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4. ASAC_757_LD_d18O

Description

LD2.1ky-grid4y - Law Dome d18O data 2100BP (Present=2000AD) to 1996 as 4-year averages.

Data set used in:
Jones, P.D. and M.E. Mann, Climate Over Past Millennia, Rev. Geo. 42(2), RG2002, doi:10.1029/2003RG000143,

Mann, M.E. and Jones, P.D. Global Surface Temperatures over the Past Two Millennia, GRL 30(15), 1820, doi: 10.1029/2003GL017814

Records for this site are in active development: check with tas.van.ommen@aad.gov.au for information on updated or improved Law Dome isotope data sets.

Notes:
Ages older than 700BP estimated from flow-model constrained by layer-thickness data (similar to Morgan et al., J. Glaciol, 43(143), 3-10, 1997).
Estimated error at 2ky BP on the order of a few decades.
Ages younger than 700BP from layer counting. Estimated error +/-1 year at 700BP scaling to absolute (zero error) from 193-0BP.

d18O values in per mille. Approximate accuracy of individual measurements 0.1 per mille, but each datum presented here is an integration of between 4 and 40 individual measurements, dependent upon age and sampling scheme.

For conversion to temperature, values of ~0.2-0.3 per mille/degree C are deduced from short-term comparisons. Longer term comparison of seasonal amplitude (van Ommen and Morgan, JGR, 102(D8), 1997) indicates conversion coefficient of 0.44 per mille/degree C. Spatially derived conversion coefficients are on the order of 0.6-0.7 pe r mille/degree C, but are unlikely to be appropriate.

Note on annual phasing:
A year for the purposes of averaging of the resolved-annual cycles, is by convention marked by the isotope maximum. Thus, calendar year 1994, for example, starts with the isotope peak in the Austral summer of 1993/1994 and concludes at the 1994/1995 peak. Studies show that on the average, the isotope peak occurs around January 10 (van Ommen and Morgan, JGR, 102(D8), 9351-9357, 1997).

This work was completed as part of ASAC/AAS project 757.

Quality

This is an older dataset that is actively being updated. It is therefore recommended that users contact the investigator before using these data to check if a more up-to-date version is available.

Access

These data are publicly available for download from the provided URL.

Temporal Coverages

• Start date: 2010-04-08 - Stop date: 2010-04-08

Spatial Coverages

Science Keywords

• EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE > SURFACE TEMPERATURE > AIR TEMPERATURE
• EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC TEMPERATURE
• EARTH SCIENCE > PALEOCLIMATE > ICE CORE RECORDS > ISOTOPES
• EARTH SCIENCE > PALEOCLIMATE > PALEOCLIMATE RECONSTRUCTIONS > AIR TEMPERATURE RECONSTRUCTION
• EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC CHEMISTRY > OXYGEN COMPOUNDS

Use Constraints

This data set conforms to the CCBY Attribution License
(http://creativecommons.org/licenses/by/4.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_757_LD_d18O when using these data.