Nocturnal Turbulence at Jezero Crater as Determined From MEDA Measurements and Modeling

Abstract

Mars 2020 Mars Environmental Dynamics Analyzer (MEDA) instrument data acquired during half of a Martian year (Ls 13°–180°), and modeling efforts with the Mars Regional Atmospheric Modeling System (MRAMS) and the Mars Climate Database (MCD) enable the study of the seasonal evolution and variability of nocturnal atmospheric turbulence at Jezero crater. Nighttime conditions in Mars's Planetary Boundary Layer are highly stable because of strong radiative cooling that efficiently inhibits convection. However, MEDA nighttime observations of simultaneous rapid fluctuations in horizontal wind speed and air temperatures suggest the development of nighttime turbulence in Jezero crater. Mesoscale modeling with MRAMS also shows a similar pattern and enables us to investigate the origins of this turbulence and the mechanisms at play. As opposed to Gale crater, less evidence of turbulence from breaking mountain wave activity was found in Jezero during the period studied with MRAMS. On the contrary, the model suggests that nighttime turbulence at Jezero crater is explained by increasingly strong wind shear produced by the development of an atmospheric bore‐like disturbance at the nocturnal inversion interface. These atmospheric bores are produced by downslope winds from the west rim undercutting a strong low‐level jet aloft from ∼19:00 to 01:00 LTST and from ∼01:00 LTST to dawn when undercutting weak winds aloft. The enhanced wind shear leads to a reduction in the Richardson number and an onset of mechanical turbulence. Once the critical Richardson Number is reached (Ri ∼ <0.25), shear instabilities can mix warmer air aloft down to the surface.

Convective Vortices and Dust Devils Detected and Characterized by Mars 2020

“…Nighttime pressure drops can be driven by orographic mechanical turbulence at Gale crater (Ordonez‐Etxeberria et al., 2018), and by the interaction of a low‐level jet and weak stability in Elysium (Chatain et al., 2021). In Jezero, nighttime turbulence appears in different atmospheric fields (winds, pressure and temperature) and has the characteristics of a bore‐like disturbance (Pla‐Garcia et al., 2022) that could be the cause of the nighttime pressure drops not associated to the heat island effect.…”

One Martian Year of Near‐Surface Temperatures at Jezero From MEDA Measurements on Mars2020/Perseverance

“…De la Torre Juárez et al ( 2023) further analyzed the statistical properties of fluctuations of MEDA winds and temperatures on selected sols to find different turbulence regimes in the near surface atmosphere, and Munguira et al (2023) quantified the thermal oscillations over 400 sols as a proxy of the varying level of daytime near-surface convective activity at Jezero, finding a linear relation between temperature fluctuations and thermal gradients during daytime. An additional analysis by Pla-García et al (2023) concluded that topographic flows driving turbulence during nighttime also cause temperature fluctuations.…”