Figure 3. ∣. Observations in the context of reconnection geometry.

P3, P4, P5 and G13 data, in GSM coordinates for G13 or GSM coordinates rotated by ~10° about the Z_GSM axis, to account for the approximate rotation of the field-line planes on THEMIS at that time (M2), obtained from the time period surrounding the X-line passage past THEMIS, plotted in B_z-B_x space. (Per reconnection geometry depicted in Fig. 1C, B_z positive/negative denotes the region earthward/tailward of X-line, respectively, while B_x positive/negative denotes the region above/below the neutral sheet, respectively.) Quantities plotted in color in each panel are: the X- and Y-directed ion velocity V_x, V_y in (A), and (C) respectively; the Y- and Z-directed measured electric field E_y, E_z in (B) and (D) respectively; the measured electric field parallel to the magnetic field E_∥ in (F); the Y-directed magnetic field in (E) and the X-directed electrical current, J_x, in (G) inferred from magnetic field data (M7). Color scales for all panels are saturated to better depict the quantities plotted. A different representation of the same data (not color coded) showing the full range of the quantities and their correlation with B_x or B_z is in Extended Data Fig. 2. The time interval plotted is 04:46:30 to 04:50:00UT (vertical solid lines in Fig. 2) except for small deviations for V_z, B_y, and E_y, (C, E, and D), which are listed in the respective panels in Extended Data Fig. 2 (2C, 2E and 2F). To reduce clutter by random fluctuations, low magnitudes of quantities have been eliminated for V_x, B_y, E_z, and E_∥, (A, E, D, and F, respectively) and those restrictions are also listed in the respective panels in Extended Data Fig. 2 (2A, 2E, 2F, and 2H).