Spectral Albedo of Dusty Martian H2O Snow and Ice

Abstract

Recent evidence of exposed H2O ice on Mars suggests that this ice was deposited as dusty ( <1%) of martian dust can lower the albedo of H2O ice at visible wavelengths from ∼1.0 to ∼0.1. Additionally, our model indicates that dusty (>0.01% dust) firn and glacier ice have a lower albedo than pure dust, making them difficult to distinguish in visible or near-infrared images commonly used to detect H2O ice on Mars. Observations of excess ice at the Phoenix landing site are matched by 350-μm snow grains with 0.015% dust, indicating that the snow has not yet metamorphosed into glacier ice. Our model results can be used to characterize orbital observations of martian H2O ice and refine climate-model predictions of ice stability.