Maiana Atoll Isotope (delta 18O, delta 13C) Data for 1840 to 1995
Entry ID:
G2051
|
Summary
Maiana bimonthly oxygen isotopic composition, 1840-1995. Notes on the data:
File includes columns for Year AD (bimonthly resolution = dec/jan,
feb/mar) and coral d18O (a). The coral used in this study grew (and still
does grow) at Maiana Atoll, Republic of Kiribati (1N, 173E). The colony
lies at a depth of ~6m (low tide) and is about 4m ... in height. Annual growth rate
is roughly 11mm/yr. Methods: Sampling and isotopic analysis: Cores (8.5 cm
diameter) drilled from living coral colonies were slabbed and X-rayed to
identify annual density bands and optimal sampling transects. Samples were
drilled along the growth axis continuously at 1mm resolution. Stable isotopic
analysis (d18O and d13C) of powdered samples was performed on a Micromass
Optima with Isocarb automated preparation system at the University of
Colorado's Institute for Arctic and Alpine Research. Analytical precision is
=+/-0.08 d18O and =+/-0.05 d13C. The Maiana record is continuous except for a
gap from 1901-1905, which we bridged through straight forward comparison and
splicing of data from a coral record from nearby Tarawa Atoll. Age model:
Seasonally varying d13C values and ephemeral annual density bands provide the
basis for annual age assignment. Ages were adjusted subseasonally by
comparison to major El Nino and La Nina anomalies in a regional rainfall
index (available at
http://tao.atmos.washington.edu/datasets/eqpacislandrainindex/); this procedure
allows us to align major peaks and troughs that occur within the same
calendar year with adjustments that are generally less than 3 months. Because
corals grow at variable rates throughout the year, these small chronological
adjustments are reasonable and customary (and do not affect estimates of
multi-year variability). Near the base of the core, an age adjustment of 1 year
was needed, suggesting an age uncertainty on the full record of 1 year. The
Maiana coral grew at a rate of 7-12 mm per year; we interpolated records to a
common time step of bimonthly resolution for further analysis. Replication: The
record from core MAI95-2-3 is well replicated by additional records of 65-70
years from Maiana and Aranuka, ~75 km southeast of Maiana, (JEC, FEU, and JTO,
manuscript in preparation) and by a published 97-year record from Tarawa
Atoll, ~30 km north of Maiana. Correlation coefficients among coral and
instrumental data over the common period 1950-89 are consistently high
(Maiana_correlations.txt), adding confidence to single-core reconstruction of
regional variability in western Kiribati. We focus on the MAI95-2-3 record for
further analysis because it extends the record of ENSO into pre-instrumental
periods and avoids nonstationarity that may be introduced through inclusion of
records that differ in length. The 4-coral average correlates slightly better
with instrumental data than most individual coral records, but only Mai 2-3
extends the instrumental record of ENSO. Linear correlation coefficients
demonstrate a strong agreement between the Maiana record and ENSO variability
(Table 1), and decadal averages of the Maiana record correlate significantly
over the past century (>95% confidence) with those from the Tarawa coral record
and regional rainfall indices, substantiating the reality of these more
subtle low-frequency signals (JEC, FEU, and JTO, manuscript in preparation).
On-line data are available free of charge, other forms are available for the
cost of reproduction
Geographic Coverage
Spatial coordinates
| N: 1.0 |
|
S: 1.0 |
|
E: 173.0 |
|
W: 173.0 |
Data Set Citation
Dataset Creator:
Frank Urban Julia Cole Jonathan Overpeck
Dataset Title:
Maiana Atoll Isotope (delta 18O, delta 13C) Data for 1840 to 1995
Dataset Series Name:
World Data Center for Paleoclimatology Data Contribution Series
Dataset Release Date:
2000/10
Dataset Release Place:
Boulder
Dataset Publisher:
World Data Center for Paleoclimatology, Boulder
Issue Identification:
2000-063
Online Resource:
http://www.ncdc.noaa.gov/paleo/coral/maiana.html
|
Temporal Coverage
Start Date:
1840-01-01
Stop Date:
1995-12-31
|
Location Keywords
Science Keywords
ISO Topic Category
Project
Quality
Disclaimer- While every effort has been made to ensure that these data are
accurate and reliable within the limits of the current state of the art, NOAA
cannot assume liability for any damages caused by any errors or omissions in
the data, nor as a result of the failure of the data to function on a
particular system. NOAA makes no warranty, expressed or implied, nor does the
fact of distribution constitute such a warranty.
Access Constraints
None
Use Constraints
Please cite original reference when using this data.
Ancillary Keywords
Data Set Progress
Originating Center
Data Center
Distribution
Fees:
On-line data are available free of charge
|
Personnel
WDC/PALEOCLIMATOLOGY, BOULDER
Role:
TECHNICAL CONTACT
Phone:
+1 (303) 497-6160
Fax:
+1 (303) 497-6513
Email:
paleo at noaa.gov
Contact Address:
World Data Center for Paleoclimatology
NOAA/NCDC Code E/GCx3
325 Broadway
City:
Boulder
Province or State:
CO
Postal Code:
80303
Country:
USA
|
Related URL
Link:
GET DATA
Description:
Access to Maiana data
|
Creation and Review Dates
DIF Creation Date:
2004-09-08
Last DIF Revision Date:
2009-01-21
|
|
Links
