The meteo of Jezero crater as determined from MEDA observations and modeling: from validation to physical interpretation

Understanding the near-surface meteorology of Mars is essential for interpreting atmospheric processes, supporting robotic operations, and preparing future human exploration. The Mars 2020 Perseverance rover has provided an unprecedented meteorological record at Jezero crater through the Mars Environmental Dynamics Analyzer (MEDA) [1]. Prior to landing, mesoscale and global modeling studies provided predictions of the atmospheric behavior expected at the landing site, establishing a baseline for post-landing validation [2, 3]. This study represents a major step forward from that initial validation effort, moving beyond model–data comparison toward a physically consistent interpretation of the meteorological system at Jezero crater.

We present an updated and expanded comparison between MEDA observations and high-resolution Mars Regional Atmospheric Modeling System (MRAMS) simulations, incorporating full diurnal-cycle simulations every 30° of solar longitude (Ls) across two complete Martian years. This represents one of the highest temporal-frequency mesoscale modeling datasets ever produced at high resolution on Mars, with the innermost grid reaching approximately 330 m horizontal spacing. In addition to crater-scale analysis, we adopt a multiscale framework that explicitly connects the regional circulation of the Isidis basin with local processes inside Jezero crater. This approach allows us to investigate how large-scale forcing, crater topography, slope flows, and surface-atmosphere interactions jointly control the observed meteorological cycles at the rover location.

We compare MRAMS results with MEDA observations of pressure, air temperature, ground temperature, and horizontal winds. Among these variables, pressure emerges as a particularly robust validation metric. The model reproduces the shape, amplitude, and seasonal evolution of the diurnal pressure cycle with good fidelity after applying normalization techniques to account for large-scale biases. This strong agreement demonstrates that MRAMS captures the essential dynamical response of the atmosphere at both regional and crater scales, providing a solid foundation for interpreting more complex variables.

Air and ground temperature comparisons show that MRAMS successfully reproduces the general structure of the diurnal thermal cycle, including daytime heating and nighttime cooling, but discrepancies remain in amplitude and timing. These differences highlight the importance of local surface properties, including thermal inertia, albedo, and small-scale heterogeneity, which are not fully resolved in the orbital datasets used to initialize the model. Jezero crater exhibits significant geological diversity along the rover traverse, and the inability to resolve these variations likely contributes to the observed mismatches. Therefore, temperature acts as a key diagnostic of surface-atmosphere coupling and emphasizes the need for improved characterization of surface properties in mesoscale simulations.

The comparison of winds between MRAMS and MEDA reveals that the model captures many of the dominant atmospheric regimes observed at Jezero, including the strong diurnal organization of flows associated with slope winds, crater circulations, and regional forcing. In this study, the wind analysis is restricted to horizontal wind measurements from sols 15 to 313 (Ls ∼ 152°), as several wind sensor boards were damaged by wind-driven grain impacts around sols 313–315. Within this period, both model and observations show very low wind speeds immediately after sunset, following the collapse of daytime convective turbulence, followed by a nocturnal increase associated with the development of downslope and drainage flows driven by crater topography.

Despite this overall agreement, systematic discrepancies remain and constitute one of the most important scientific outcomes of this study. MRAMS tends to overestimate nocturnal wind speeds, particularly between approximately 01:00 local time and dawn. This behavior suggests that modeled downslope flows originating from the crater rim and surrounding terrain may penetrate too efficiently into the crater interior, or that the model overestimates momentum mixing under stable boundary-layer conditions. Differences in wind direction and in the timing of regime transitions further point to limitations in the representation of local slopes, surface roughness, unresolved obstacles, or the interaction between crater-scale and regional circulations. Importantly, these discrepancies are not treated as simple model errors but as key diagnostics of the underlying physics, providing insight into where improvements are needed in boundary-layer parameterizations, surface properties, and model resolution.

Taken together, pressure, temperature, and wind comparisons reveal a complementary picture in which each variable constrains different aspects of the system: pressure validates the large-scale and dynamical framework, temperature diagnoses surface-atmosphere thermal coupling and heterogeneity, and winds provide the most demanding test of the model’s ability to reproduce local and regional circulations. This multi-variable, multi-scale approach demonstrates that high-resolution mesoscale modeling can be used not only as a predictive tool but as a diagnostic framework for understanding Martian boundary-layer processes in complex terrain.

Overall, this study shows that the meteorology of Jezero crater is controlled by a complex interplay between regional circulation (particularly the influence of the Isidis basin), crater-scale topography, surface thermal contrasts, and boundary-layer evolution. The combination of MEDA observations and MRAMS simulations enables a physically consistent interpretation of these processes. While the agreement between model and observations supports the use of MRAMS to extend point measurements into a broader spatial context, the remaining discrepancies highlight key areas for future improvement. These results contribute to a deeper understanding of Martian near-surface meteorology and provide valuable insights for future mission planning, landing site characterization, and atmospheric modeling efforts on Mars.

References:

[1] Rodriguez-Manfredi, J. A., De la Torre Juárez, M., Alonso, A., Apéstigue, V., Arruego, I., Atienza, T., ... & MEDA team. (2021). The Mars Environmental Dynamics Analyzer, MEDA. A suite of environmental sensors for the Mars 2020 mission. Space science reviews, 217, 1-86.

[2] Pla-García, J., Rafkin, S. C., Martinez, G. M., Vicente-Retortillo, Á., Newman, C. E., Savijärvi, H., ... & Harri, A. M. (2020). Meteorological predictions for Mars 2020 Perseverance Rover landing site at Jezero crater. Space science reviews, 216(8), 148.

[3] Newman, C. E., de la Torre Juárez, M., Pla-García, J., Wilson, R. J., Lewis, S. R., Neary, L., ... & Rodriguez-Manfredi, J. A. (2021). Multi-model meteorological and aeolian predictions for Mars 2020 and the Jezero crater region. Space Science Reviews, 217, 1-68.