Ter-diurnal Thermal Tide on Mars

• DOI: 10.5194/epsc2024-36
• Publication Date: 2024-07-03T11:09:04Z
• Authors: Joonas Leino; Ari-Matti Harri; John Wilson; Don Banfield; Mark Lemmon; Mark Paton; Jose Rodríguez-Ma...; Hannu Savijärvi
• Keywords: Diurnal cycle

IntroductionCyclic absorption of solar radiation generates oscillations in atmospheric fields. These are called or thermal tides, which furthermore modified by topography, surface properties, and absorber concentration. This leads to a complex mix sun-synchronous non tides that propagate around the planet eastward westward. A major aspect study is obtain some global insight into Martian ter-diurnal seen at very small collection lander sites using Mars Climate Database (MCD) General Circulation Model (GCM). Observations MethodsHere we used hourly binned pressure observations Science Laboratory (MSL), InSight, Viking Lander (VL) 1, VL2 calculate harmonic components with Fast Fourier Transform (FFT) for each location. window three sols was get least one observation hour. The value averaged case multiple per Amplitudes phases were then calculated middle sol three-sol window. analysis performed station sliding over all data available platform.For MCD GCM data, similar approach except one-sol fields allow mapping evolving tide results and, further, decomposing these constituent westward propagating components. That done taking 2D FFT (in time longitudes) diurnal Moreover, special simulations without effect radiative heating water ice clouds provided LMD team. ResultsMSL InSight showed seasonal cycles highest amplitudes about Ls 60◦ , 130◦ 320◦ (Figure 1) . latest amplitude peak corresponds ”C” dust storm also visible semi-diurnal tidal amplitudes. However, during ”A” (at 230◦) neither platforms detected spikes. Observed VL1 seem be lacking clear structure, but quite repeatable pattern as MSL first half year. In addition, storms MY 12 (1977b) 15 clearly amplitude. did not show response 1977a planet-encircling storm. 34 demonstrating mission now.Figure 1: Ter-diurnal (normalized mean pressure, %) from MSL, VL1, well function season (Ls). MSL well, values between 05-07 LTST most year 08-10 60◦-120◦ 2). Phases observed Landers start predicted good agreement observations, MSL.Figure 2: Same Figure 1 (LTST). Overall, calculations on underestimate throughout year, especially dusty season. Globally, weakest equinoxes, while strongest ones summertime both hemispheres wavenumber 6 longitude northern hemisphere summer (Ls 90◦, 3). During this time, model suggest two prominent modes (TW3) an TE3 tide. meridional structure 4) mode characteristic resonantly-enhanced Kelvin wave, uniform latitude structure.Figure 3: Global normalized 0◦, 180◦, 270◦. Figure 4: (TW) (TE) zonal 1–4 season. Additional active peaks equator much less radiatively 5). delay advance phase 2), patterns indicate has wave. because MSL/InSight separated 180 degrees longitude, therefore deviation due wave would 3 locations, data. Interaction variations topography properties (thermal inertia albedo) may generate mode. By contrast, TW3 stronger away present longer fraction (Figures 4 component result direct forcing nonlinear interaction tides. Figure 5: Seasonal evolution (left panel) (right simulation. Dust column opacity contours shown field cloud (limited tropics) field. Based investigation, it seems reasonable infer cycle near equator, strongly influenced clouds. Nonetheless, typically lower than tides. Definitely more modeling studies needed understand behavior mechanisms important tide. ReferenceJoonas Leino, Ari-Matti Harri, John Wilson, et al. Atmospheric Tide Mars. ESS Open Archive April 26, 2024. DOI: 10.22541/essoar.171415900.05448468/v