Changes in Arctic sea ice result in increasing light transmittance and absorption

• Published in: Geophysical research letters 2012-12, Vol.39 (24), p.n/a
• Main Authors: Nicolaus, M., Katlein, C., Maslanik, J., Hendricks, S.
• Format: Article
• Language: English
• Subjects: Absorption; Albedo; Climate change; Cryosphere; Earth; Earth sciences; Earth, ocean, space; energy balance; Exact sciences and technology; Ice; Marine ecosystems; Mass balance models; Oceans; optical properties; Sea ice; Snow; Summer; Transmittance; Upper ocean
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2012GL053738

Arctic sea ice has declined and become thinner and younger (more seasonal) during the last decade. One consequence of this is that the surface energy budget of the Arctic Ocean is changing. While the role of surface albedo has been studied intensively, it is still widely unknown how much light penetrates through sea ice into the upper ocean, affecting sea‐ice mass balance, ecosystems, and geochemical processes. Here we present the first large‐scale under‐ice light measurements, operating spectral radiometers on a remotely operated vehicle (ROV) under Arctic sea ice in summer. This data set is used to produce an Arctic‐wide map of light distribution under summer sea ice. Our results show that transmittance through first‐year ice (FYI, 0.11) was almost three times larger than through multi‐year ice (MYI, 0.04), and that this is mostly caused by the larger melt‐pond coverage of FYI (42 vs. 23%). Also energy absorption was 50% larger in FYI than in MYI. Thus, a continuation of the observed sea‐ice changes will increase the amount of light penetrating into the Arctic Ocean, enhancing sea‐ice melt and affecting sea‐ice and upper‐ocean ecosystems. Key Points Light penetration into the ocean will increase in a changing Arctic Transmittance through first‐year ice is 3x larger than through multi‐year ice Energy absorption is 50% larger in first‐year ice than in multi‐year ice