Basic characteristics of dayside magnetodisc reconnection. (a) Evolution of the three components of the magnetic field: B_r (positive outward), B_θ (positive southward), and B_ϕ (positive counterclockwise). (b) Two components of plasma flow along the equatorial plane, V_r (positive outward) and V_ϕ (positive counterclockwise), in Radial–Theta–Phi coordinates (a spherical coordinate system whose Z axis is Jupiter’s rotation axis pointing north) from 435 : 00–438 : 00 ST. The results were obtained at the position with the maximum B_θ reversal (R = 80.5 R_J, MLT = 06 : 53), marked by green triangles eclosed by black lines in bottom panels. The pink-shaded area represents a magnetic reconnection event. (c–f) Evolution of equatorial B_z (= −B_θ at the equatorial plane, positive northward) in Jupiter’s dayside and near-dayside magnetosphere from 435:00–438:00 ST. Black, magenta, and red lines indicate the B_z zero lines, and green arrows represent plasma flows. Bold black lines represent the magnetopause, which is determined by the contour of B_z = 0. Cyan lines approximate the magnetodisc boundary, which is determined by the contour of the critical density (1.7 cm⁻³), where B_θ/B_z reversals can occur near the simulated inner magnetosphere.