NUMERICAL SIMULATIONS OF LARGE SCALE EQUATORIAL SPREAD F
大尺度赤道扩展F的数值模拟

We have performed numerical simulations of nonlinear evolution of plasma interchange instability in equatorial spread F(ESF) under different conditions. It is shown that the interchange instability resulting from one-or two-dimensional initial density perturbations can grow into plasma bubbles but cannot evolve into the plumelike structures on the west wall of a plasma bubble .The production of plasma bubbles initiated by gravity waves takes a much shorter time than that resulting from two-dimensional density perturbations. When both a gravity wave and a smaller scale initial density perturbation are used,it is found that the large scale gravity wave determines the outer scale of ESF irregularities and the smaller scale perturbation results in the plumelike structures preferentially located on the west wall. The numerical results show a good agreement with observations.