Spectral reflectances of environmental surfaces for solar radiation

Field investigations on spectral hemispherical reflectances of typical natural and artificial surfaces in urban and rural areas (environmental surfaces) have been performed for solar irradiation in the wavelength range from 0.4 to 1.7 μm. Reflectance measurement is carried out accurately by a newly designed compact field spectrometer using an optical fiber and an integrating sphere with a wide view angle, regardless of the angular distribution of incident and reflected solar radiation. The reflectances of all environmental surfaces except snow cover are low in the visible region. A large difference is found between real surfaces and clean specimens. As the solar height decreases, the reflectances of vegetative fields become clearly higher in the infrared region. As the water content increases, the reflectances of permeable environmental surfaces become lower mainly in the infrared region.