Diurnal and Seasonal Variations of Aerosol Optical Depth Observed by MEDA/TIRS at Jezero Crater, Mars. Issue 1 (21st January 2023)

• Record Type: Journal Article
• Authors: Smith, Michael D.; Martínez, Germán M.; Sebastián, Eduardo; Lemmon, Mark T.; Wolff, Michael J.; Apéstigue, Victor; Arruego, Ignacio; Toledo, Daniel; Viúdez‐Moreiras, Daniel; Rodriguez‐Manfredi, Jose Antonio; Juarez, Manuel de la Torre
• Is Part Of: Journal of geophysical research. Volume 128:Issue 1(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-21
• Subjects: Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2022JE007560
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: The two upward‐looking Thermal InfraRed Sensor (TIRS) channels from the Mars Environmental Dynamics Analyzer (MEDA) instrument suite on board the Perseverance rover enable the retrieval of total aerosol optical depth (dust plus water ice cloud) above the rover for all observations when TIRS is taken. Because TIRS observes at thermal infrared wavelengths, the retrievals are possible during both the day and night and thus, they provide an excellent way to monitor both the diurnal and seasonal variations of aerosols above Jezero Crater. A retrieval algorithm has been developed for this purpose and here, we describe that algorithm along with our results for the first 400 sols of the Perseverance mission covering nearly the entire aphelion season as well as a regional dust storm and the beginning of the perihelion season. We find systematic diurnal variations in aerosol optical depth that can be associated with dust and water ice clouds as well as a clear change from a cloud‐filled aphelion season to a perihelion season where dust is the dominant aerosol. A comparison of retrieved optical depths between TIRS and the SkyCam camera that is also part of MEDA indicates evidence of possible diurnal variations in cloud height or particle size. Plain Language Summary: Observations made by the Thermal InfraRed Sensor (TIRS) instrument on the Perseverance rover enable the amount of airborne dust and clouds above the rover to be determined. The TIRS instrument observes thermal infrared radiation so it can observe the dust and clouds both during the day and night. Here, we present results for the first 13 months of observations by TIRS. These results show that the dust and clouds vary as a function of season on Mars and as a function of the time of day. At the beginning of the period of time studied here, there were more clouds than dust, and the clouds were maximum just before dawn and just after dusk. Later in the season, dust became the dominant aerosol, with the diurnal maximum near midday. Key Points: The Thermal InfraRed Sensor (TIRS) upward‐looking sensors enable the retrieval of total aerosol optical depth during both day and night Aerosol optical depth shows clear diurnal and seasonal trends. Diurnal maximum opacity is near dawn for clouds and near noon for dust TIRS retrievals of aerosol optical depth can detail the complex time history of rapidly changing events such as dust storms