The vertical distribution of Martian aerosol particle size

Guzewich, Scott D.; Smith, M. D.; Wolff, Michael

doi:10.1002/2014je004704

Cited by 47 publications

(63 citation statements)

References 35 publications

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“…In this work, we present the seasonal evolution and variability of the vertical distribution of Martian water ice cloud particle size (specifically, effective radius [r eff ]) as observed by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) in limb‐scanning mode. This work extends the analysis presented by Guzewich et al (). These observations represent an important metric to evaluate the performance of Mars GCM microphysical modules and guide their improvement while also providing a window into Martian atmospheric aerosol interactions and processes.…”

Section: Introductionsupporting

confidence: 89%

“…The seasonal evolution of water ice cloud particle size in the polar regions (50–90° in each hemisphere) is more complicated. Guzewich et al () found that the polar hood clouds had roughly uniform particle sizes of 1.5 μm. Our more complete seasonal record shows that the end of the polar hood cloud season in the northern hemisphere (L s = 330–30°) does indeed exhibit fairly uniform ice particle size with altitude near 1.5 μm, but the remainder of the observable year exhibits different behavior.…”

Section: Resultsmentioning

confidence: 99%

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Seasonal Variation in Martian Water Ice Cloud Particle Size

Guzewich

Smith

2019

JGR Planets

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We employ the complete record of Mars limb‐viewing observations by the Compact Reconnaissance Imaging Spectrometer for Mars, totaling 922 successful retrievals, to chart the seasonal variation in water ice cloud particle size. Low‐latitude clouds exhibit particle size sorting with altitude at all seasons, with particles ranging from >3.0 μm in effective radius to 1.0–1.5 μm. However, at a given altitude, the ice particle size often varies through the year. Ice particle sizes in the tropics follow a different seasonal cycle than ice mixing ratio. North polar clouds have a complex seasonal cycle, with a sloped size profile with altitude as the polar hood cloud forms in early fall trending to a roughly uniform 1.5‐μm profile by the end of winter. These data are an important metric to validate and improve general circulation model microphysical routines and to better understand how Martian water ice clouds influence the atmospheric radiative budget.

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Section: Introductionsupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Seasonal Variation in Martian Water Ice Cloud Particle Size

Guzewich

Smith

2019

JGR Planets

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“…This is consistent with the observations of “detached dust layers” observed by MCS [ Heavens et al ., ] and TES [cf. Guzewich et al ., ], which represent an elevated maximum in the dust profile at this altitude. The concentrations of dust aerosols of size 3 µm are nearly zero at all altitudes during the dust storms.…”

Section: Resultsmentioning

confidence: 99%

“…Heavens et al ., ; cf. Guzewich et al ., ]. The dust profiles are calculated from the following equation

n ((),, r, z) ~ k \cdot n_{s} \cdot n ((), r) \cdot A ((), z)

where n ( r ) is the density distribution of aerosol particles of radius r , n s is observed dust concentration at the surface of Mars, the constant

k = 1 true/ ((), \int_{0}^{\infty} n (r) d r)

is obtained by integrating n ( r ) from r to r + d r , and A ( z ) is a parameterized scheme at altitude z as given below:

A ((), z) = ([], 1 - normalexp ([], prefix- \frac{{((), z - normalF normalH)}^{2}}{{F L}^{2}})) + B \cdot normalexp ([], prefix- \frac{{((), z - normalP normalH)}^{2}}{{P T}^{2}})

…”

Section: Seasonal and Vertical Variability Of Dustmentioning

confidence: 99%

Long‐term variability of dust optical depths on Mars during MY24–MY32 and their impact on subtropical lower ionosphere: Climatology, modeling, and observations

Sheel

Haider

2016

JGR Space Physics

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Dust optical depths (τ) for nine Martian years (MY24–MY32) in the subtropical region (25–35°S) have been used to classify distinct dust scenarios. These data are based on observations at 9.3 µm from the Mars Global Surveyor and Mars Odyssey missions and encompass the regional dust storms which occur every year around solar longitude (Ls) ~ 220° and the two major dust storms of MY25 and MY28. Constrained by these observations and the Mars Climate Sounder observations of detached dust layers, we estimate altitude profiles of dust concentrations. We discuss the characteristics of dust aerosol particles of different size between 0.2 and 3.0 µm by assuming a modified gamma distribution. We then use a comprehensive ion‐dust model to calculate ion densities and conductivities in the lower ionosphere of Mars in the absence of dust storm at τ = 0.1 and Ls = 150° and for three dust storm periods viz., (1) major dust storm at τ = 1.7 and Ls = 210°, (2) major dust storm at τ = 1.2 and Ls = 280°, and (3) regional dust storm at τ = 0.5 and Ls = 220°. The model with 12 neutral species considers galactic cosmic rays as a source of ionization. Results show that the density of the dominant hydrated cluster ions and the electrical conductivity are reduced by an order of magnitude near the surface for a few months until the dust storm settles down to its normal condition.

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“…The global nature of this phenomenon and the clear global solsticial pause at L s = 90-110° suggests that the mechanism suppressing dust lifting near solstice is not relegated to the winter polar region, nor is it solely related to the weakened eddy activity near winter solstice. Given that 1-1.5 µm dust particles [Guzewich et al, 2014] settle out of the atmosphere on timescales of days to weeks [Pollack et al, 1979;Kahre et al, 2008], the previously identified pause in storm-scale lifting during these time periods should have a noticeable effect on the global dust opacity unless the majority of lifting occurs at significantly different times or scales.…”

Section: Dust Storm Climatologymentioning

confidence: 99%