Dusty Deep Convection in the Mars Year 34 Planet‐Encircling Dust Event

Heavens, N. G.; Kass, D. M.; Shirley, James H.

doi:10.1029/2019je006110

Cited by 39 publications

(46 citation statements)

References 87 publications

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“…Journal of Geophysical Research: Planets transports dust at higher altitudes). These plumes are consistent with MCS observations of several dust convective events during the MY34 GDS (Heavens et al, 2019). In particular, the large plume shown on Figure 15 is consistent with the specific MCS observation of dust convective activity at similar times (L s~1 98°) and locations (near Tharsis).…”

Section: /2019je006122supporting

confidence: 88%

Simulation of the 2018 Global Dust Storm on Mars Using the NASA Ames Mars GCM: A Multitracer Approach

et al. 2020

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Global dust storms are the most thermodynamically significant dust events on Mars. The most recent of these events occurred in 2018. Although it was monitored by several spacecraft in orbit and on the surface, many questions remain regarding its onset, expansion and decay. Here, we model the 2018 event with the National Aeronautics and Space Administration (NASA) Ames Mars Global Climate Model in order to better understand the evolution of the storm. Our results highlight a mechanism for the expansion of the storm: the initial equatorial regional storm creates a zonal atmospheric temperature gradient causing strong equatorial eastward winds and thus rapid eastward transport of dust and subsequent lifting. The model shows rapid back and forth transfer of dust between western and eastern hemispheres reservoirs, which may also play an important role in the storm's development through teleconnections involving replenishment of surface dust. The model also shows that gigantic dust plumes occur during the storm's mature phase, injecting dust up to 80 km. Our analysis shows that their upward motion in the atmosphere is due to the ascending branches of Hadley cells, whose intensity is reinforced during the storm with increasing dustiness. We show that the global atmospheric warming during the storm cause vapor and water ice clouds to migrate to higher altitudes, in line with recent observations. Finally, we find that the choice of effective radius for the lifted dust particle size distribution impacts the intensity of the Hadley circulation and could explain some of the differences obtained between model results and observations.

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Section: /2019je006122supporting

confidence: 88%

Simulation of the 2018 Global Dust Storm on Mars Using the NASA Ames Mars GCM: A Multitracer Approach

et al. 2020

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“…Spacecraft observations provide a wealth of information on the inception and development of the 2018 GDS (Guzewich et al, 2018;cf. Kass et al, 2019;Smith, 2019;Heavens et al, 2019;Shirley, Kleinböhl, et al, 2019;Lemmon et al, 2019;Kleinböhl, et al, 2020). As with prior storms, the locations of initial dust lifting and the spatial and temporal development of lifted dust are well characterized by spacecraft visual imaging, nadir sounding, and limb sounding.…”

Section: Triggering Of the Martian Global-scale Dust Storm Of 2018mentioning

confidence: 99%

Orbit‐Spin Coupling and the Triggering of the Martian Planet‐Encircling Dust Storm of 2018

et al. 2020

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The Martian global dust storm (GDS) of 2018 began soon after the southern spring equinox, which is quite early in the dust storm season. The origins of early‐season GDS, including those of 1977, 2001, and now 2018, have been mysterious, as atmospheric dynamical investigations and numerical modeling experiments have been unable to explain or reproduce the timing of these events. We employ a newly expanded catalog of historic Martian GDS for our investigation, which includes 2018 and the telescopically observed equinoctial dust storms of 1877 and 1909. All of the GDS of this catalog took place either (1) when orbit‐spin coupling torques on the Martian atmosphere were near peak values or (2) near times when the orbit‐spin coupling torques were changing most rapidly. The second category, here termed “Mode 2,” includes all six of the equinoctial GDS of the historic record, including 2018. Recognition of the existence of two triggering modes for GDS occurrence leads to a significant improvement in temporal resolution for both hindcasting and forecasting. Orbit‐spin coupling now provides explanations for the late‐season inception dates of the 1924 and 1973 storms, as well as for the equinoctial events. We provide conditional forecasts, with sub‐seasonal time resolution, for GDS occurrence and non‐occurrence in Mars years 35 through 40. We introduce a detailed working hypothesis for the genesis of equinoctial GDS that may be validated through numerical modeling. The characteristic timescale for frictional damping of an intensified Martian Hadley circulation is estimated to be O(10) sols.

