Particle-In-Cell Modeling of Martian Magnetic Cusps and Their Role in Enhancing Nightside Ionospheric Ion Escape

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2021-01-16
Major/Subject
Mcode
Degree programme
Language
en
Pages
11
Series
Geophysical Research Letters, Volume 48, issue 1
Abstract
Amongst various escape channels, ion outflow is a major contributor to atmospheric loss at Mars over geologic time. On Mars' nightside, observations have indicated that cusp regions within crustal magnetic fields are associated with phenomena such as accelerated particle populations, discrete auroral emissions, and ionospheric outflow; however, the kinetic physics occurring within crustal magnetic cusps is poorly understood. Here, we present 1.5-dimensional particle-in-cell simulations of magnetospheric-ionospheric interactions within martian crustal magnetic cusp regions of varying strength. Simulation results demonstrate the formation of quasi-static, field-aligned potentials pointing away from Mars that accelerate electrons into the martian atmosphere while accelerating ions away, thereby enhancing ionospheric escape. Escaping ionospheric flux scales with crustal field strength, with 160 nT crustal fields yielding >2× the ion escape flux than in the case with no crustal fields. We discuss these results andconclude that magnetic cusp regions may be significant sources of ion loss at Mars.
Description
Keywords
ambipolar potential, ion escape, magnetic cusps, martian ionosphere, particle-in-cell model
Other note
Citation
Poppe , A R , Brain , D A , Dong , Y , Xu , S & Järvinen , R 2021 , ' Particle-In-Cell Modeling of Martian Magnetic Cusps and Their Role in Enhancing Nightside Ionospheric Ion Escape ' , Geophysical Research Letters , vol. 48 , no. 1 , e2020GL090763 . https://doi.org/10.1029/2020GL090763