THE EFFECT OF MAGNETOSHEATH PLASMA-FLOW ON FLUX-TRANSFER EVENTS PRODUCED BY THE ONSET OF MERGING AT A SINGLE-X LINE

We present predictions on the signatures of flux transfer events (FTEs ) at the dayside magnetopause by the single X line MHD model based on the subsolar environment: initially in the magnetosheath with backgrou nd flow northward parallel to the dayside magnetopause. In conformity with our previous investigation [Ku and Sibeck, 1997] we choose realis tic parameteres for the simulation with the ratio of rho(msh)/rho(sph) = 10, B-msh/B-sph = 0.5, and T-msh/T-sph = 0.175 along the magnetoshe ath and magnetospheric sides. The localized resistivity turns on near the low northern latitude of dayside magnetopause, and the initial mag nitude of background magnetosheath plasma flow is set 0.15 V-A0 (B-sph /root rho(msh)mu(0)), Or equivalent to 30% of magnetosheath Alfven vel ocity. Simulation results produce signatures of FTEs similar to the pr evious case without the background magnetosheath flow [Ku ann Sibeck, 1997] but different in some respects. Events moving opposite to this f low slow down but intensify, whereas events moving in the direction of the magnetosheath flow accelerate but weaken. Similarly, the satellit e observes no significant signatures of FTEs in the magnetosphere. All the FTEs exhibit asymmetric bipolar magnetic field signatures normal to the magnetopause. Scatterplots versus the plasma density reveal tha t steep changes for the temperature kT, the magnetic field B-z, and th e Alfven velocity occur in the magnetospheric side immediately adjacen t to the magnetopause.