Search Publications
Control of the topside Martian ionosphere by crustal magnetic fields
Gurnett, D. A.; Edberg, N. J. T.; Němec, F. +4 more
We present observations from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument onboard Mars Express of the thermal electron plasma density of the Martian ionosphere and investigate the extent to which it is influenced by the presence of Mars's remnant crustal magnetic fields. We use locally measured electron densi…
Interpreting Mars ionospheric anomalies over crustal magnetic field regions using a 2-D ionospheric model
Withers, Paul; Mendillo, Michael; Matta, Majd +1 more
spatially inhomogeneous, small-scale crustal magnetic fields of Mars influence the escape of planetary atmospheric species and the interaction of the solar wind with the ionosphere. Understanding the plasma response to crustal magnetic field regions can therefore provide insight to ionospheric structure and dynamics. To date, several localized spa…
Day-to-night transport in the Martian ionosphere: Implications from total electron content measurements
Wei, Y.; Galand, M.; Yelle, R. V. +2 more
The nightside Martian ionosphere is thought to be contributed by day-to-night transport and electron precipitation, of which the former has not been well studied. In this work, we evaluate the role of day-to-night transport based on the total electron content (TEC) measurements made by the Mars Advanced Radar for Subsurface and Ionospheric Soundin…
Concurrent observations of ultraviolet aurora and energetic electron precipitation with Mars Express
Lundin, R.; Bertaux, J. -L.; Gérard, J. -C. +4 more
The database of the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument between late January 2004 and Mars 2014 has been searched to identify signatures of CO Cameron and CO2+ doublet ultraviolet auroral emissions. This study has almost doubled the number of auroral detectio…
Analysis of a coronal mass ejection and corotating interaction region as they travel from the Sun passing Venus, Earth, Mars, and Saturn
Harra, L. K.; Arridge, C. S.; Matthews, S. A. +2 more
During June 2010 a good alignment in the solar system between Venus, STEREO-B, Mars, and Saturn provided an excellent opportunity to study the propagation of a coronal mass ejection (CME) and closely occurring corotating interaction region (CIR) from the Sun to Saturn. The CME erupted from the Sun at 01:30 UT on 20 June 2010,with v≈ 600 km s-…
Total electron content in the Martian atmosphere: A critical assessment of the Mars Express MARSIS data sets
Gurnett, D. A.; Lester, M.; Morgan, D. D. +14 more
The total electron content (TEC) is one of the most useful parameters to evaluate the behavior of the Martian ionosphere because it contains information on the total amount of free electrons, the main component of the Martian ionospheric plasma. The Mars Express Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) radar is able to d…
Evidence of scale height variations in the Martian ionosphere over the solar cycle
Lester, M.; Milan, S. E.; Morgan, D. D. +5 more
Solar cycle variations in solar radiation create density changes in any planetary ionosphere, which are well established in the Earth's case. At Mars, however, the ionospheric response to such changes is not well understood. We show the solar cycle impact on the topside ionosphere of Mars, using data from the Mars Advance Radar for Subsurface and …
MARSIS remote sounding of localized density structures in the dayside Martian ionosphere: A study of controlling parameters
Gurnett, D. A.; Morgan, D. D.; Andrews, D. J. +2 more
Enhanced topside electron densities in the dayside Martian ionosphere have been repetitively observed in areas of near-radial crustal magnetic fields, for periods of tens of days, indicating their long-term spatial and temporal stability despite changing solar wind conditions. We perform a statistical study of these density structures using the io…
Intensity of nightside MARSIS AIS surface reflections and implications for low-altitude ionospheric densities
Gurnett, D. A.; Němec, F.; Morgan, D. D. +1 more
Spacecraft radar sounding signals at frequencies higher than the ionospheric peak plasma frequency are not reflected by the ionosphere. Instead, they make it to the ground where they are reflected by the planetary surface. We analyze the intensity of the surface reflections measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding…