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Constraints on Mars Aphelion Cloud Belt phase function and ice crystal geometriesThis study constrains the lower bound of the scattering phase function of Martian water ice clouds (WICs) throughthe implementation of a new observation aboard the Mars Science Laboratory (MSL). The Phase Function SkySurvey (PFSS) was a multiple pointing all-sky observation taken with the navigation cameras (Navcam) aboardMSL. The PFSS was executed 35 times during the Aphelion Cloud Belt (ACB) season of Mars Year 34 over a solarlongitude range of Ls = 61:4 156:5. Twenty observations occurred in the morning hours between 06:00 and 09:30 LTST, and 15 runs occurred in the evening hours between 14:30 and 18:00 LTST, with an operationallyrequired 2.5 h gap on either side of local noon due the sun being located near zenith. The resultant WIC phasefunction was derived over an observed scattering angle range of 18.3-152.61, normalized, and compared with 9modeled phase functions: seven ice crystal habits and two Martian WIC phase functions currently being implementedin models. Through statistical chi-squared probability tests, the five most probable ice crystal geometriesobserved in the ACB WICs were aggregates, hexagonal solid columns, hollow columns, plates, and bullet rosetteswith p-values greater than or equal to 0.60, 0.57,0.56,0.56, and 0.55, respectively. Droxtals and spheres had pvaluesof 0.35, and 0.2, making them less probable components of Martian WICs, but still statistically possibleones. Having a better understanding of the ice crystal habit and phase function of Martian water ice cloudsdirectly benefits Martian climate models which currently assume spherical and cylindrical particles.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Cooper, Brittney
(York University Toronto, Ontario, Canada)
Moores, John
(York University Toronto, Ontario, Canada)
Ellison, Douglas J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Kloos, Jacob
(York University Toronto, Ontario, Canada)
Smith, Christina
(York University Toronto, Ontario, Canada)
Guzewich, Scott D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Campbell, Charissa
(York University Toronto, Ontario, Canada)
Date Acquired
April 11, 2019
Publication Date
April 1, 2019
Publication Information
Publication: Planetary and Space Science
Publisher: Elsevier
Volume: 168
ISSN: 0032-0633
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
Distribution Limits
Use by or on behalf of the US Gov. Permitted.
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