Classifying turbulence regimes in the Martian atmosphere at Jezero Crater, Mars

Atmospheric turbulence is defined by irregular fluctuations that develop in most flows, from small-scale near-surface breezes to planetary-scale circulation patterns. Its properties influence the dynamics of flight, design of structures, aeolian interactions between the atmosphere and surface, and the modeling of atmospheric processes. It has been studied most precisely on Earth, leading to models tailored accordingly to terrestrial conditions. Wind speed data collected by Perseverance’s Mars Environmental Dynamics Analyzer (MEDA) are used to determine the turbulence regime that can be resolved by the current equipment on Mars. We use a methodology based on universal spectral scaling, which allows estimates of the threshold scales that separate the energetic, inertial, and molecular dissipation regimes. Results indicate that the MEDA wind measurements on Mars can resolve turbulence scales that span the energetic regime and approach the inertial regime. Although the large-scale end of the inertial regime can be resolved, a 2 Hz sampling frequency, thus far the fastest sampling rate for direct wind sensor measurements on Mars, is not sufficient for covering the entire inertial subrange and resolving its smallest scales. The scales found with this method complement and are consistent with those estimated independently from stagnation pressure measurements, may explain the smallest size observed thus far for dust devils, and may contribute to why multiple reports have not found a consistent Kolmogorov-like spectral regime on Mars. One-Sentence Summary: Wind speed measurements made in Jezero crater resolve the bounds for the turbulence scales on both sides of the inertial subrange. These bounds set constraints on the sizes for coherent structures before they get dissipated by turbulence.