  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.
