University of Oulu

Akers, P. D., Kopec, B. G., Mattingly, K. S., Klein, E. S., Causey, D., and Welker, J. M.: Baffin Bay sea ice extent and synoptic moisture transport drive water vapor isotope (δ¹⁸O, δ²H, and deuterium excess) variability in coastal northwest Greenland, Atmos. Chem. Phys., 20, 13929–13955, https://doi.org/10.5194/acp-20-13929-2020, 2020.

Baffin Bay sea ice extent and synoptic moisture transport drive water vapor isotope (δ¹⁸O, δ²H, and deuterium excess) variability in coastal northwest Greenland

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Author: Akers, Pete D.1; Kopec, Ben G.2; Mattingly, Kyle S.3;
Organizations: 1Institut des Géosciences et l'Environnement, CNRS, 38400 Saint Martin d'Hères, France
2Department of Biological Sciences, University of Alaska Anchorage, 99508 Anchorage, AK, USA
3Institute of Earth, Ocean, and Atmospheric Sciences, Rutgers University, 08854 Piscataway, NJ, USA
4Department of Geological Sciences, University of Alaska Anchorage, 99508 Anchorage, AK, USA
5Ecology and Genetics Research Unit, University of Oulu, 90014 Oulu, Finland
6University of the Arctic (UArctic), c/o University of Lapland, 96101 Rovaniemi, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 13.5 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe202102124665
Language: English
Published: Copernicus Publications, 2020
Publish Date: 2021-02-12
Description:

Abstract

At Thule Air Base on the coast of Baffin Bay (76.51° N, 68.74° W), we continuously measured water vapor isotopes (δ¹⁸O, δ²H) at a high frequency (1 s⁻¹) from August 2017 through August 2019. Our resulting record, including derived deuterium excess (dxs) values, allows an 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 interannual, revealing that isotopic values at Thule are predominantly controlled by the sea ice extent in northern Baffin Bay and the synoptic flow pattern. This relationship can be identified through its expression in the following five interacting factors: (a) local air temperature, (b) local marine moisture availability, (c) the North Atlantic Oscillation (NAO), (d) surface wind regime, and (e) land-based evaporation and sublimation. Each factor's relative importance changes based on the temporal scale and in response to seasonal shifts in Thule's environment. Winter sea ice coverage forces distant sourcing of vapor that is isotopically light from fractionation during transport, while preventing isotopic exchange with local waters. Sea ice breakup in late spring triggers a rapid isotopic change at Thule as the newly open ocean supplies warmth and moisture that has ∼10 ‰ and ∼70 ‰ higher δ¹⁸O and δ²H values, respectively, and ∼10 ‰ lower dxs values. Sea ice retreat also leads to other environmental changes, such as sea breeze development, that radically alter the nature of relationships between isotopes and many meteorological variables in summer. On synoptic timescales, enhanced southerly flow promoted by negative NAO conditions produces higher δ¹⁸O and δ²H values and lower dxs values. Diel isotopic cycles are generally very small as a result of a moderated coastal climate and the counteracting isotopic effects of the sea breeze, local evaporation, and convection. Future losses in Baffin Bay's sea ice extent will likely shift mean annual isotopic compositions toward more summer-like values, and local glacial ice could potentially preserve isotopic evidence of past reductions. These findings highlight the influence that the local environment can have on isotope dynamics and the need for dedicated, multiseason monitoring to fully understand the controls on water vapor isotope variability.

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Series: Atmospheric chemistry and physics
ISSN: 1680-7316
ISSN-E: 1680-7324
ISSN-L: 1680-7316
Volume: 20
Issue: 22
Pages: 13929 - 13955
DOI: 10.5194/acp-20-13929-2020
OADOI: https://oadoi.org/10.5194/acp-20-13929-2020
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Subjects:
Funding: This research has been supported by the National Science Foundation Office of Polar Programs (grant nos. 1504141 and 1852614). This project has also been supported by funding for the inaugural UArctic Research Chair position held by Jeffrey M. Welker.
Copyright information: © Author(s) 2020. This work is distributed underthe Creative Commons Attribution 4.0 License.
  https://creativecommons.org/licenses/by/4.0/