Three-dimensional simulations of the ionospheric plasma transport in the presence of the structured field-aligned flows

Recent observations from the Freja and FAST satellites as well as earlier o bservations from OGO 5, Heos 2, and DE 2 indicate the presence of fine stru ctures in the field-aligned plasma flows. We have simulated the effects of such structures on ionospheric plasma transport processes, using our three- dimensional large-scale, multimoment, multifluid model. The model solves th e continuity momentum and double adiabatic energy equations with anisotropi c ion temperatures in the field line coordinates from 1500 km to 10 RE. It includes important physics of the ionosphere-magnetosphere coupling region, such as the mirror force and generalized ambipolar electric field in a dip ole magnetic field geometry. Freja satellite observations of the structured field-aligned currents were used as input parameters in the simulation. It has been shown that in the presence of the field-aligned current filaments with sufficiently small transverse scale sizes, the transverse transport c an play a dominant role in the overall plasma response processes in the ion osphere-magnetosphere coupling region. For example, the local changes in pa rallel flow velocity due to transverse transport, 1 min after the structure d field-aligned current application, may be > 30%. The plasma response time . due to transverse transport has been found to be shorter than that due to parallel transport. The difference is more pronounced at higher altitudes.