In situ measurement of the solar radiance distribution within sea ice in Liaodong Bay, China

Abstract

Understanding the optical properties of polluted sea ice is important for analyzing remote sensing data, and studying energy balance. Liaodong Bay in China provides a kind of representative of dirty sea ice for there are many industrial and residential areas surrounding it. Optical properties of sea ice were observed. Albedos for different types of sea ice surface were obtained, and their peaks would tend to shift to longer wavelengths for the high concentrations of PM and CDOM in sea ice. Upwelling (K-u) and downwelling (K-d) irradiance extinction coefficients profiles were obtained in situ with a self-made instrument. At 586 nm, the maximum K-u reached 13.68 m(-1) in a layer close to ice bottom, while the maximum K-d reached 15.52 m(-1) in surface layer. Because understanding the energy distribution in sea ice is important to research mass budget in air-ice-sea, solar radiance distribution in sea ice was observed in a series of bored holes in situ. From 4 cm to ice bottom, the logarithms of radiance profiles almost decrease linearly with increasing the path length of light transfer. Because sea ice is a highly scattering medium and the effects of scattering become stronger with increasing depth, the dependence of scattering light on scattering angle (theta) becomes weaker with increasing depth. An optical model was brought forward to describe the solar radiance distribution at a random depth and theta. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.