Mars ionospheric response to solar wind variability

Abstract

At planets with induced magnetospheres, the coupling between the ionosphere, the weak draped magnetosphere, and the solar wind is very direct in comparison to Earth. The weak induced magnetosphere itself is created by the prevailing Solar wind conditions and therefore in its shape and strength dynamically depending on it. In early 2010, Mars was located behind Earth in the Solar wind; thus, we can use coordinated data from multiple near‐Earth spacecraft (Stereo, Wind) to evaluate what kind of Solar wind disturbances have passed by Earth and might consecutively hit Mars, and when. We employ plasma data from the ESA Mars‐Express mission, the ASPERA‐3 particle instrument, and the MARSIS Active Ionospheric Sounder (AIS) to investigate, for a number of isolated events in March and April 2010, how the ionosphere and the induced magnetosphere at Mars develop and decay in response to Solar wind variability in the magnetic field, density, and velocity. In a dedicated campaign mode, we use frequent long‐duration MARSIS AIS operations for several consecutive orbits, to monitor for the first time the long‐term development of the Martian plasma environment during solar wind disturbances. We find that the magnetosphere and ionosphere of Mars can become considerably compressed by solar wind dynamic pressure variations, which usually are also associated with changes in the magnetic draping of the interplanetary magnetic field around the planet. These are typically associated with corotating interaction regions and coronal mass ejections, and can last for several days. During such episodes of compression, we see signatures of increased plasma transport over the terminator and enhanced ion outflow from the upper atmosphere.

Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) after nine years of operation: A summary

“…Another use of this combination of data is found in the study of space weather effects, for example, as reported by Opgenoorth et al (2013). In this study, done during an Earth-Mars period of conjunction, the effects of three space weather events, including corotation interaction regions (CIRs) and coronal mass ejections (CMEs) were studied using ASPERA-3 IMA and ELS data with the MARSIS local electron densities.…”

“…These authors observed compression of the ionosphere with energization of the plasma in the region between the magnetosheath and ionosphere. A study by Morgan et al (2014) of a single CME interaction with the Martian ionosphere, reports the compression of the ionosphere as seen by Opgenoorth et al (2013) with apparent oscillations visible in both local electron density and local magnetic field strength. These authors also observe an extension of the ionosphere well beyond the terminator with disturbed and possibly turbulent plasma.…”

Recovery and validation of Mars ionospheric electron density profiles from Mariner 9

“…Mars Express has operated during a prolonged and deep solar minimum, when solar wind dynamic pressures have been weak. Strong solar wind dynamic pressures depress the top of the ionosphere, which favors a "one scale height" morphology and which also reduces electron densities at high altitudes (Brain 2006;Crider et al 2003;Opgenoorth et al 2013). A strong solar wind dynamic pressure is likely to lead to greater penetration of a horizontal magnetic field into the ionosphere, which would suppress the vertical transport of plasma and may therefore favor a "one scale height morphology".…”

Mars atmospheric losses induced by the solar wind: Comparison of observations with models

“…During several CIR events O + outflow increased by 10 or more times (Wei et al, 2012). Number of CIR and ICME events lead to compression of ionosphere and magnetosphere (Opgenoors et al, 2013).…”