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Preprints
https://doi.org/10.5194/acp-2020-340
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-2020-340
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 18 May 2020

Submitted as: research article | 18 May 2020

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This preprint is currently under review for the journal ACP.

Baffin Bay sea ice extent and synoptic moisture transport drive water vapor isotope (δ18O, δD, d-excess) variability in coastal northwest Greenland

Pete D. Akers1, Ben G. Kopec2, Kyle S. Mattingly3, Eric S. Klein4, Douglas Causey2, and Jeffrey M. Welker2,5,6 Pete D. Akers et al.
  • 1Institut des Géosciences et l'Environnement, CNRS, Saint Martin d'Hères, 38400, France
  • 2Department of Biological Sciences, University of Alaska Anchorage, Anchorage, 99508, AK, USA
  • 3Institute of Earth, Ocean, and Atmospheric Sciences, Rutgers University, Piscataway, 08854, NJ, USA
  • 4Department of Geological Sciences, University of Alaska Anchorage, Anchorage, 99508, AK, USA
  • 5Ecology and Genetics Research Unit, University of Oulu, Oulu, 90014, Finland
  • 6University of the Arctic-UArctic

Abstract. At Thule Air Base on the coast of Baffin Bay (76.51° N 68.74° W), we continuously measured water vapor isotopes (δ18O, δD) at high frequency (1 s−1) from August 2017 through August 2019. Our resulting record, including derived deuterium-excess (dxs) values, allows for analysis of isotopic–meteorological relationships at an unprecedented level of detail and duration for High Arctic Greenland. We examine isotopic variability across multiple temporal scales from daily to annual, revealing that isotopic values at Thule are determined by five interacting factors: (a) local air temperature, (b) local marine moisture availability, (c) the NAO, (d) surface wind regime, and (e) land-based evaporation/sublimation. Each factor's relative importance changes in response to seasonal shifts in Thule's environment, largely driven by the sea ice extent in northern Baffin Bay. Winter sea ice coverage forces distant sourcing of vapor that is isotopically light from fractionation during transport and prevents isotopic exchange with local waters. Late spring sea ice breakup triggers a rapid isotopic change at Thule as the newly open ocean supplies warmth and moisture that is 10 ‰ and 70 ‰ higher in δ18O and δD, respectively, and 13 ‰ lower in dxs. Sea ice retreat also leads to other environmental changes, such as sea breeze development, that dramatically alter the nature of relationships between isotopes and many meteorological variables in summer. On shorter temporal scales, enhanced southerly flow promoted by negative NAO conditions produce higher δ18O and δD values and lower dxs values. Diel isotopic cycles are generally very small as a result of a moderated coastal climate and counteracting isotopic effects of the sea breeze and local evaporation. Future losses in Baffin Bay sea ice extent will likely shift mean annual isotopic compositions toward more summer-like values, and past reductions should be similarly preserved in local glacial ice. These findings highlight the strong influence local environment has on isotope dynamics and the need for dedicated, multi-season monitoring to fully understand the controls on water vapor isotope variability.

Pete D. Akers et al.

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Pete D. Akers et al.

Data sets

Thule, Greenland, 10 minute water vapor isotopes (δ18O, δD, d-excess), August 2017 - August 2019 P. D. Akers, J. M. Welker, and B. G. Kopec https://doi.org/10.18739/A21J9779S

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Thule, Greenland, 10 minute water vapor isotopes (δ18O, δD, d-excess), August 2017 - August 2019 P. D. Akers, J. M. Welker, and B. G. Kopec https://doi.org/10.18739/A21J9779S

Pete D. Akers et al.

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Short summary
Isotopes of water vapor recorded for two years at a site in coastal northern Greenland respond reflect sea ice cover in nearby Baffin Bay. We see distinct isotopic values when Baffin Bay is ice covered in winter versus open in summer, and the spring sea ice break up is very clear. Nearby ice cores from the Greenland Ice Sheet should preserve past changes in Baffin Bay sea ice, and this will help us better understand how the Arctic environment and water cycle responds to global climate change.
Isotopes of water vapor recorded for two years at a site in coastal northern Greenland respond...
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