Valles Marineris cloud trails

• Published in: Journal of Geophysical Research. B. Solid Earth 2009-11, Vol.114 (E11), p.n/a
• Main Authors: Clancy, R. Todd, Wolff, Michael J., Cantor, Bruce A., Malin, Michael C., Michaels, Timothy I.
• Format: Article
• Language: English
• Subjects: Altitude; Atmosphere; Atmospheric sciences; Canyons; Chemistry; Clouds; Earth sciences; Earth, ocean, space; Exact sciences and technology; Mars; Optical analysis; Physics; Planetology; Planets; Water vapor
• ISSN: 0148-0227; 2169-9097; 2156-2202; 2169-9100
• DOI: 10.1029/2008JE003323

Distinctive cloud trails are identified in Mars Reconnaissance Orbiter Mars Color Imager (MARCI) images over specific locations associated with Valles Marineris and Noctis Labyrinthus and at perihelion solar longitudes (LS = 230°–260°). High‐contrast surface shadows are well defined, as cast from their eastern margins, supporting altitude and optical depth determinations. These relatively high altitude clouds (40–50 km) exhibit narrow latitudinal widths (25–75 km) in comparison to extended longitudinal dimensions (400–1000 km). MARCI multispectral imaging of cloud surface shadows in five wavelength channels (260, 320, 437, 546, and 653 nm) yields the wavelength dependence of cloud extinction optical depth, revealing a range of small cloud particle sizes (reff = 0.2–0.5 μm) and moderate cloud optical depths (0.03–0.10 visible and 0.1–0.2 ultraviolet). Local time and temporal sampling characteristics of MARCI cloud images indicate that these clouds develop very rapidly in afternoon hours (1300–1500 LT), reach their full longitudinal extents within