36th DPS Meeting, 8-12 November 2004
Session 45 Mars Surface and Water II
Oral, Friday, November 12, 2004, 1:30-3:00pm, Lewis

[Previous] | [Session 45] | [Next]

[45.02] The effects of downwelling radiance on MER surface spectra: the evil that atmospheres do

M. Wolff (Space Science Institute), A. Ghosh (NASA/GSFC), R. Arvidson (Washington U.), P. Christensen (Arizona State University), E. Guinness (Washington U.), S. Ruff (Arizona State University), F. Seelos (Washington U.), M. Smith (NASA/GSFC), Athena Science Team

While it may not be surprising to some that downwelling radiation in the martian atmosphere may contribute a non-negligible fraction of the radiance for a given surface scene, others remain shocked and surprised (and often dismayed) to discover this fact; particularly with regard to mini-TES observations. Naturally, the relative amplitude of this sky ``contamination'' is often a complicated function of meteorological conditions, viewing geometry, surface properties, and (for the IR) surface temperature. Ideally, one would use a specialized observations to mimic the actual hemispherical-directional nature of the problem. Despite repeated attempts to obtain Pancam complete sky observations and mini-TES sky octants, such observations are not available in the MER observational database. As a result, one is left with the less-enviable, though certainly more computationally intensive, task of connecting point observations (radiance and derived meteorological parameters) to a hemispherical integral of downwelling radiance. Naturally, one must turn to a radiative transfer analysis, despite oft-repeated attempts to assert otherwise. In our presentation, we offer insight into the conditions under which one must worry about atmospheric removal, as well as semi-empirical approaches (based upon said radiative transfer efforts) for producing the correction factors from the available MER atmospheric observations.

This work is proudly supported by the MER program through NASA/JPL Contract No. 1242889 (MJW), as well as the contracts for the co-authors.

[Previous] | [Session 45] | [Next]

Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.