Time variability of Martian bolometric albedo

A time series of calibrated bolometric albedo maps of Mars is presented which establish accurate values of surface bolometric albedo and demonstrate changes in the bolometric appearance of specific regions with time of year and atmospheric conditions. The maps were constructed from Viking infrared thermal mapping data and provide global coverage at latitudes between -60 and +60 deg at 1 x 1 deg spatial resolution for a period spanning a Martian year and including the global dust storms of 1977. During dust-free periods, the bolometric albedo maps are found to be similar to classical earth-based visual albedo maps. A distinctly bimodal distribution of bolometric surface albedos is obtained even during the dust storms, with typical Lambert albedos of 0.27 and 0.16 for the bright and dark Martian surfaces, respectively. Atmospheric effects including dust storms are found to influence strongly apparent surface albedos, especially for dark areas, while neither bright nor dark regions show measurable long-term variations of bolometric albedo during clear periods.