The geomagnetic storm and solar eclipse are two important transient phenomena that crucially influence the quiet time ionospheric behavior over the low latitudes. The present study investigates the ionospheric total electron content response to the September-2017 geomagnetic storm and December-2019 annular solar eclipse from global navigation satellite system derived total electron content observations over the Sri Lankan equatorial and low latitude region. Four global navigation satellite system stations at Jaffna (1.21⁰ N), Colombo (1.52⁰ S), Kegalle (1.20⁰ S) and Kalutara (1.84⁰ S) within Sri Lanka were used for the study. The results accentuate a noticeable increase/decrease in the ionospheric total electron content during both the events. The results confirm a positive ionospheric storm effect during the solar flare associated severe geomagnetic storm in September 2017 with the total electron content enhancement of about ~11 total electron content units during the main phase of the storm with the highest variation at Kegalle. The abrupt vertical total electron content flipping during the storm are attributed to the prompt penetration electric fields followed by the disturbance dynamo electric fields during the recovery phase. Concerning the annular solar eclipse in December 2019, the four major features such as pre-ascension, major depression, sunset ascension, and secondary depression were perceptible in the total electron content variation at all stations. Moreover, the ionosphere experienced a clear vertical total electron content depletion of about ~4 total electron content units during the maximum phase of the eclipse with a percentual deviation of 23% over Jaffna and 15% over Colombo than the average quiet day values, indicating an interplay between photoionization production and recombination due to temporary solar interruption. The results would strengthen the understanding of ionospheric variability of the southern hemisphere in the Indian longitude sector.

地磁风暴和日食是两个重要的瞬态现象，对低纬度地区的电离层安静时间至关重要。本研究调查了来自全球导航卫星系统的电离层总电子含量对2017年9月的地磁风暴和2019年12月的环形日食的反应，得出了斯里兰卡赤道和低纬度地区的总电子含量观测结果。贾夫纳（1.21 ⁰  N），科伦坡（1.52 ⁰  S），凯格勒（1.20 ⁰  S）和卡卢塔拉（1.84 ⁰）的四个全球导航卫星系统站 S）在斯里兰卡被用于研究。结果表明，在这两个事件中，电离层总电子含量都有明显的增加/减少。结果证实了在2017年9月太阳耀斑相关的严重地磁风暴期间产生了积极的电离层风暴效应，在风暴的主要阶段中，总电子含量增加了约11个总电子含量单位，在Kegalle的变化最大。暴风雨期间突然的垂直总电子含量突然变化归因于恢复阶段的迅速穿透电场，随后是扰动发电机电场。关于2019年12月的环形日食，这四个主要特征包括预升，大凹陷，日落升华，在所有站的总电子含量变化中都可以看到二次和二次凹陷。此外，电离层在月食的最大相位期间经历了约4个总电子含量单位的明显垂直总电子含量消耗，与平均安静日值相比，贾夫纳和科伦坡的百分比偏差分别为23％和15％，表明由于暂时的太阳能中断，光电离生产和重组之间的相互作用。结果将加强对印度经度区南半球电离层变化的了解。在月食的最大阶段，电离层的垂直总电子含量清除了约4个总电子含量单位，比贾夫纳（Jaffna）和科伦坡（Colombo）的百分偏差比平均安静日值大了23％，表明两者之间存在相互作用由于暂时的太阳能中断而导致的光电离生产和重组。结果将加强对印度经度区南半球电离层变化的认识。在月食的最大阶段，电离层的垂直总电子含量清除了约4个总电子含量单位，比贾夫纳（Jaffna）和科伦坡（Colombo）的百分偏差比平均安静日值大了23％，表明两者之间存在相互作用由于暂时的太阳能中断而导致的光电离生产和重组。结果将加强对印度经度区南半球电离层变化的了解。