Abstract
AbstractThe surface spectral albedo was measured over coastal landfast sea ice in Prydz Bay (off Zhongshan Station), East Antarctica from 5 October to 26 November of 2016. The mean albedo decreased from late-spring to early-summer, mainly responding to the change in surface conditions from dry (phase I) to wet (phase II). The evolution of the albedo was strongly influenced by the surface conditions, with alternation of frequent snowfall events and katabatic wind that induce snow blowing at the surface. The two phases and day-to-day albedo variability were more pronounced in the near-infrared albedo wavelengths than in the visible ones, as the near-infrared photons are more sensitive to snow metamorphism, and to changes in the uppermost millimeters and water content of the surface. The albedo diurnal cycle during clear sky conditions was asymmetric with respect to noon, decreasing from morning to evening over full and patchy snow cover, and decreasing more rapidly in the morning over bare ice. We conclude that snow and ice metamorphism and surface melting dominated over the solar elevation angle dependency in shaping the albedo evolution. However, we realize that more detailed surface observations are needed to clarify and quantify the role of the various surface processes.
Highlights
Sea ice is a strong thermal insulator and mechanical lid between the atmosphere and ocean, and reduces the air-sea exchange of heat, water vapor, and momentum
The observed albedo was higher for the cold, dry surface and gradually decreased during the melting season, obviously most markedly in the near-infrared band because of its higher sensitivity to changes in the snow optical equivalent grain size caused by the snow metamorphism and melt
Over the coastal landfast sea ice in Prydz Bay continuous, automatic spectral albedo measurements were carried out for almost 2 months in the austral spring 2016, and the results are analyzed in this paper
Summary
Sea ice is a strong thermal insulator and mechanical lid between the atmosphere and ocean, and reduces the air-sea exchange of heat, water vapor, and momentum. The ice albedo can increase from 0.54 to 0.89 after the occurrence of snowfall (Pirazzini, 2004), and snow thickness is an important factor influencing Antarctic landfast sea-ice albedo (Yang and others, 2016). Comparing with the Arctic observations (e.g. Perovich and others, 2002; Laine, 2004; Pirazzini and others, 2006; Perovich and others, 2007; Nicolaus and others, 2010a; Lei and others, 2012; Perovich and others, 2012; Riihelä and others, 2013), sea-ice albedo observations in Antarctica are even more sparse (Allison and others, 1993; Pirazzini, 2004; Brandt and others, 2005; Weiss and others, 2012; Yang and others, 2016), in particular continuous time series that cover the seasonal evolution and interannual variability (Yu and others, 2017).
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