An approach to estimate the freshwater contribution from glacial melt and precipitation in East Greenland shelf waters using colored dissolved organic matter (CDOM)

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Stedmon, Colin, Granskog, Mats A., Dodd, Paul A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: /dk/atira/pure/sustainabledevelopmentgoals/climate_action; name=SDG 13 - Climate Action; Arctic Ocean; East Greenland; Fram Strait; Greenland; greenlandic; Ice Sheet; North Atlantic; Sea ice
• Online Access: https://orbit.dtu.dk/en/publications/6cc138d5-474f-4327-b8ca-650e7f88c320; https://doi.org/10.1002/2014JC010501

Changes in the supply and storage of freshwater in the Arctic Ocean and its subsequent export to the North Atlantic can potentially influence ocean circulation and climate. In order to understand how the Arctic freshwater budget is changing and the potential impacts, it is important to develop and refine empirical approaches for tracing freshwater contributions. This in turn can help develop and validate model simulations. Arctic rivers are an important source of freshwater and stable oxygen isotope measurements are used to separate contributions from meteoric water (river, glacial, and precipitation) and sea ice melt. We develop this approach further and investigate the use of an additional tracer, colored dissolved organic matter (CDOM), which is largely specific to freshwater originating from Arctic rivers. A robust relationship between the freshwater contribution from meteoric water and CDOM is derived from 4 years of measurements in Fram Strait (2009-2012), combined with measurements from the East Greenland shelf and Dijmpha Sound (NE Greenland). Results confirm a high contribution of riverine CDOM in Arctic halocline waters with salinities >31.5 and indicate the importance of shelf processes (riverine input and sea ice formation), while previously, these waters where thought to be derived from open sea processes (cooling and sea ice formation) in the northern Barents and Kara Seas. In Greenlandic coastal waters the meteoric water contribution is influenced by Greenland ice sheet meltwater and deviations from the CDOM-meteoric water relationships found are applied to quantify meltwater contribution along the East Greenland shelf waters (0-13%)