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G. Rinaldi (IFSI-INAF, Rome and CISAS, Univ. of Padua, Italy), V. Formisano (IFSI-INAF, Rome, Italy), N. I. Ignatiev, L. V. Zasova (IKI-RSSI, Moscow, Russia and IFSI-INAF, Rome, Italy)
The solar radiation mesured by PFS inside the 2.7 \mum CO2 band can give information about the aerosols present in the Martian atmosphere. Up today in the leterature the work of Titov et al. Indicate a direct relation between radiance level and aerosols dust opacity. Interpreted accordingly, PFS data would indicate that an extremely high dust opacity is observed in the northem summer season. We show here, computing a number of synthetic spectra (numerical experiments performed for different conditions), that high altitudes water ice clouds can significantly contribute to the observed radiation level. Also the vertical profile of dust (exponential) versus high altitude dust leyers can change drammatically the observed radiance level. The results from our calculation, and their comparison with PFS data, indicate that in the northem summer we have to consider type II dust / water ice particles of size up to 3-4\ mum. A model of dust grains covered by water ice has been used to describe a high altitude dust/ice cloud. The results indicate good fitting of some aspects of the observation, but the radiance slope inside the 2.7 \mum CO2 band indicate the need to change dust composition.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.