Flux transfer events produced by the onset of merging at multiple X lines

We present two-dimensional magnetohydrodynamic model predictions for the si gnatures of flux transfer events (FTEs) at the dayside magnetopause produce d by the onset of merging along two or more extended X lines. We consider t hree scenarios: (1) equal merging rates with identical resistivities south (eta(1)) and north (eta(2)) of the equator, (2) unequal merging rates with eta(1) > eta(2), and (3) equal merging rates in the presence of a backgroun d northward magnetosheath flow velocity(V-z = 0.15B(sph) / root rho(msh)mu( 0)). Realistic ratios of magnetosheath to magnetospheric parameters are cho sen to confirm with in situ observations and our previous simulations [Ku a nd Sibeck, 1997, 1998a, b]: rho(msh)/rho(sph) = 10, B-msh/B-sph = 0.5, and T-msh/T-sph = 0.175. In case 1, a stationary magnetic island forms between two bulges accelerating away from the subsolar point. In case 2, me magneti c island formed between tilt; two X lines pursues the bulge created near th e line with smaller resistivity. In case 3 the island formed between the tw o X lines pursues the bulge by moving in the direction of the background fl ow. All three scenarios produce events with characteristics similar to thos e in the single X line model: strong asymmetric bipolar magnetic fields and plasma velocities normal to the magnetopause in the magnetosheath and no s ignificant signatures in the magnetosphere (with the magnitude of the trail ing pulse exceeding that of the leading edge). However, the islands produce d in cases 2 and 3 also generate more symmetric signatures typical of FTEs in both the magnetosheath and magnetosphere. By comparison with observation s, the transition parameter plots that we present can be used to discrimina te between the merging scenarios.