Aphelion water-ice cloud mapping and property retrieval using the OMEGA imaging spectrometer onboard Mars Express

Abstract : Mapping of the aphelion clouds over Tharsis and retrieval of their particle size and visible opacity are made possible by the OMEGA imaging spectrometer aboard Mars Express. Observations cover the period from MY26 Ls=330{degree sign} to MY29 Ls=180{degree sign} and are acquired at various local times, ranging from 8AM to 6PM. Cloud maps of the Tharsis region constructed using the 3.1µm ice absorption band reveal the seasonal and diurnal evolution of aphelion clouds. Four distinct types of clouds are identified: morning hazes, topographically controlled hazes, cumulus clouds and thick hazes. The location and time of occurrence of these clouds are analyzed and their respective formation process is discussed. An inverse method for retrieving cloud particle size and opacity is then developed and can only be applied to thick hazes. The relative error of these measurements is less than 30% for cloud particle size and 20% for opacity. Two groups of particles can be distinguished. The first group is found over flat plains and is composed of relatively small particles, ranging in size from 2 to 3.5µm. The second group is characterized by particle sizes of ~5µm which appear to be quite constant over Ls and local time. It is found west of Ascraeus and Pavonis Mons, and near Lunae Planum. These regions are preferentially exposed to anabatic winds, which may control the formation of these particles and explain their distinct properties. The water ice column is equal to 2.9pr.µm on average, and can reach 5.2pr.µm in the thickest clouds of Tharsis.
Liste complète des métadonnées

Littérature citée [76 références]  Voir  Masquer  Télécharger

Contributeur : Catherine Cardon <>
Soumis le : lundi 11 avril 2016 - 10:34:16
Dernière modification le : jeudi 7 février 2019 - 16:57:23
Document(s) archivé(s) le : mardi 12 juillet 2016 - 11:54:50


Fichiers éditeurs autorisés sur une archive ouverte



Jean-Baptiste Madeleine, Francois Forget, Aymeric Spiga, Michael J. Wolff, Franck Montmessin, et al.. Aphelion water-ice cloud mapping and property retrieval using the OMEGA imaging spectrometer onboard Mars Express. Journal of Geophysical Research. Planets, Wiley-Blackwell, 2012, 117 (E11), pp.E00J07. 〈10.1029/2011JE003940〉. 〈hal-00678749〉



Consultations de la notice


Téléchargements de fichiers