Sinuous Aurora at Mars: exploring a new phenomenon with data and models
Abstract
Since their discovery in 2005, discrete UV aurora at Mars have been studied using a combination of in situ and remote sensing data from the MAVEN and Mars Express missions, with ~220 published detections establishing dependence on crustal magnetic field strength and geometry and local time as well as heliospheric conditions. Benefiting from a large orbit and high-sensitivity, the Emirates Mars mission EMUS instrument has provided the first opportunity to regularly image Mars' discrete FUV aurora synoptically. This has revealed a dramatic but uncommon type of emission, in long serpentine filaments, dubbed sinuous aurora (example shown in figure 1). Sinuous aurora patterns typically connect to the dayside. Their shapes shift moderately over ~20 minute timescales and their overall orientation can change by up to 90° over the course of several hours. They appear more prevalent following the arrival of stream interaction regions (SIRs) whereby the By component of the IMF shifts from westward to eastward, a trait they share with trans-polar arcs known as Theta aurora on earth. One hypothesis is that sinuous aurorae are a projection onto the nightside of Mars' magnetotail current sheet under conditions providing sufficient flux and/or energization of electrons. We explore drivers of their shapes and orientations using MAVEN upstream measurements, global MHD simulations and empirical models of tail geometry. We investigate suprathermal electron data from MAVEN SWEA for signatures consistent with sinuous Aurora over the last several years. EMM EMUS promises to be an invaluable tool in helping to understand the drivers of Martian Aurora.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMSM26A..05L