The diverse meteorology of Jezero crater over the first 250 sols of Perseverance on Mars

Abstract

NASA’s Perseverance rover’s Mars Environmental Dynamics Analyzer is collecting data at Jezero crater, characterizing the physical processes in the lowest layer of the Martian atmosphere. Here we present measurements from the instrument’s first 250 sols of operation, revealing a spatially and temporally variable meteorology at Jezero. We find that temperature measurements at four heights capture the response of the atmospheric surface layer to multiple phenomena. We observe the transition from a stable night-time thermal inversion to a daytime, highly turbulent convective regime, with large vertical thermal gradients. Measurement of multiple daily optical depths suggests aerosol concentrations are higher in the morning than in the afternoon. Measured wind patterns are driven mainly by local topography, with a small contribution from regional winds. Daily and seasonal variability of relative humidity shows a complex hydrologic cycle. These observations suggest that changes in some local surface properties, such as surface albedo and thermal inertia, play an influential role. On a larger scale, surface pressure measurements show typical signatures of gravity waves and baroclinic eddies in a part of the seasonal cycle previously characterized as low wave activity. These observations, both combined and simultaneous, unveil the diversity of processes driving change on today’s Martian surface at Jezero crater.

Convective Vortices and Dust Devils Detected and Characterized by Mars 2020

“…The dust in this event resulted in a decrease of the RDS Top 7 signal of 13%, with additional counterparts in RDS lateral sensors (not shown here). This corresponds to an increase of the optical depth of Δ τ = 0.14, which can be compared with values of optical depths at Jezero over that period of 0.4–0.5 (Rodriguez‐Manfredi et al., 2023). MEDA measured winds of 18 ms −1 distributed in two peaks coincident in time with half the maximum pressure drop.…”

“…In the LES, distant and long‐duration vortices are detected because of the clean pressure signal and the regular background winds imposed in the model. However, in the MEDA pressure data at Jezero, a measurement noise of 0.1 Pa combined with turbulent fluctuations in pressure (Sánchez‐Lavega et al., 2022), variations in wind speed and direction (Rodriguez‐Manfredi et al., 2023; Viúdez‐Moreiras et al., 2022) make detections of distant events more difficult to detect. Additional factors, such as the variations in spatial scales of a few meters of terrain roughness, inclination, thermal inertia, and albedo might also contribute to produce a more turbulent atmosphere than the one that can be simulated by the LES.…”

“…MEDA has found out strong variations of the TI of the terrain at spatial scales smaller than those sampled from orbit. TI with MEDA is measured from a combination of TIRS and RDS data (Martínez et al., 2023; Rodriguez‐Manfredi et al., 2023) resulting in values of TI that range from 180 to 610 Jm −2 K −1 s −1/2 (TI units hereafter). These values are comparable to those obtained from orbit by the THEMIS instrument (Fergason et al., 2006) on the Mars Odyssey orbiter.…”

“…MEDA measurements in Jezero show that variations in the values of TI over the rover's traverse correlate with strong variations in the vertical thermal gradient of the atmospheric surface layer (Munguira et al., 2023; Rodriguez‐Manfredi et al., 2023). This is the expected behavior in Mars, because terrains with low values of TI favor higher near‐noon surface temperatures and higher vertical thermal gradients, which is a key element in producing convective vortices (Rennó et al., 1998).…”

“…The Radiation and Dust Sensors (RDSs) on MEDA are a set of photodiodes oriented at different directions including a panchromatic sensor pointing to the vertical (RDS Top 7) with a 90° Field of View (Apestigue et al., 2022). In addition, MEDA measures the ground and air temperatures at different altitudes using the Thermal InfraRed Sensors (TIRSs) and Air Temperature Sensors (ATSs) packages (Munguira et al., 2023; Rodriguez‐Manfredi et al., 2021, 2023), therefore, obtaining the near surface temperature lapse rate, which is a key element in determining the frequency, intensity, horizontal size, and vertical extension of the vortices (Ordóñez‐Etxeberria et al., 2020; Rennó et al., 1998; Ryan, 1972; Spiga et al., 2021). Thus, multi‐sensorial investigations of convective vortices and DDs, and the properties of the environment in which they develop are possible with MEDA.…”