Open AccessMartian ice cloud distribution obtained from SPICAM nadir UV measurements
Author(s) -
Mateshvili Nina,
Fussen Didier,
Vanhellemont Filip,
Bingen Christine,
Dodion Jan,
Montmessin Franck,
Perrier Severine,
Dimarellis Emmanuel,
Bertaux JeanLoup
Publication year - 2007
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006je002827
Subject(s) - martian , nadir , atmosphere of mars , albedo (alchemy) , water vapor , mars exploration program , environmental science , cloud albedo , atmospheric sciences , polar , atmosphere (unit) , ice cloud , astrobiology , cloud computing , geology , meteorology , cloud cover , physics , astronomy , satellite , art , performance art , computer science , art history , operating system
The Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument on board Mars Express has successfully performed one Martian year of measurements. Nadir UV (200–310 nm) measurements allowed it to build maps of ice cloud optical depth distribution for all seasons. The development and decay of the aphelion cloud belt (ACB) and polar hoods were observed. The characteristic values of the cloud optical thickness were 0.1–0.3 at the early stage of the ACB formation in the solar longitude range L s = 20–60°. After L s = 93°, the well‐developed ACB showed cloud optical thicknesses varying between 0.3 and 0.8. The ACB quickly decayed after L s = 140°. Both polar hoods were observed during their development and decay stages, showing cloud optical thicknesses of about 0.35. The north polar hood started to develop at L s = 160° and the south one at L s = 330°. Estimates of water content in the ice clouds gave values of 0.35–1.8 gm −2 for ACB and 0.4 gm −2 for the polar hoods. A comparison with water vapor abundance showed that only a small fraction (10–20% for ACB and 30% for the polar hoods) of total water content in the atmosphere was accumulated in clouds. The Martian surface albedo at the wavelength 300 nm appeared very low (0.004–0.018) and exhibited anticorrelation with the visual albedo consistent with optical properties of iron oxides abundant in Martian soils. The investigation of a regional dust storm allowed the estimation of dust optical parameters at the wavelength 300 nm (asymmetry factor g d = 0.8 and single scattering albedo σ d = 0.6).