Open AccessDust haze in Valles Marineris observed by HRSC and OMEGA on board Mars Express
Author(s) -
Inada A.,
GarciaComas M.,
Altieri F.,
Gwinner K.,
Poulet F.,
Bellucci G.,
Keller H. U.,
Markiewicz W. J.,
Richardson M. I.,
Hoekzema N.,
Neukum G.,
Bibring J.P.
Publication year - 2008
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 - 10.1029/2007je002893
Subject(s) - haze , mars exploration program , remote sensing , atmospheric radiative transfer codes , wavelength , environmental science , omega , scattering , aerosol , radiative transfer , geology , physics , optics , astronomy , meteorology , quantum mechanics
We present analysis of a bright haze observed inside Valles Marineris, which formed in mid northern spring. The data were collected by the High Resolution Stereo Camera (HRSC) and the imaging spectrometer, Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA), aboard Mars Express. This study provides a case example of the power of simultaneous multiple emission angle and hyperspectral imaging for study of aerosols and clouds in the Martian atmosphere. The haze appeared thinner after three days and disappeared in nine days. It was limited to a 2‐km layer at the bottom of the canyon. The color was redder than the underlying surface. The analysis of the OMEGA spectra indicates that this haze was composed of dust particles. The dust layer appeared brighter with the HRSC stereo channels than the nadir channel due to longer scattering paths. We have estimated the optical depth of the haze by fitting both HRSC and OMEGA data with radiative transfer calculations. The retrieval of the optical depth is very sensitive to the aerosol scattering model used and the reflectance of the surface. Applying an aerosol scattering model derived from sky surveys at a constant elevation by the Imager for Mars Pathfinder, the optical depth of the haze is estimated from HRSC data to be within 1.7 to 2.3 at the wavelength ( λ ) of 0.675 μ m. The wavelength dependence is obtained from OMEGA spectrum. It increases to 2.2–2.6 at λ = 1.35 μ m and moderately decreases to 1.2–1.8 at λ = 2.4 μ m.