Thokuluwa Ramkumar
National Atmospheric Research Laboratory, Dept. of Space, Govt. of India, Gadanki, Andhra Pradesh, 517112, India.
Sci Rep. 2025 May 7;15(1):15874. doi: 10.1038/s41598-025-00627-w.
In general, during geomagnetic storm times, equatorial ionospheric plasma bubbles (equivalently plasma depletions) will be generated due to the effect of prompt penetration of magnetosphere-associated disturbed electric fields to the magnetic equatorial region through polar ionosphere under proper background ionosphere conditions. For the 17 March 2015 super geomagnetic storm event, many reports were published elsewhere on observation of generation of equatorial plasma bubbles particularly over the Indian region using ground-based very-high-frequency radars, airglow imagers, Global Positioning Satellite System (GPS) receivers and space-based satellite measurements. Almost all these reports missed to report correctly on this event and even made wrong claims that they observed the generation of equatorial plasma bubbles. The present report makes clarification here by properly scrutinizing the airglow imager data obtained over the Indian station of Gadanki that actually on that day ionospheric plasma "blobs" (plasma enhancements) rather than plasma bubbles were generated during the local evening sunset time. In the later mid-night hours, it is observed the generation of small scale (few km) plasma bubbles from the eastern-walls of plasma blobs. The present work makes it clear that the concept of enhancement in the equatorial ionosphere electron density and the generation of ionospheric plasma blobs during geomagnetic storm period needs to be well taken into account in the physics-based global ionospheric models like the Whole Atmospheric Community Climate - Extended (WACCMX) and SAMI3 is the another model of the ionosphere (SAMI3) as they failed to generate them as reported elsewhere. Further it stresses the importance of successful prediction of severely-modified ionosphere-conditions particularly during geomagnetic storm periods as flawless radio communications between the earth and the outer space face huge challenges even today.
一般来说，在地磁暴期间，在适当的背景电离层条件下，由于磁层相关扰动电场通过极区电离层迅速穿透到磁赤道区域的作用，赤道电离层等离子体泡（等同于等离子体耗尽）将会产生。对于2015年3月17日的超级地磁暴事件，其他地方发表了许多报告，这些报告利用地基甚高频雷达、气辉成像仪、全球定位卫星系统（GPS）接收机和天基卫星测量，特别报道了在印度地区观测到赤道等离子体泡的产生情况。几乎所有这些报告都未能正确报道这一事件，甚至错误地声称他们观测到了赤道等离子体泡的产生。本报告通过仔细审查在印度加丹基站获得的气辉成像仪数据进行了澄清，实际上在当天当地傍晚日落时分产生的是电离层等离子体“团块”（等离子体增强）而非等离子体泡。在午夜后期，观测到从小规模（几公里）的等离子体团块东壁产生了等离子体泡。本研究明确指出，在基于物理的全球电离层模型，如全大气社区气候扩展模型（WACCMX）以及电离层的另一个模型（SAMI3）中，需要充分考虑地磁暴期间赤道电离层电子密度增强和电离层等离子体团块产生的概念，因为这些模型未能像其他地方报道的那样产生这些现象。此外，本研究强调了成功预测严重改变的电离层条件的重要性，特别是在地磁暴期间，因为即使在今天，地球与外层空间之间完美的无线电通信仍面临巨大挑战。
