MAVEN/NGIMS wind observations in the martian thermosphere during the 2018 planet encircling dust event

Abstract

During the 2018 planet encircling dust event (PEDE) at Mars, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft’s Neutral Gas and Ion Mass Spectrometer (NGIMS) was able to take a series of neutral wind observations in the thermosphere at around 150–220 km altitude. These MAVEN observations are the first in-situ measurements of thermospheric wind velocities during a Mars global dust storm. From these measurements, it was found that the observed averaged horizontal thermospheric wind speeds peaked to nearly 200 m/s during the onset of the dust storm before decreasing to about 140 m/s near the peak of the storm. The maximum averaged wind speed observed during the dust storm is not significantly greater than averaged wind speeds at other times, but does represent a local maximum that coincides with the timing of the dust storm. Additionally, throughout the mature and early decay stage of the PEDE, NGIMS wind observations show increased short-scale variability that distinguishes this time period from most other observational periods.