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Insights into Water Mass Origins in the Central Arctic Ocean from in-situ Dissolved Organic Matter Fluorescence.
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  • Colin A Stedmon,
  • Rainer M. W. Amon,
  • Dorothea Bauch,
  • Astrid Bracher,
  • Rafael Gonçalves-Araujo,
  • Mario Hoppmann,
  • Richard A. Krishfield,
  • Samuel Laney,
  • Benjamin Rabe,
  • Heather E Reader,
  • Mats Anders Granskog
Colin A Stedmon
Technical University of Denmark, Technical University of Denmark

Corresponding Author:[email protected]

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Rainer M. W. Amon
Texas A&M University at Galveston, Texas A&M University at Galveston
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Dorothea Bauch
GEOMAR Helmholtz Centre for Ocean Research Kiel, GEOMAR Helmholtz Centre for Ocean Research Kiel
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Astrid Bracher
Alfred Wegener Institute, Alfred Wegener Institute
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Rafael Gonçalves-Araujo
Technical University of Denmark, Technical University of Denmark
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Mario Hoppmann
AWI, Germany, AWI, Germany
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Richard A. Krishfield
Woods Hole Oceanographic Institution, Woods Hole Oceanographic Institution
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Samuel Laney
Woods Hole Oceanographic Institution, Woods Hole Oceanographic Institution
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Benjamin Rabe
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
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Heather E Reader
Memorial University of Newfoundland, Memorial University of Newfoundland
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Mats Anders Granskog
Norwegian Polar Institute, Norwegian Polar Institute
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Abstract

The Arctic Ocean receives a large supply of dissolved organic matter (DOM) from its catchment and shelf sediments, which can be traced across much of the basin’s upper waters. This signature can potentially be used as a tracer. On the shelf, the combination of river discharge and sea-ice formation, modifies water densities and mixing considerably. These waters are a source of the halocline layer that covers much of the Arctic Ocean, but also contain elevated levels of DOM. Here we demonstrate how this can be used as a supplementary tracer and contribute to evaluating ocean circulation in the Arctic. A fraction of the organic compounds that DOM consists of fluoresce and can be measured using in-situ fluorometers. When deployed on autonomous platforms these provide high temporal and spatial resolution measurements over long periods. The results of an analysis of data derived from several Ice Tethered Profilers (ITPs) offer a unique spatial coverage of the distribution of DOM in the surface 800m below Arctic sea-ice. Water mass analysis using temperature, salinity and DOM fluorescence, can clearly distinguish between the contribution of Siberian terrestrial DOM and marine DOM from the Chukchi shelf to the waters of the halocline. The findings offer a new approach to trace the distribution of Pacific waters and its export from the Arctic Ocean. Our results indicate the potential to extend the approach to separate freshwater contributions from, sea-ice melt, riverine discharge and the Pacific Ocean.
Jul 2021Published in Journal of Geophysical Research: Oceans volume 126 issue 7. 10.1029/2021JC017407