A systematic study of hot O production and escape from Martian atmosphere in response to enhanced EUV Irradiance from Solar Flares

TL;DR

This paper investigates how enhanced EUV radiation from solar flares affects the escape rates of hot atomic oxygen from Mars, revealing a non-linear response with peak escape at moderate flare intensities.

Contribution

It provides a systematic analysis of oxygen escape rates under varying flare intensities and timescales, highlighting the complex non-linear atmospheric response to solar activity.

Findings

Escape flux increases by 40% at 5x flare intensity

Escape flux peaks at 7x flare intensity

Escape flux decreases at 10x flare intensity

Abstract

The study of the evolution of Martian atmosphere and its response to EUV irradiation is an extremely important topic in planetary science. One of the dominant effects of atmospheric losses is the photochemical escape of atomic oxygen from Mars. Increasing the magnitude of the irradiation changes the response of the atmosphere. The purpose of the current paper is to analyze the effects of enhanced EUV irradiation on the escape rates of oxygen atoms. We have used the solar flare of 2017 September 10 as the baseline flare intensity and varied the intensity of the flare from a factor of 3 up to 10 times the baseline flare. We see an increase in the escape flux by 40% for flares up to 5x the intensity of the baseline flare. However, beyond this point, the increase in escape flux tapers off, reaching only about 17% above the baseline. At 10x the baseline flare intensity, the escape flux decreases by nearly 25% compared to the escape rate of the original flare. We also found that the total escape amount of hot O peaks at 7x the original flare intensity. Additionally, we have studied the effects of the time scales over which the flare energy is delivered. We find that energy dissipative processes like radiative cooling and thermal collisions do not come into play instantaneously. The escape flux from higher intensity flares dominate initially, but as time progresses, energy dissipative processes have a significant effect on the escape rate.