Extreme Dust Devils at Jezero from Mars 2020 MEDA data

Dust devils are convective vortices that produce intense winds able to lift dust from the surface [1]. On the cold and tenuous Martian atmosphere, dust devils are more frequent than on Earth and are frequently observed from spacecraft imagery and surface missions. The frequency, activity and overall properties of dust devils at different Martian location follow a daily and seasonal cycle driven by the characteristics of the planetary boundary layer and the local terrain. Perseverance, the rover of the Mars 2020 mission, has observed intense dust devil activity in its landing site at the Jezero area and the surrounding locations explored by Perserverance ever since the start of the mission in Feb. 2021 [2, 3]. Currently, data from Perseverance include observations obtained over more than 1800 sols or nearly 3 Martian Years. Here we analyze in situ meteorological data obtained by the MEDA instrument onboard Perseverance. MEDA is a set of meteorological sensors that obtain high-cadence observations of atmospheric variables including among others atmospheric pressure and temperature [4, 5]. MEDA is also equipped with wind sensors that started to accumulate damage from impacts with dust grains after sol 313 [3], but continued to be operated pending a recalibration of the data after that sol. MEDA is also equipped with the Radiation and Dust Sensor (RDS) [6], a series of photodiodes oriented in several directions that identify the presence of dust devils from the increase or reduction of light produced by the aerosols in the moving dust devil [7]. All of these sensors, including the progressively damaged wind sensors acquire data with a cadence of 1 Hz [5], but can be operated separately to save power and data volume, implying that MEDA measurement sessions may not have wind data during part of the observations with other sensors.

Here we focus our attention on the properties of the most intense vortices observed by MEDA. The close passage of convective vortices are identified by the pressure drop recorded by the pressure sensor. Events with pressure drops larger than 5.0 Pa are extreme in their characteristics. They generally include warm cores up to 10 K warmer than the environment from MEDA’s Air Temperature Sensors, and contain large amounts of dust from the simultaneous observations with the RDS. These events correspond to the close passage of very intense dust devils of a scale much stronger than a previous case imaged while passing through Perseverance [8]. The geometry of the encounters with these dust devils, and the overall dust content of the vortices are investigated from the analysis of the light signals obtained by the different lateral and vertical sensors in the RDS. Because convective vortices are near cyclostrophic equilibrium, these intense pressure drops should also be accompanied by fast winds that should change in direction and intensity while the vortex approaches and separates from Perseverance. We here show that a new retrieval of wind data being tested by the MEDA team produces additional results about the geometry of the encounter that can be independently tested with the signals recorded by the RDS. We compare and present data simultaneously obtained by all MEDA sensors during the passage of the most intense vortices observed over 1800 sols. We show the observed and derived characteristics of record events in terms of their internal pressure drop, the wind intensity, the internal temperatures in the vortex and the amount of dust in the dust devil walls. We also show the seasonal and local terrain context for the emergence of these extremely intense dust devils.

 

REFERENCES

[1] Balme, M., and R. Greeley (2006), Dust devils on Earth and Mars, Rev. Geophys., 44, RG3003, doi:10.1029/2005RG000188.

[2] Newman, C. E., et al. (2022). The dynamic atmospheric and aeolian environment of Jezero crater, Mars. Science Advances, 8(21), eabn3783. https://doi.org/10.1126/sciadv.abn3783

[3] Hueso, R., et al. (2023). Convective vortices and dust devils detected and characterized by Mars 2020. Journal of Geophysical Research: Planets, 128, e2022JE007516. https://doi.org/10.1029/2022JE007516

[4] Rodriguez-Manfredi, J.A., et al. (2021) The Mars Environmental Dynamics Analyzer, MEDA. A Suite of Environmental Sensors for the Mars 2020 Mission. Space Sci Rev 217, 48. https://doi.org/10.1007/s11214-021-00816-9

[5] Rodriguez-Manfredi, J.A., et al. (2023). The diverse meteorology of Jezero crater over the first 250 sols of Perseverance on Mars. Nat. Geosci. 16, 19–28. https://doi.org/10.1038/s41561-022-01084-0

[6] Apestigue, V., et al. (2022). Radiation and Dust Sensor for Mars Environmental Dynamic Analyzer Onboard M2020 Rover. Sensors, 22(8), 2907. https://doi.org/10.3390/s22082907

[7] Toledo, D., et al. (2023). Dust devil frequency of occurrence and radiative effects at Jezero crater, Mars, as measured by MEDA Radiation and Dust Sensor (RDS). Journal of Geophysical Research: Planets, 128, e2022JE007494. https://doi.org/10.1029/2022JE007494

[8] Murdoch, N. et al. (2022). The sound of a Martian dust devil. Nat Commun. 13, 7505. https://doi.org/10.1038/s41467-022-35100-z