Multiple Reconnection X‐Lines at the Magnetopause and Overlapping Cusp Ion Injections

Abstract

Magnetospheric Multiscale (MMS) observations during an extended crossing of the Earth's dayside magnetopause show evidence of multiple reconnections at the boundary. This crossing occurred when the Interplanetary Magnetic Field (IMF) was southward and had a significant BY component. Approximately 2 hr after this crossing, the Twin Rocket Investigation of Cusp Electrodynamics‐2 rockets were launched into the northern hemisphere cusp and observed overlapping cusp ion injections. These overlapping injections are also evidence of multiple reconnections at the magnetopause. Observations more than 2 hr apart do not constitute conjunction between the spacecraft and the rockets. However, the IMF conditions during the magnetopause crossing and the cusp traversal were very similar. Therefore, had the magnetopause crossings and cusp traversals occurred at the same time, the observations would have been similar. Thus, these two events illustrate the link between multiple reconnections at the magnetopause and overlapping cusp ion injections.

TRICE‐2 Rocket Observations in the Low‐Altitude Cusp: Boundaries and Comparisons With Models

“…The solar wind conditions when MMS crossed the magnetopause into the magnetosheath were very similar to the conditions when the TRICE-2 rockets passed through the cusp. At this time, the bulk ion speed was ∼150 km/s (from the MMS Fast Plasma Instrument [Fuselier et al, 2022;Pollock et al, 2016]). Using this speed as a relatively constant average bulk flow speed along the magnetopause surface until reaching the estimated location of the reconnection line several R E above the GSM equatorial plane at the noon meridian (∼6 R E ) yields an additional time of ∼4.2 min.…”

“…Using this speed as a relatively constant average bulk flow speed along the magnetopause surface until reaching the estimated location of the reconnection line several R E above the GSM equatorial plane at the noon meridian (∼6 R E ) yields an additional time of ∼4.2 min. At the reconnection line, the ions were accelerated toward the cusp with an additional speed of V Alfvén = 306 km/s (Fuselier et al., 2022). The field line path from the reconnection point to the low‐altitude cusp (Tsyganenko, 1995) was ∼14 R E .…”

“…The IMF was observed by ARTEMIS-1 to be slightly southward during most of the displayed time; turning abruptly northward at ∼08:30 UT. As shown in the first panel, the tight constellation of the four spacecraft of the NASA Magnetospheric Multiscale (MMS) mission (mean spacecraft separation: 25 km) were within the magnetosheath and traveling outbound, having crossed the magnetopause a couple hours earlier (cf., Fuselier et al, 2022). Variations of the magnetic field clock angle (=tan −1 (B y /B z )) and of the magnetic field intensity are usually preserved across the bow shock in the vicinity of the Earth-Sun line, and are useful for estimating the convection time of the solar wind.…”

“…Section 5 summarizes the investigation and considers future use; especially in relation to upcoming missions such as NASA/TRACERS. Fuselier et al, 2022;Sawyer et al, 2021).…”

Exploring the Solar Wind‐Planetary Interaction at Mars: Implication for Magnetic Reconnection

“…This approach has been used to assess the effect of varying IMF orientation on the occurrence of magnetopause reconnection and, therefore magnetic field circulation, at Earth. Additionally, the “maximum shear model” has been applied to better understand the location of X‐lines during flux transfer events (FTEs) (Petrinec et al., 2020 ) as well as multiple X‐line reconnection events along the terrestrial magnetopause (Fuselier et al., 2022 ). A similar shear angle argument has been applied to predict IMF conditions that favor reconnection along the magnetopause of Mercury (Slavin et al., 2012 ), Jupiter (Desroche et al., 2012 ), Saturn (Fuselier et al., 2020 ), Uranus (Masters, 2014 ), and Neptune (Masters, 2015 ) and Ganymede (Kaweeyanun et al., 2020 ).…”