Martian Thermospheric Warming Associated With the Planet Encircling Dust Event of 2018

Abstract

We report the first observations of Martian thermospheric warming associated with the Planet Encircling Dust Event (PEDE) of 2018. We used dayglow observations made by the Imaging Ultraviolet Spectrograph instrument aboard the MAVEN spacecraft to retrieve the upper atmosphere temperature structures. Our analysis shows that the two‐cell meridional circulation pattern may be operating before the PEDE‐2018, which resulted in the cooling of lower/middle latitudes and warming at higher latitudes. However, after the onset, the existing circulation pattern gets dampened, resulted in a weaker latitudinal temperature structure. We saw that mean temperatures rose by about 20 K for the same local time after the onset of the dust storm. Our 3‐D Mars General Ionosphere Thermosphere Model calculations were able to reproduce the temperatures during the predust and early dust storm but failed to fully capture the temperature trend during the growth phase of the PEDE of 2018.

Effect of the 2018 Martian Global Dust Storm on the CO2 Density in the Lower Nightside Thermosphere Observed From MAVEN/IUVS Lyman‐Alpha Absorption

“…The uncertainty on the mean value is 0.5 km for both periods. Orbit 7182 occurred on 8 of June 2018 corresponding to the time where the increase of the dayside CO 2 density at 150 km was observed from the navigation camera (NAVCAM) of MAVEN (Bougher et al, ) and IUVS dayglow emissions (Jain et al, ). This increase is associated with the heating of the lower atmosphere by the GDS.…”

“…MAVEN accelerometers detected an enhancement in dayside CO 2 density at 150 km by a factor ~2 (Zurek et al, ) in agreement with the density variations observed by the NAVCAM and NGIMS instruments (Elrod et al, ; Bougher et al, ). From dayglow observations, IUVS observed an increase in the altitude of peak brightness of 5 to 8 km (Jain et al, ). This variability is in agreement with the derived variability measured at the nightside for the observations presented in this study.…”

“…This method was shown to be less accurate than the stellar/solar occultation method because it is based on only one wavelength instead of the full UV spectral range for occultations, yet it has the advantage of simplicity due to requiring fewer constraints on pointing, and portability to any latitudes, longitudes, and local time at nightside compared with terminator‐limited solar occultations. In June 2018, an intense global dust storm (GDS) surrounded Mars lasting a few months, heating the lower atmosphere (Kass et al, ) and led to an expansion of the Martian atmosphere by few kilometers at thermospheric altitudes (Bougher et al, ; see also Jain et al, , and Elrod et al, ). Since Lyman‐α absorption occurs in the lower thermosphere, an increase of CO 2 density at a given altitude during the GDS would be expected to increase the altitude of Lyman‐α absorption by CO 2 .…”

Enhanced Densities in the Martian Thermosphere Associated With the 2018 Planet‐Encircling Dust Event: Results From MENCA/MOM and NGIMS/MAVEN

“…Journal of Geophysical Research: Planets lation pattern and neutral densities on the dawnside (Elrod et al, 2020;Jain et al, 2020). In addition, it was reported that the local dust storms can also affect the Martian thermosphere (Liu et al, 2018;Withers & Pratt, 2013).…”

“…The coupling between the two regions takes place primarily through the radiative heating of the dust aerosols. The resulting heating and expansion of the Mars atmosphere and subsequent modifications to atmospheric circulation drive the changes in the upper atmosphere (e.g., Bell et al, 2007; Bougher et al, 2006; Elrod et al, 2020; González‐Galindo et al, 2015; Jain et al, 2020). Although the upper atmospheric changes are observed during all dust storms, they are prominent during the planet‐encircling dust events (PEDEs), such as the one occurred in 2018 (PEDE‐2018, Elrod et al, 2020; Jain et al, 2020).…”