Optical studies of Antarctic sea ice

Abstract

During the austral winter 1986 the spectral albedo of both snow-covered and bare sea ice was measured over the wavelength range 400–1350 nm in the eastern Weddell Sea. The albedo shows high values and a week wave-length dependence in the visible part of the spectrum and a strong decrease with increasing wavelength in the near IR. Maxima in albedo correspond with minima in ice absorption. For relatively thin ice the albedo depends strongly on ice thickness. Additionally the bidirectional reflectance of sea ice was studied in the laboratory. For ice thicknesses of a few millimeters nearly specular reflectance is found. With growing ice thickness more scattering within the ice occurs and consequently the intensity of the sidewards scattered radiation increases. The reflectance distribution shows a peak in the forward direction which is less developed with thicker ice and smaller crystal size.