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[49.03] Seasonal Variations of Martian Clouds and Volatiles

D. R. Klassen, W. Peppard, T. Scabarozi, Jr. (Rowan University), J. F. Bell III (Cornell University)

Using the 256x256 InSb array NSFCAM at the NASA infrared Telescope Facility we have gathered near-infrared (NIR) multi-spectral image sets of Mars over the last three oppositions. We have been working on a long term-monitoring of the Martian volatiles and now have data enough to begin making seasonal comparisons. The opposition of 1995 happened during Martian northern spring (L_S = 45\arcdeg\ - 71\arcdeg) and the opposition of 1999 happened during Martian northern summer (L_S = 90\arcdeg\ - 129\arcdeg). We present here our analyses and comparisons of the cloud coverage and compositions at these two times.

In our previous studies we developed band-ratio techniques which allow us to map the spectral signatures of both H₂O and CO₂ frosts and to distinguish between them and found evidence for clouds of CO₂ ices at the southern (winter) pole. For this paper we apply those same techniques to our newest data.

We find that at L_S = 54\arcdeg\ the northern pole is still covered by a polar hood cloud with some significant amount of CO₂ ices still present in the polar cap. By L_S = 106\arcdeg\ there is only a small H₂O ice signature with no evidence of polar clouds. The thick tropical clouds of the Martian spring have also greatly diminished in the summer, although there is still a strong cloud signature at the limbs indicating that there is significant overnight cloud formation.

Of interest is the lack of any strong CO₂ ice signatures during the northern spring/southern fall except for the ground ices still at the northern polar cap. By L_S = 129\arcdeg\ in the most extreme visible southern latitudes we see evidence of CO₂ ice clouds indicating the much colder winter climate of the southern hemisphere.

These results, once calibrated to absolute flux units, will be used to calcualte H₂O and CO₂ ice amounts in an effort to help understand the volatile cycles and total water budget of Mars.

If you would like more information about this abstract, please follow the link to http://elvis.rowan.edu/~klassen. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: klassen@rowan.edu

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