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. Issue 9 (25th April 2020)

• Record Type: Journal Article
• Authors: Shirley, J. H.; Kleinböhl, A.; Kass, D. M.; Steele, L. J.; Heavens, N. G.; Suzuki, S.; Piqueux, S.; Schofield, J. T.; McCleese, D. J.
• Is Part Of: Geophysical research letters. Volume 47:Issue 9(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-04-25
• Subjects: Mars -- Mars atmosphere -- Mars Climate Sounder -- MCS -- global dust storm -- orbit‐spin coupling; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL084317
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: 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. Key Points: We examine the development and decay of a vigorous regional dust storm during the initial growth phase of the 2018 global dust storm Rapid vertical expansion of dust clouds (to ~70‐km altitudes) was localized above the Acidalia storm track during this episode Strong localized descending branch adiabatic heating confirms strengthening of a regional‐scale Hadley circulation within the study area