Prompt penetration of convection/overshielding electric fields to equatorial and low latitudes during the southward/northward turnings of interplanetary magnetic field (IMF Bz) have been widely studied in the literature. The other types of penetration electric fields due to sudden changes in the solar wind dynamic pressure, IMF By and during the onset of substorms have also been recently reported. In this paper, we present the exclusive role of solar wind density changes on the prompt equatorial electric field disturbances using the long‐term observations of equatorial electrojet (EEJ) from the Indian sector. In response to the sharp increases in the solar wind density, prompt increases/decreases in the EEJ indicating the eastward/westward prompt penetration electric field (PPEF) of ~20 min periods have been consistently observed on the dayside/nightside. The prompt equatorial electric field disturbances of the opposite polarity have also been observed when the density decreases sharply. Further, the polarity of these PPEF disturbances does not show any clear dependency on the direction of IMF Bz and By. This paper is the first report with a statistically significant number of observations on the characteristics of equatorial electric field disturbances in response to the sudden enhancements/decreases in the solar wind density alone on both dayside and nightside. The underlying physical mechanisms for the prompt equatorial electric field disturbances have been discussed in light of enhanced high‐latitude convection and additional field‐aligned currents due to sudden enhancement of solar wind density.

中文翻译：

---

瞬变穿透电场和赤道电喷对太阳风密度的控制

文献中已经广泛研究了对流/超屏蔽电场在行星际磁场（IMF Bz）向南/向北旋转期间向赤道和低纬度的迅速穿透。由于太阳风动压力突然变化而产生的其他类型的穿透电场IMF By最近也有报道说在亚暴期间。在本文中，我们使用来自印度部门的赤道电喷（EEJ）的长期观测结果，介绍了太阳风密度变化对赤道电场瞬变的独特作用。为响应太阳风密度的急剧增加，EEJ中的迅速增加/减少表明在白天/夜晚一直观察到约20分钟的东西向迅速穿透电场（PPEF）。当密度急剧下降时，也观察到了相反极性的快速赤道电场干扰。此外，这些PPEF干扰的极性对IMF Bz和By的方向没有明显的依赖性。。本文是第一份报告，该报告对赤道电场扰动的特征具有统计意义的大量观察结果，这些赤道电场扰动是仅在白天和晚上，太阳风密度突然增加/减小所引起的。鉴于增强的高纬度对流和由于太阳风密度的突然增强而产生的额外的场对准电流，已经讨论了赤道电场瞬变的潜在物理机制。