Extremely enhanced electron density observed by MARSIS in presence of dust storm: Modeling and observations
Abstract
Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) experiment onboard Mars Express (MEX) observed a few events of extremely strong ionizations on 15, 21 and 28 June 2007 at low altitude during the orbits # 4425, 4447 and 4469 at Ls = 258$ ^{o}$, 262$ ^{o}$ and 266$ ^{o}$ respectively. These observations were carried out in the mini-magnetosphere of Mars between latitude 50$ ^{o}$S to 60$ ^{o}$S and longitude 175$ ^{o}$E to 190$ ^{o}$E. The maximum peak electron density ~ 3.75 × 10$ ^{5}$ cm$ ^{−3}$ is observed on 15 June 2007 at altitude 88.48 km. Observation of such strong density at this low altitude demands a source mechanism. In this paper we have modeled electron density profiles due to two mechanisms viz., (1) atmospheric warming due to planet encircling dust storm in Martian Year (MY) 28 and (2) discrete aurora caused by solar X-ray flare and Solar Energetic Particle (SEP), which can account simultaneously for such strong ionization. To carry out the modeling we have used four dimensional Analytical Yield Spectrum (AYS) approach. The modeled electron densities agree reasonably well with the MARSIS observations. However, the modeled peak altitudes are somewhat higher than that of the maximum peak electron density observed by MARSIS. We believe that the lack of solar flux observations for the Martian orbit and the limited field of particle measurement instrument on MEX made the non-observation of a solar transient event like discrete aurora.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.749H