A. Boudouridis

Investigation of magnetopause reconnection models using two colocated, low‐altitude satellites: A unifying reconnection geometry

Ion precipitation data from two co-orbiting Defense Meteorological Satellite Program satellites (F6 and F8) are used to investigate magnetopause reconnection models. We examine differential fluxes between 30 eV and 30 keV, from a Southern Hemisphere, prenoon pass during the morning of January 10, 1990. Data from the first satellite to pass through the region (F6) show two distinct ion energy dispersions ∼1° of latitude apart, between 76° and 79° magnetic latitude. The electron data exhibit similar features at around the Same region but with no or little energy dispersion, consistent with their high velocities. We suggest that the two energy dispersions can be explained by two separate injections resulting from two bursts of magnetopause reconnection. Data from the second satellite (F8), which moved through the same region 1 min later, reveal the same energy-dispersed structures, only further poleward and with less overall flux. This temporal evolution is consistent with two recently reconnected flux tubes releasing their plasma as they move antisunward away from dayside merging sites. However, an observed overlap between the two ion energy dispersions suggests a more complex reconnection geometry than usual models can accommodate. We propose a generalized reconnection scenario that unifies the Bursty Single X-Line and the Multiple X-Line Reconnection models. A simple time-of-flight particle precipitation model is constructed to reproduce the ion dispersions and their overlap. The modeling results suggest that for time-dependent reconnection the dispersion overlap is observed clearly at low altitudes only for a short period compared with the evolution timescale of the ion precipitation.

A new look at the pulsed reconnection model of the dayside magnetopause

Abstract Electron and ion precipitation data from two co-orbiting Defense Meteorological Satellite Program (DMSP) spacecraft (F6 and F8) are used to investigate the model of pulsed magnetopause reconnection. We suggest that the two energy dispersions observed can be explained by two separate injections resulting from two bursts of magnetopause reconnection. However, an observed overlap between the two ion dispersions cannot be explained with the conventional model of bursty magnetopause reconnection. We propose a generalization of the pulsed reconnection model that involves elements of both the bursty single x-line and multiple x-line reconnection models. In the framework of this unified model, the observed electron features can be explained in terms of the “fossil” flux transfer event picture.

Formation of the LLBL in the Context of a Unifying Magnetopause Reconnection Mechanism

A recently proposed unifying magnetopause reconnection mechanism combines elements of the Bursty Single X-line and Multiple X-line Reconnection models. This reconnection scenario is based on ion precipitation data from two co-orbiting Defense Meteorological Satellite Program (DMSP) spacecraft (F6 and F8). The two energy dispersions observed can be explained by two separate injections resulting from two bursts of magnetopause reconnection. However, their observed overlap cannot be explained with the conventional model of bursty magnetopause reconnection, but requires additional assumptions which form the basis of the generalized reconnection scheme. In the framework of this unifying model, the observed electron features of a mixed magnetosheath and magnetospheric population can be explained in terms of the fossil Flux Transfer Event picture. In doing so this model provides a direct way for the formation of the Low-Latitude Boundary Layer (LLBL) via magnetic merging, on both open and closed field lines, at the dayside magnetopause during southward IMF conditions with a strong By component.