Local topographic effects on photometry and reflectance spectra of planetary surfaces: An example based on lunar photometry

Abstract

The photometric properties of the average lunar surface are characterized using Hapkes equations and whole disk observations ranging from 0.36 to 1.06 micrometers. Synthetic spectra across a crater topographic profile arecreated using the modeling results. The synthetic spectra are examined for spectral variations created by changes in lighting conditions induced by the topography. Changes above the modeling uncertainties are seen in both spectral slope and band depths, though the most pronounced change is in band depth. The data have insufficient spectral resolution to determine if there are any changes in band center due to photometric effects. No additional absorption features are introduced by the photometry. These results have serious implications on the interpretation of spectral observations in terms of abundance estimates and alteration processes as a function of location and association with geologic features.