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- Title
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.
- Authors
Kumar, Aishwarya; England, Scott L.; Liu, Guiping; Thiemann, Edward M. B.
- Abstract
Much of the variability in the Martian thermosphere can be attributed to vertically propagating atmospheric tides that are known to achieve significant amplitudes in this region. Concurrent observations from different altitudes have been used previously to discern the vertical propagation characteristics of tides but have primarily focused on low latitudes. The spectrum of tides and their vertical evolution are thereby less constrained at high latitudes. Few studies that have focused on high latitudes identified wavenumber‐3 structures which were interpreted to originate mainly from the non‐migrating tides SE1 and DE2. This paper presents the first analysis of MAVEN‐EUVM solar occultation observations to deduce atmospheric tides in the Martian thermosphere. These are compared to tides observed by MRO‐MCS in the middle atmosphere for six cases at high northern latitudes. To identify vertical propagation, wave signatures in the middle and upper atmosphere are compared and are found to be dominated by a mix of zonal wavenumbers‐2 and ‐3 in fixed local time. MCS observations show eastward propagating tides dominate, specifically highlighting SE1 near 76 km. Additionally, these observations indicate the presence of stationary planetary waves and terdiurnal tides. Mars Climate Database also indicates the presence of SE1, DE2, DE1, S0, TW1, and T0 tides. A change in the dominant wavenumber component with local time is seen, which is attributed to the presence of all three diurnal, semidiurnal and terdiurnal components at these latitudes. The significant decrease in the diurnal tide amplitude indicates the effect of zonal mean wind on vertical propagation. Plain Language Summary: Atmospheric tides are a kind of wave in the Martian atmosphere that can cause large oscillations in temperature, density, and pressure. Concurrent observations from different altitudes can determine how tides vary as they propagate into the upper atmosphere. Several previous studies have observed wave signatures from a range of heights but focused mainly on equatorial regions. Previous observations from near polar regions revealed strong tidal signatures, producing wave patterns with three peaks in the upper and middle atmosphere, attributed to a mix of waves with one and half a Mars day frequency. Here, using observations from two instruments that simultaneously measure the middle and upper atmosphere of Mars, dominant wave signatures at high latitudes are identified and how they change between these regions are examined. This study presents the first observations of atmospheric tides from new data derived from the extinction of solar radiation in the Martian upper atmosphere. Additionally, the observations are compared to a model, providing insight into how well the model captures the observations. A key finding is that the strongest wave component seen may vary with local time due to the presence of three different waves with one, half, and third of a Mars day frequency. Key Points: This study presents the first analysis of tides from solar occultation observations at MarsThe dominant wavenumber can change with local time due to the presence of tides with multiple periods at high latitudesDiurnal tides in the model diminish with altitude, suggesting the influence of mean winds on vertical propagation
- Subjects
ATMOSPHERIC tides; UPPER atmosphere; MARTIAN atmosphere; MIDDLE atmosphere; THERMOSPHERE; ROSSBY waves
- Publication
Journal of Geophysical Research. Planets, 2024, Vol 129, Issue 4, p1
- ISSN
2169-9097
- Publication type
Article
- DOI
10.1029/2023JE007887