Large-scale ionospheric disturbances due to the dissipation of convectively-generated gravity waves over Brazil

摘要

In a companion paper, we show that large-scale secondary gravity waves and circulation cells are created by the body forces generated by the dissipation of convectively generated gravity waves over Brazil on 01 October 2005. In this paper, we show that these fluid perturbations cause large-scale perturbations of the plasma drift and plasma density in the ionosphere by changing the wind dynamo and transport. These fluid perturbations modify both the amplitude and direction of the plasma drifts. Near the geomagnetic equator, the magnitude of the pre-reversal enhancement can be increased or weakened, depending on the location and local time. Because the circulation cells persist from late afternoon through midnight, the modulation of the vertical drift near the geomagnetic equator persists until midnight. The largest changes of the wind-driven currents can occur either in the E or F region and are determined by the magnitudes of the wind perturbations, conductivities, and conductivity perturbations. The contributions to the plasma transport changes are from advection by the neutral winds along field lines, plasma drifts, and ambipolar diffusion, in the order of their relative significance in the numerical results.