Mapping the Martian polar ice caps: Applications of terrestrial optical remote sensing methods

Abstract

With improvements in both instrumentation and algorithms, methods for mapping terrestrial snow cover using optical remote sensing data have progressed significantly over the past decade. Multispectral data can now be used to determine not only the presence or absence of snow but the fraction of snow cover in a pixel. Radiative transfer models have been used to quantify the nonlinear relationship between surface reflectance and grain size thereby providing the basis for mapping snow grain size from surface reflectance images. Model-derived characterization of the bidirectional reflectance distribution function provides the means for converting measured bidirectional reflectance to directional-hemispherical albedo. In recent work, this approach has allowed climatologists to examine the large scale seasonal variability of albedo on the Greenland ice sheet. This seasonal albedo variability results from increases in snow grain size and exposure of the underlying ice cap as the seasonal snow cover ablates away. With the current Mars Global Surveyor and future missions to Mars, it will soon be possible to apply some of these terrestrial mapping methods to learn more about Martian ice properties, extent, and variability. Distinct differences exist between Mars and Earth ice mapping conditions, including surface temperature, ice type, ice-mineral mixtures, and atmospheric properties, so a direct application of terrestrial snow and ice mapping methods may not be possible. However, expertise in mapping and interpreting terrestrial snow and ice will contribute to the inventory of techniques for mapping planetary ices. Furthermore, adaptation of terrestrial methods will provide a basis for comparison of terrestrial and planetary cryosphefic components. Copyright 1998 by the American Geophysical Union.