Bailey, H. L., Klein, E. S., & Welker, J. M. ( 2019). Synoptic and mesoscale mechanisms drive winter precipitation δ18O/δ2H in south‐central Alaska. Journal of Geophysical Research: Atmospheres, 124, 4252– 4266. https://doi.org/10.1029/2018JD030050
Synoptic and mesoscale mechanisms drive winter precipitation δ¹⁸O/δ²H in South‐Central Alaska
|Author:||Bailey, Hannah L.1,2; Klein, Eric S.3; Welker, Jeffrey M.1,2|
1Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland and UArctic
2Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, USA
3Department of Geological Sciences, University of Alaska Anchorage, Anchorage, AK, USA
|Persistent link:|| http://urn.fi/urn:nbn:fi-fe2019062822320
American Geophysical Union,
|Publish Date:|| 2019-09-14
Measurements of oxygen and hydrogen stable isotopes in precipitation (δ¹⁸OP and δ²HP) provide a valuable tool for understanding modern hydrological processes and the empirical foundation for interpreting paleoisotope archives. However, long‐term data sets of modern δ¹⁸OP and δ²HP in southern Alaska are entirely absent, thus limiting our insight and application of regionally defined climate‐isotope relationships in this proxy‐rich region. We present and utilize a 13‐year‐long record of event‐based δ¹⁸OP and δ²HP data from Anchorage, Alaska (2005–2018, n = 332), to determine the mechanisms controlling precipitation isotopes. Local surface air temperature explains ~30% of variability in the δ¹⁸OP data with a temperature‐δ¹⁸O slope of 0.31 ‰/°C, indicating that δ¹⁸OP archives may not be suitable paleo‐thermometers in this region. Instead, back‐trajectory modeling reveals how winter δ¹⁸OP/δ²HP reflects synoptic and mesoscale processes in atmospheric circulation that drive changes in the passage of air masses with different moisture sources, transport, and rainout histories. Specifically, meridional systems—with either northerly flow from the Arctic or southerly flow from the Gulf of Alaska—have relatively low δ¹⁸OP/δ²HP due to progressive cooling and removal of precipitation as it condenses with altitude over Alaska's southern mountain ranges. To the contrary, zonally derived moisture from either the North Pacific and/or Bering Sea retains relatively high δ¹⁸OP/δ²HP values. These new data contribute a better understanding of the modern Alaska water isotope cycle and provide an empirical basis for interpreting paleoisotope archives in context of regional atmospheric circulation.
Journal of geophysical research. Atmospheres
|Pages:||4252 - 4266|
|Type of Publication:||
A1 Journal article – refereed
|Field of Science:||
1172 Environmental sciences
H. L. B. gratefully acknowledges a Fulbright‐Lloyds of London award for funding during preparation of this manuscript, as well as a University of the Arctic Chairship award to J. M. W. The authors thank Annie Brownlee and Matthew Rogers at UAA for the technical analyses of samples. NSF MRI grant (OPP 0923571) awarded to J. M. W. supported the isotope analyses.
The Anchorage stable isotope data set is available in Data Set S1. The authors declare no competing interests.
© 2019. American Geophysical Union.