Modeling Baroclinic Pressure Oscillations in the Martian Atmosphere

Atmospheric pressure is a key indicator of weather patterns on both Earth and Mars. Variations in pressure can reveal the movement of air masses, the development of storms, and the behavior of large-scale atmospheric systems. One important type of such systems is the baroclinic wave, which forms in the presence of strong temperature gradients between the poles and the equator. These waves play a major role in redistributing heat and energy across a planet and are closely linked to storm activity. On Mars, baroclinic waves generate recurring pressure disturbances detectable by surface instruments. Leino et al. (2026) analyzed oscillations with periods of 2 to 10 sols across all available surface pressure observations. Here, we compare surface pressure oscillations derived from a General Circulation Model (GCM), specifically the Mars Planetary Climate Model (PCM), with the observations reported in Leino et al. (2026) using similar approach, and examine global pressure wave structures in both hemispheres.

Northern hemisphere midlatitude surface pressure waves in the PCM simulation intensify around Ls 170° in Mars Year (MY) 36. Eastward-propagating eddies with zonal wavenumber 2 dominate until Ls 225°, after which wavenumber 1 strengthens while overall amplitudes slightly weaken. After Ls 300°, amplitudes begin to intensify again, and the dominant structure alternates between wavenumbers 1-3.

Comparison with surface observations from Viking Lander 1 and 2 (VL1 and VL2), Perseverance, InSight, and the Mars Science Laboratory (MSL) shows partial agreement but also notable discrepancies. A major discrepancy is the absence of short-period (2-4 sol) wave peaks across all lander locations during Ls 220°-315°. However, some weaker background activity is still detected at the VL1 and VL2 sites. Observations clearly indicate a strong presence of these waves, including distinct peaks, during this period, whereas the PCM does not reproduce them. Instead, longer-period waves (5-8 sols) dominate in the model. The seasonal evolution of these waves is broadly consistent with observations, but their amplitudes are typically overestimated in the PCM.

Around Ls 330°-350°, the PCM produces a strong wave with a period of 2-3 sols. Elevated springtime amplitudes have also been observed at surface platforms during several MYs (Leino et al., 2026), although the observed pressure waves are generally weaker. In the PCM, this wave exhibit a midlatitude zonal wavenumber 3 structure and eastward propagation with a phase speed of approximately 15-20 m/s.

Despite similar latitudes, differences are found between VL1 and Perseverance: the springtime wavenumber 3 structure extends farther meridionally at VL1, while around Ls 270° the dominant wavenumber 1 structure shows a comparable meridional extent at both locations.

Southern hemisphere midlatitude waves are substantially weaker and develop around Ls 350°, with intermittent variability. Their structure is typically dominated by wavenumbers 2-3, with peak amplitudes at Ls 170°-210°, when northern hemisphere waves also begin to develop.

 

References

Leino, J., Harri, A.M., Wilson, R.J., Bertrand, T., Banfield, D., Mäkinen, T., Paton, M., Savijärvi, H., Martínez, G., Rodríguez-Manfredi, J.A., 2026. Baroclinic pressure oscillations in the martian atmosphere from surface observations. Icarus 456, 117138.