Probing the boundary between antiparallel and component reconnection during southward interplanetary magnetic field conditions

Abstract

[1] One of the major outstanding questions about magnetic reconnection is where reconnection will occur at the Earth's magnetopause for specific conditions of the solar wind and the interplanetary magnetic field (IMF). There are two scenarios discussed in the literature: (1) antiparallel reconnection, which occurs where the magnetospheric magnetic field and the IMF are antiparallel (shear angle of approximately 180°) and (2) component reconnection, where shear angles between the magnetospheric field and the IMF as low as 50°have been reported. The distinction between the two reconnection scenarios is important for the energy and momentum transfer from the solar wind to the magnetosphere. Here we report on a method using three-dimensional plasma observations from the Toroidal Imaging Mass-Angle Spectrograph instrument on the Polar spacecraft as it passes through the northern magnetospheric cusp to calculate the distance to the reconnection line and subsequently trace the distance along model magnetic field lines back to the magnetopause. Results from 130 events reveal that in general, magnetic reconnection occurs along an extended line across the dayside magnetopause (i.e., consistent with the component reconnection scenario). During strong sunward or antisunward IMF conditions (B X ), however, the reconnection location resembles the antiparallel reconnection model at high latitudes and does not cross the dayside magnetopause as a single tilted reconnection line. These results show that either reconnection scenario can occur at the magnetopause, depending on the specific IMF conditions. Citation: Trattner, K. J., J. S. Mulcock, S. M. Petrinec, and S. A. Fuselier (2007), Probing the boundary between antiparallel and component reconnection during southward interplanetary magnetic field conditions,

Magnetospheric Multiscale Science Mission Profile and Operations

“…For MMS mission planning, the maximum shear reconnection model of Trattner et al (2007aTrattner et al ( , 2007b (Fig. 1) provides a relatively simple way to assess the targeting of the Table 1 lists the number of predicted crossings (1224 in Phase 1a and 813 for the shorter Phase 1b) and the number and percentage of crossings that pass within 0.5 R E of the model reconnection line as a function of mission phase for the nominal launch date.…”

“…Fortunately, the location of the reconnection line can be determined using observations in the Earth's magnetospheric cusps (Fuselier et al 2000). From a large number of cusp observations, an empirical model of the reconnection line location was developed (Trattner et al 2007a(Trattner et al , 2007b for conditions when the interplanetary magnetic field (IMF) was southward (B z < 0). This model uses a 3-D magnetopause shape and draping of the IMF (including bending of the field across the shock) to compute the shear in the magnetic field at all points on the magnetopause.…”

“…This region can be envisioned in three dimensions as a ribbon. It is believed to be of the order of 1-10 km thick, 10-100 km wide, and extend for tens of thousands of kilometers over the magnetopause in a continuous or nearly continuous fashion (Hesse et al 2014, this issue;Fuselier et al 2002;Trattner et al 2007aTrattner et al , 2007b. In the magnetotail, the scale sizes may be a factor of about 3 times larger in thickness and width.…”

Double cusp encounter by Cluster: double cusp or motion of the cusp?

“…This also explains the nested crossing of the gap by C1 and C2, with C2 entering the gap first and leaving the gap last. We can estimate from the low energy cut-off of the ion dispersion the distance of injection of the ions, and using the Tsyganenko 1996 model (Tsyganenko, 1995), the location where ions have entered the magnetosphere (see Trattner et al, 2004Trattner et al, , 2007, for the method). Figures 7 and 8 show the distance and source of injection deduced from the ion dispersion observed on C1 and C4, respectively.…”

What Controls the Structure and Dynamics of Earth’s Magnetosphere?

“…Two-point in situ measurements first demonstrated the existence of a stable elongated Xline under southward IMF conditions (Phan et al 2000). However since the magnetopause cannot yet be imaged, 'remote sensing' (in fact ions precipitating into the cusp from the dayside magnetopause) provides an alternative way to probe the magnetopause under a variety of solar wind conditions (e.g., Trattner et al 2007aTrattner et al , 2007b. These results show that if there is a substantial B y (i.e., out of the page in Fig.…”