17 January 2002 Comparison of different methods for the determination of the average UV albedo in a mountainous terrain
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Abstract
One aim of the project CUVRA was to improve the modeling of effects of inhomogeneous albedo fields on ground UV irradiance. For the determination of the effect of heterogeneous illumination (shading effects, inclination and orientation of the facet) on the reflectivity of a facet in a mountainous region more complex approaches (than for the calculation of the reflectivity of flat surfaces) have to be chosen. We determined the 'effective' albedo for the surroundings of the Observatory Sonnblick (3106 m) by using three different methods. The first method consisted of a combination of a 3D albedo model calculation and 1D radiative transfer calculation. By using this method and a digital elevation map, the reflectivity of the region surrounding Sonnblick Observatory was calculated. The second method was an inversion method using a 1D radiative transfer model. The routine spectral UV measurements performed at Sonnblick were used to calculate the average effective albedo. The third method was entirely experimental. An albedo measuring system was used to perform reflectivity measurements of the surrounding of Sonnblick. Overall, the results showed that the average albedo of a topographically structured surface is lower than the average albedo of a corresponding (surface with same ground characteristics) flat surface.
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Philipp Weihs, Philipp Weihs, Stana Simic, Stana Simic, G. Rengarajan, G. Rengarajan, Wolfgang Laube, Wolfgang Laube, W. Mikielewicz, W. Mikielewicz, } "Comparison of different methods for the determination of the average UV albedo in a mountainous terrain", Proc. SPIE 4482, Ultraviolet Ground- and Space-based Measurements, Models, and Effects, (17 January 2002); doi: 10.1117/12.452947; https://doi.org/10.1117/12.452947
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