Estimation of Anisotropic Radiance from a Glacier Surface - Ground Based Spectrometer Measurements and Satellite-derived Reflectances

摘要

A glacier surface comprises mainly snow, firn and ice together with various transition features. Depending on the level of dirt content and due to different physical characteristics of surface materials, neighbouring surface patches on a glacier show distinct wavelength-dependent reflection patterns. Under ideal conditions, the albedo can be calculated when both all incoming and outgoing radiative fluxes from a surface are measured. Here, simple ground-based nadir measurements of reflected surface radiation were carried out on the Hintereis glacier (Austria) using a portable spectrometer. In situ measurements were compared to reflection values found in a Landsat ETM+ image acquired in the preceding week. Radiometric, atmospheric and topographic corrections were performed on the image. Parameterised equations were constructed to estimate reflectance from the glacier surface using both in situ and image values.