资源环境科技发展态势分析平台

The most important driver of geomagnetic activity is the north-south (B-z) component of the interplanetary magnetic field (IMF), which dominates the solar wind-magnetosphere coupling and all solar wind coupling functions. While the east-west (B-y) IMF component is also included in most coupling functions, its effect is always assumed to be symmetric with respect of its sign. However, recent studies have shown that, for a fixed value of any coupling function, geomagnetic activity is stronger for B-y > 0 than for B-y < 0 in Northern Hemisphere winter. In Southern Hemisphere winter, the dependence on the By sign is reversed. In this paper, we use measurements of National Oceanic and Atmospheric Administration Polar-Orbiting Operational Environmental Satellites to show that the flux of magnetospheric electrons precipitating into the atmosphere also exhibits an explicit By dependence. This B-y dependence is strong in the midnight and dawn sectors where it causes a related By effect in the westward electrojet and geomagnetic activity by modulating ionospheric conductivity.