Global characterization of the Martian global dust optical depth with 2.7 μm observations by OMEGA/MEx
Résumé
Method: In this analysis, we developed a new method to retrieve the dust optical depth using the atmospheric 2.77 μm CO2 absorption band. Typically, this band saturates during nadir observations when surface pressures is greater than approximately 400 Pa in the Martian environments, resulting in almost zero observed radiance under low dust conditions. However, when the aerosols are lifted into the atmosphere, reflected sunlight by aerosols can be detected in nadirobservations. We utilized this technique to retrieve dust optical depth in the atmosphere using the L-channel of OMEGA at 2.77 μm used here. For the retrievals of the dust optical depth, we employed a Look-up-table method [8,9] that calculates many synthetic spectra at 2.77 μm in advance for tabulated grid values of physical parameters (such as dust opacity, observing geometry, atmospheric temperature, etc) by DISORT radiative transfer module [10] implemented in the ARS code [11]. With this method, an instantaneous retrieval of dust optical depth is possible by comparing them with observed spectra.
Domaines
Planète et Univers [physics]Origine | Fichiers produits par l'(les) auteur(s) |
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