Spectral curves of surface reflectance in some Antarctic regions

Four surface reflectance models of solar radiation were determined by exami ning several sets of field measurements taken for clear-sky conditions at v arious sites in Antarctica Each model consists of the mean spectral curve o f surface reflectance in the 0.252.7 mum wavelength range and of the depend ence curve of total albedo on the solar elevation angle hi within the range from 5 degrees to 55 degrees. The TNB (Terra Nova Bay) model refers to a r ocky terrain where granites are predominant; the NIS (Yansen Ice Sheet) mod el to a glacier surface made uneven by sastrugi and streaked by irregular f ractures; the HAP (High Altitude Plateau) model to a flat ice surface cover ed by fresh snow and scored by light sastrugi; and the RIS (Ross Ice Shelf) model to an area covered bq the sea ice pack presenting many discontinuiti es in the reflectance features, due to melt water lakes, puddles, refrozen ice and snow pots. The reflectance curve obtained for the TNB model present s gradually increasing values as wavelength increases through the visible s pectral range and almost constant values at infrared wavelengths, giving a total albedo value equal to 0.264 at h = 30 degrees, which increases by abo ut 80% through the lower range of h and decreases by 12% through the upper range. The reflectance curves of the NIS, HAP and RIS models are all peaked at visible wavelengths and exhibit decreasing values throughout the infrar ed spectral range, giving values of total albedo equal to 0.464, 0.738 and 0.426 at h = 30 degrees, respectively. These values were estimated to incre ase by 8-14% as h decreases from 30 degrees to 5 degrees and to decrease bS 2-4% only as h increases from 30 degrees to 55 degrees.