A Case Study on the Impact of Interplanetary Coronal Mass Ejection on the Martian O(1S) 557.7 nm Dayglow Emission Using ExoMars TGO/NOMAD-UVIS Observations: First Results

We report, for the first time, the impact of interplanetary coronal mass ejections (ICME) on the recently discovered O(¹S) 557.7 nm dayglow emission in the Martian atmosphere. While there are a few studies on the seasonal variation of 557.7 nm dayglow emission available in the literature, the impact of ICME has not been investigated so far. Using the instruments aboard the ExoMars-TGO and Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, we show that the primary emission peak (75–80 km) remains unaffected during ICME events compared to quiet-times. However, an enhancement has been observed in the brightness of the secondary emission peak (110–120 km) and the upper altitude region (140–180 km). The enhancement is attributed to the increased solar electrons, X-ray fluxes and Solar Energetic Particles, augmenting the electron-impact processes causing the enhancement in the brightness. Thus, this study has an implication to the brightness of Martian upper atmosphere during intense solar transients like ICME.