Identification

Title

Characterizing seawater oxygen isotopic variability in a regional ocean modeling framework: Implications for coral proxy records

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.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d79z96dv

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2015-11-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact