Record Details
Characterizing seawater oxygen isotopic variability in a regional ocean modeling framework: Implications for coral proxy records
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Characterizing seawater oxygen isotopic variability in a regional ocean modeling framework: Implications for coral proxy records |
| Names |
Stevenson, S.
(creator) Powell, B. S. (creator) Merrifield, M. A. (creator) Cobb, K. M. (creator) Nusbaumer, J. (creator) Noone, D. (creator) |
| Date Issued | 2015-11 (iso8601) |
| Note | To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by the American Geophysical Union and published by John Wiley & Sons, Inc. It can be found at: http://agupubs.onlinelibrary.wiley.com/agu/journal/10.1002/%28ISSN%291944-9186/ |
| Abstract | Reconstructions of the El Niño–Southern Oscillation (ENSO) are often created using the oxygen isotopic ratio in tropical coral skeletons (δ¹⁸O). However, coral δ¹⁸O can be difficult to interpret quantitatively, as it reflects changes in both temperature and the δ¹⁸O value of seawater. Small-scale (10–100 km) processes affecting local temperature and seawater δ¹⁸O are also poorly quantified and contribute an unknown amount to intercoral δ¹⁸O offsets. A new version of the Regional Ocean Modeling System capable of directly simulating seawater δ¹⁸O (isoROMS) is therefore presented to address these issues. The model is used to simulate δ¹⁸O variations over the 1979–2009 period throughout the Pacific at coarse (O(50 km)) resolution, in addition to 10 km downscaling experiments covering the central equatorial Pacific Line Islands, a preferred site for paleo-ENSO reconstruction from corals. A major impact of downscaling at the Line Islands is the ability to resolve fronts associated with tropical instability waves (TIWs), which generate large excursions in both temperature and seawater δ¹⁸O at Palmyra Atoll (5.9°N, 162.1°W). TIW-related sea surface temperature gradients are smaller at neighboring Christmas Island (1.9°N, 157.5°W), but the interaction of mesoscale features with the steep island topography nonetheless generates cross-island temperature differences of up to 1°C. These nonlinear processes alter the slope of the salinity:seawater δ¹⁸O relationship at Palmyra and Christmas, as well as affect the relation between coral δ¹⁸O and indices of ENSO variability. Consideration of the full physical oceanographic context of reef environments is therefore crucial for improving δ¹⁸O-based ENSO reconstructions. |
| Genre | Article |
| Identifier | Stevenson, S., Powell, B. S., Merrifield, M. A., Cobb, K. M., Nusbaumer, J., & Noone, D. (2015). Characterizing seawater oxygen isotopic variability in a regional ocean modeling framework: Implications for coral proxy records. Paleoceanography, 30(11), 1573-1593. doi:10.1002/2015PA002824 |
