the contrary more patchy (Atz et al, 2022;Walsh et al, 2017).…”

The Lunar Environment Heliophysics X-ray Imager (LEXI) Mission

“…Reconnection may also be suppressed by a gradient in plasma beta across the current sheet causing a diamagnetic drift (Swisdak et al 2010). Along the dayside magnetopause this is primarily driven by plasma beta and magnetic field variations on the magnetosheath side of the boundary (Phan et al 2013;Atz et al 2022b). Lastly, work to quantify the rate of reconnection at the dayside magnetopause through a physics-based approach incorporates a number of parameters in the solar wind including density, velocity, magnetic field vector, and Alfvén Mach number (Borovsky 2013).…”