Observations of Atmospheric Tides in the Middle and Upper Atmosphere of Mars From MAVEN and MRO

Abstract

Variability in the Martian upper atmosphere is strongly linked to the lower atmosphere and much of it can be attributed to vertical wave propagation. Atmospheric tides in particular are a well‐known phenomenon in the Martian atmosphere that play a key role in the transport of energy as they propagate to higher altitudes. Previous theoretical predictions and observations suggest that tides producing wavenumber‐2 and wavenumber‐3 patterns are strongest in a fixed local time at high altitudes, however, the energy they carry and the region of deposition are not well characterized. Given the availability of atmospheric observations from several spacecraft at the same time, in this paper, the nature and behavior of tides are studied concurrently at several altitudes. Here, six intervals are identified focused at fixed low latitudes utilizing simultaneous observations of the middle and upper atmosphere from in situ and remote sensing instruments on different spacecraft. In the middle atmosphere, strong wavenumber‐2 signatures are identified in the intervals north of the equator whereas, in the south, wavenumber‐3 signatures are strongest. Wave signatures observed in the upper atmosphere seem to be dominated by a mix of wavenumbers‐2 and ‐3. Seasonal variation is observed in the northern intervals, with very little interannual variability in all intervals considered. Estimates of energy based on dominant wavenumber amplitude suggest that most of the energy dissipates below ∼90 km. Furthermore, model sampled output captures the dominant wavenumbers observed in the middle atmosphere as well as the energy dissipation characteristics.

Atmospheric Tides at Low Latitudes in the Martian Upper Atmosphere Observed by MAVEN IUVS

“…Although recent studies have noted the deficiency of MCD at higher altitudes, which indicates the possible limitation of MCD predictions, for example, Kumar et al. (2022) showed that MCD results agree better with observations at low altitudes than at high altitudes, we compare with MCD results at low latitudes and 172 km in this study. For latitude range from −30° to 30°, the latitude‐Ls distribution of MCD relative density perturbations of DE2 at 172 km (seen in Figure 11 of Forbes et al.…”

“…Forbes et al ( 2020) compared the latitude-Ls temperature structures of MCS measurements and MCD results at 76 km and showed good agreement between them. Although recent studies have noted the deficiency of MCD at higher altitudes, which indicates the possible limitation of MCD predictions, for example, Kumar et al (2022) showed that MCD results agree better with observations at low altitudes than at high altitudes, we compare with MCD results at low latitudes and 172 km in this study. For latitude range from −30° to 30°, the latitude-Ls distribution of MCD relative density perturbations of DE2 at 172 km (seen in Figure 11 of Forbes et al (2020)) shows two prominent peaks between Ls range from 0° to 60° and 60° to 240° (hereafter DE2 major peaks).…”

Longitudinal Variations of Mars Thermosphere CO2, Ar, N2, and O Densities From MAVEN: Dependencies on Species Mass, Solar Flux, and Local Time

“…One of the signature features of Mars' thermosphere density is its longitudinal variability, which was first characterized within the 90-130 km height region by accelerometer measurements made during Mars Global Surveyor (MGS), Mars Odyssey, and Mars Reconnaissance Orbiter aerobraking operations (e.g., Angelats i Coll et al, 2004;Forbes & Hagan, 2000;Forbes et al, 2004;Joshi et al, 2000;Moudden & Forbes, 2015;Wang et al, 2006;Wilson, 2002;Withers, 2006;Withers et al, 2003), and more recently in connection with ExoMars Trace Gas Orbiter (TGO; Forbes et al, 2021). Similar depictions and analyses now exist for the ∼170-200 km region based on Neutral Gas and Ion Mass Spectrometer (NGIMS; Benna et al, 2015;Mahaffy et al, 2015) measurements (e.g., England et al, 2016;Fang et al, 2021;Kumar et al, 2022;Leelavathi et al, 2023;G. Liu et al, 2017) and ultraviolet imager (e.g., England et al, 2016;Kumar et al, 2022;Lo et al, 2015;Medvedev et al, 2016) measurements on the Mars Atmosphere and Volatile Evolution (MAVEN) mission (Jakosky et al, 2015).…”

Atmospheric Tides in the Middle and Upper Atmosphere of Mars at Northern High Latitudes: A Comparison of MAVEN‐EUVM and MRO‐MCS Observations With Model Results

“…The Mars Climate Database (MCD) version 6.1 and related software are publicly available at http://www-mars.lmd.jussieu.fr (Forget et al, 1999;Millour et al, 2017). The data products associated with this manuscript are derived from the data sets cited above and are archived in the Virginia Tech data repository that is in accordance with AGU's FAIR data policy (Kumar, 2023).…”