Investigation on the Impact of Solar Flares on the Martian Atmospheric Emissions in the Dayside Near-Terminator Region: Case Studies

Abstract

Solar transient events like flares can cause sudden changes in planetary plasma and neutral environment. However, there is less understanding about their impact on the Martian emissions. Here, we present an investigation of the variability of the Martian atmospheric emissions, viz. OI 130.4 nm, 135.6 nm, CO₂⁺ ultraviolet doublet (UVD), and CO Cameron band (CB) in the dayside near-terminator region during solar flare events. The two X8.2 and M6 class flares during September 2017 on Mars have been selected from existing catalogs. Using data from the imaging ultraviolet spectrograph aboard the Mars Atmosphere and Volatile EvolutioN spacecraft, we examined limb radiance profiles. We observed a significant increase in peak radiance (∼130–140 km) for major emissions with a more pronounced impact beneath the emissions peak during flares compared to quiet time. During solar flares, for 130.4 and 135.6 nm emission, the maximum deviation in radiance beneath peak approaches ∼63% and ∼123%, respectively. Whereas, for CO₂⁺ UVD and CO CB, it is ∼64% and ∼50%, respectively. Additionally, we have presented an average scenario of the dayside near-terminator (solar zenith angle ∼ 70–90°) and observed a notable trend of higher percentage deviation for atomic emissions compared to molecular emissions during flares. Further, our analysis depicts a higher percentage deviation during X8.2 compared to the M6 class flare. This study underscores that during flares, higher irradiance flux and photoelectron impact drive the airglow production processes, leading to enhanced emissions. The case studies offer a novel insight into the significant influence of the varying solar flares intensities on planetary atmospheric emissions.