Martian M2 peak behavior in the dayside near-terminator ionosphere during interplanetary coronal mass ejections

TL;DR

This study investigates how interplanetary coronal mass ejections affect the Martian ionospheric M2 peak, revealing increased peak height and decreased density during disturbed conditions using MAVEN data.

Contribution

It is the first to analyze the influence of ICMEs on the M2 peak parameters (Nm and hm) of the Martian ionosphere using observational data.

Findings

M2 peak height increases during ICMEs (4-16 km)

M2 peak density decreases during ICMEs (0.41-2.8×10^10 m^-3)

Large vertical pressure gradients and electron temperature enhancements are linked to ionospheric variability.

Abstract

The interplanetary coronal mass ejections (ICMEs) can pose significant impacts on the Martian ionosphere, resulting in plasma depletion, variability, and escape to space. However, the connections between the ICMEs and the associated responses of the dayside near-terminator Martian ionospheric primary peak (M2) are not well understood. The present study primarily investigates the behavior of the ionospheric peak density (Nm) and height (hm) during the passage of ICMEs using observations from the Radio Occultation Science Experiment (ROSE) aboard MAVEN spacecraft. We have selected 8 such ICMEs (during 2017-2022) at Mars from the existing catalogs and studied the ROSE electron density profiles during quiet and disturbed time (ICMEs) for identical solar zenith angle range. We observed the elevation of the M2 peak (hm ~4-16 km) during disturbed time (ICMEs) with a decrease in Nm (0.41-2.8*10^10 m-3) in comparison to the quiet time. The present study, for the first time, addressed the influence of ICMEs on the M2 peak parameters (Nm and hm). We have proposed that the development of large vertical pressure gradient and electron temperature enhancement are plausible causes for ionospheric variability. Therefore, the present study provides new insights to understand peak plasma behavior in the dayside near-terminator ionosphere during ICMEs.