Large Dust Aerosol Sizes Seen During the 2018 Martian Global Dust Event by the Curiosity Rover

Lemmon, M. T.; Guzewich, Scott D.; McConnochie, T. H.; Vicente‐Retortillo, Á.; Martínez, G.; Smith, M. D.; Bell, James F.; Wellington, Danika; Jacob, Samantha

doi:10.1029/2019gl084407

Cited by 71 publications

(84 citation statements)

References 34 publications

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“…One possibility is that these particles are not primarily composed of water ice but could host a relatively large dusty core. Incidentally, large dust particles have been reported from the surface during this GDS, (Lemmon et al, ), which could play a role as condensation nuclei for the water ice. Clancy et al () indeed observed during a previous GDS (2001) that large dust particles can propagate to high altitude (sizes between 1 and 2

normalμ

m above 70 km).…”

Section: Resultsmentioning

confidence: 87%

Martian Water Ice Clouds During the 2018 Global Dust Storm as Observed by the ACS‐MIR Channel Onboard the Trace Gas Orbiter

et al. 2020

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The Atmospheric Chemistry Suite (ACS) instrument onboard the ExoMars Trace Gas Orbiter (TGO) European Space Agency‐Roscosmos mission began science operations in March 2018. ACS Mid‐InfraRed (MIR) channel notably provides solar occultation observations of the Martian atmosphere in the 2.3‐ to 4.2‐ normalμ m spectral range. Here, we use these observations to characterize water ice clouds before and during the MY 34 Global Dust Storm (GDS). We developed a method to detect water ice clouds with mean particle size ≤ 2 normalμ m and applied it to observations gathered between Ls=165∘ and Ls=243∘. We observe a shift in water ice cloud maximum altitudes from about 60 km before the GDS to above 90 km during the storm. These very high altitude, small‐sized ( reff≤0.3.3emnormalμ m) water ice clouds are more frequent during MY 34 compared to non‐GDS years at the same season. Particle size frequently decreases with altitude, both locally within a given profile and globally in the whole data set. We observe that the maximum altitude at which a given size is observed can increase during the GDS by several tens of kilometers for certain sizes. We notably notice some large water ice particles ( reff≥1.5.3emnormalμ m) at surprisingly high altitudes during the GDS (50–70 km). These results suggest that GDS can significantly impact the formation and properties of high‐altitude water ice clouds as compared to the usual perihelion dust activity.

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normalμ

m above 70 km).…”

Section: Resultsmentioning

confidence: 87%

Martian Water Ice Clouds During the 2018 Global Dust Storm as Observed by the ACS‐MIR Channel Onboard the Trace Gas Orbiter

et al. 2020

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“…(2010), who detected particles of up to 2 µm during the 2001 GDS (MY 25). The observations of the 2018 GDS from the surface by the Curiosity Rover yielded > 4 μm particles (Lemmon et al., 2019).…”

Section: Summary and Discussionmentioning

confidence: 99%

Properties of Water Ice and Dust Particles in the Atmosphere of Mars During the 2018 Global Dust Storm as Inferred From the Atmospheric Chemistry Suite

et al. 2020

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Dust and water ice aerosols play a major role in the energy budget and circulation of the atmosphere of Mars and its climate. Dust affects the thermal structure and the dynamics of the atmosphere. Water ice clouds play an important part in the water cycle by altering the global transport of water vapor (Montmessin et al., 2004; Richardson & Wilson, 2002), by influencing the Martian climate radiatively (Madeleine et al., 2012; Wilson et al., 2008), and by changing the dust distribution through the scavenging of dust aerosols' particles due to the condensation of ice (Navarro et al., 2014; Pearl et al. 2001). Information on the aerosols physical properties is needed for a better understanding and modeling of Martian climate (

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“…In this study, we have avoided images taken during these higher opacity periods where possible. High opacities correspond to elevated optical depth (tau) values, as reported in Table S2 (Guzewich et al, 2019;Lemmon et al, 2019). Notable exceptions include the Voyageurs drill site (Sols 2,110 and 2,113; Figures 5 and 11), which exhibits such strong spectral contrast that it is not significantly affected by the slightly elevated opacities at that time.…”

Section: Orbital Imagesmentioning

confidence: 92%

Diagenesis of Vera Rubin Ridge, Gale Crater, Mars, From Mastcam Multispectral Images

et al. 2020

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Images from the Mars Science Laboratory (MSL) mission of lacustrine sedimentary rocks of Vera Rubin ridge on "Mt. Sharp" in Gale crater, Mars, have shown stark color variations from red to purple to gray. These color differences crosscut stratigraphy and are likely due to diagenetic alteration of the sediments after deposition. However, the chemistry and timing of these fluid interactions is unclear. Determining how diagenetic processes may have modified chemical and mineralogical signatures of ancient Martian environments is critical for understanding the past habitability of Mars and achieving the goals of the MSL mission. Here we use visible/near-infrared spectra from Mastcam and ChemCam to determine the mineralogical origins of color variations in the ridge. Color variations are consistent with changes in spectral properties related to the crystallinity, grain size, and texture of hematite. Coarse-grained gray hematite spectrally dominates in the gray patches and is present in the purple areas, while nanophase and fine-grained red crystalline hematite are present and spectrally dominate in the red and purple areas. We hypothesize that these differences were caused by grain-size coarsening of hematite by diagenetic fluids, as observed in terrestrial analogs. In this model, early primary reddening by oxidizing fluids near the surface was followed during or after burial by bleaching to form the gray patches, possibly with limited secondary reddening after exhumation. Diagenetic alteration may have diminished the preservation of biosignatures and changed the composition of the sediments, making it more difficult to interpret how conditions evolved in the paleolake over time. Plain Language Summary Sedimentary rocks found in deserts on Earth often exhibit striking color differences from red and purple to white, which are caused by groundwater dissolving and reprecipitating iron oxides within the rocks. NASA's Mars Science Laboratory (MSL) mission has observed similar color differences on Mars within the sedimentary rocks of Vera Rubin ridge in Gale crater, which were laid down in an ancient lake. We use color images and spectral data from the Mastcam cameras on MSL to investigate the origin of these color differences and find that they are consistent with changes in iron oxides through the ridge. This variation in iron oxides suggests that groundwater flowed through and altered these rocks multiple times before and after they were buried by later sediments. The MSL mission has shown that habitable lake environments once existed in Gale crater, through detections of the building blocks of life, including organic molecules, and by showing that conditions that existed in the lake were clement for life. However, later alteration by groundwater may have diminished the preservation of organics and changed the composition of these rocks, making it more difficult to interpret the details of how conditions evolved in the lake over time.

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Large Dust Aerosol Sizes Seen During the 2018 Martian Global Dust Event by the Curiosity Rover

Cited by 71 publications

References 34 publications

Martian Water Ice Clouds During the 2018 Global Dust Storm as Observed by the ACS‐MIR Channel Onboard the Trace Gas Orbiter

Martian Water Ice Clouds During the 2018 Global Dust Storm as Observed by the ACS‐MIR Channel Onboard the Trace Gas Orbiter

Properties of Water Ice and Dust Particles in the Atmosphere of Mars During the 2018 Global Dust Storm as Inferred From the Atmospheric Chemistry Suite

Diagenesis of Vera Rubin Ridge, Gale Crater, Mars, From Mastcam Multispectral Images

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