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“…The very rapid growth of the AC storm in latitude thus argues against a dominant role for this dust lofting mechanism during the period under investigation. DDC (Heavens, Kass, & Shirley, ; Heavens, Kass, Shirley, Piqueux, & Cantor, ; Rafkin, ), also fundamentally a mesoscale phenomenon, likewise does not plausibly account for the observed rapid lateral expansion of the AC storm. The DDC mechanism nonetheless appears to play a major role in high‐altitude dust lofting during later phases of the 2018 GDE (Heavens, Kass, & Shirley, ).…”

Section: Dust Lofting Mechanisms: Correspondence With Observationsmentioning

confidence: 99%

“…DDC (Heavens, Kass, & Shirley, ; Heavens, Kass, Shirley, Piqueux, & Cantor, ; Rafkin, ), also fundamentally a mesoscale phenomenon, likewise does not plausibly account for the observed rapid lateral expansion of the AC storm. The DDC mechanism nonetheless appears to play a major role in high‐altitude dust lofting during later phases of the 2018 GDE (Heavens, Kass, & Shirley, ). MCS observations subsequent to 10 June reveal numerous convective hot towers, with high dust mass mixing ratios, extending to altitudes ≥80 km above the surface.…”

Section: Dust Lofting Mechanisms: Correspondence With Observationsmentioning

confidence: 99%

“…Other candidate dust lofting hypotheses involve interactions between atmospheric radiative transfer and local‐scale circulations. The proposed mechanisms in this category include rocket dust storms (Spiga et al, ), the solar escalator effect (Daerden et al, ), and dusty deep convection (DDC) (Heavens, Kass, & Shirley, ; Heavens, Kass, Shirley, Piqueux, & Cantor, ; Rafkin, ). In the rocket dust storm mechanism, radiative heating drives rapid convective vertical transport of dust to altitudes from 30 to 40 km.…”

Section: Introductionmentioning

confidence: 99%

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Rapid Expansion and Evolution of a Regional Dust Storm in the Acidalia Corridor During the Initial Growth Phase of the Martian Global Dust Storm of 2018

Shirley

Kleinböhl

Kass

et al. 2020

Geophysical Research Letters

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A vigorous regional dust storm substantially altered both the global atmospheric thermal structure and the magnitude and spatial distribution of dust loading within the Mars atmosphere between 1 and 9 June 2018. We examine the development and decay of this storm in latitude, longitude, altitude, and time, employing observations by the Mars Climate Sounder on board the Mars Reconnaissance Orbiter. Dust layer top altitudes rose from seasonal-normal values of~40 to~70 km. Dust lofting to high altitudes was localized between 0°and~60°W longitude, and between 60°N and 60°S latitude. Intensification of paired meridional overturning circulation cells within the study area is confirmed by strong nighttime dynamical heating in higher latitudes of both hemispheres. By the end of this episode, significant dust loading was present at altitudes greater than 50 km above all longitudes on Mars, and other dust lifting centers had been activated.Plain Language Summary Why do some Martian dust storms, in some Mars years, expand to become global in scale, while the vast majority do not? We use infrared observations of the Mars atmosphere by the Mars Climate Sounder, on board the Mars Reconnaissance Orbiter spacecraft, to study this question. We examine the earliest days of the global dust storm of 2018, from 29 May through 9 June 2018. One key difference between regional and global dust storms is the altitude, within the atmosphere, to which dust is lofted during the storms. We show that dust was carried to much higher altitudes than normal during the first week of June, and that this major pulse of high-altitude dust lofting was localized between about 0°and 60°W longitude. These longitudes include the "Acidalia storm track." The circulation pattern, within this corridor, looks very much like a textbook Hadley circulation, where warm air rises rapidly above the equatorial latitudes, flowing both northward and southward, to later sink back toward the surface in middle latitudes. This circulation strengthened considerably during the earliest days of the global storm. These observations have important implications bearing on the mechanisms of Martian global dust storm occurrence.

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Dusty Deep Convection in the Mars Year 34 Planet‐Encircling Dust Event

Cited by 39 publications

References 87 publications

Simulation of the 2018 Global Dust Storm on Mars Using the NASA Ames Mars GCM: A Multitracer Approach

Simulation of the 2018 Global Dust Storm on Mars Using the NASA Ames Mars GCM: A Multitracer Approach

Orbit‐Spin Coupling and the Triggering of the Martian Planet‐Encircling Dust Storm of 2018

Rapid Expansion and Evolution of a Regional Dust Storm in the Acidalia Corridor During the Initial Growth Phase of the Martian Global Dust Storm of 2018

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