scholarly journals SHCal20 Southern Hemisphere Calibration, 0–55,000 Years cal BP

Radiocarbon ◽  
2020 ◽  
Vol 62 (4) ◽  
pp. 759-778 ◽  
Author(s):  
Alan G Hogg ◽  
Timothy J Heaton ◽  
Quan Hua ◽  
Jonathan G Palmer ◽  
Chris SM Turney ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
Calibration Curve ◽  
Data Sets ◽  
Errors In Variables ◽  
Time Intervals ◽  
Tree Ring Data ◽  
The Mean ◽  
Statistical Approaches

ABSTRACTEarly researchers of radiocarbon levels in Southern Hemisphere tree rings identified a variable North-South hemispheric offset, necessitating construction of a separate radiocarbon calibration curve for the South. We present here SHCal20, a revised calibration curve from 0–55,000 cal BP, based upon SHCal13 and fortified by the addition of 14 new tree-ring data sets in the 2140–0, 3520–3453, 3608–3590 and 13,140–11,375 cal BP time intervals. We detail the statistical approaches used for curve construction and present recommendations for the use of the Northern Hemisphere curve (IntCal20), the Southern Hemisphere curve (SHCal20) and suggest where application of an equal mixture of the curves might be more appropriate. Using our Bayesian spline with errors-in-variables methodology, and based upon a comparison of Southern Hemisphere tree-ring data compared with contemporaneous Northern Hemisphere data, we estimate the mean Southern Hemisphere offset to be 36 ± 27 14C yrs older.

scholarly journals The Influence of Calibration Curve Construction and Composition on the Accuracy and Precision of Radiocarbon Wiggle-Matching of Tree Rings, Illustrated by Southern Hemisphere Atmospheric Data Sets from AD 1500–1950

Radiocarbon ◽  
2019 ◽  
Vol 61 (5) ◽  
pp. 1265-1291 ◽  
Author(s):  
Alan G Hogg ◽  
Timothy J Heaton ◽  
Christopher Bronk Ramsey ◽  
Gretel Boswijk ◽  
Jonathan G Palmer ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Tree Ring ◽  
Calibration Curve ◽  
New Method ◽  
Ice Age ◽  
Data Sets ◽  
Accuracy And Precision ◽  
Tree Ring Data ◽  
Two Factors ◽  
Short Tree

ABSTRACTThis research investigates two factors influencing the ability of tree-ring data to provide accurate 14C calibration information: the fitness and rigor of the statistical model used to combine the data into a curve; and the accuracy, precision and reproducibility of the component 14C data sets. It presents a new Bayesian spline method for calibration curve construction and tests it on extant and new Southern Hemisphere (SH) data sets (also examining their dendrochronology and pretreatment) for the post-Little Ice Age (LIA) interval AD 1500–1950. The new method of construction allows calculation of component data offsets, permitting identification of laboratory and geographic biases. Application of the new method to the 10 suitable SH 14C data sets suggests that individual offset ranges for component data sets appear to be in the region of ± 10 yr. Data sets with individual offsets larger than this need to be carefully assessed before selection for calibration purposes. We identify a potential geographical offset associated with the Southern Ocean (high latitude) Campbell Island data. We test the new methodology for wiggle-matching short tree-ring sequences and use an OxCal simulation to assess the likely precision obtainable by wiggle-matching in the post-LIA interval.

scholarly journals Atmospheric Radiocarbon for the Period 1950–2010

Radiocarbon ◽  
2013 ◽  
Vol 55 (4) ◽  
pp. 2059-2072 ◽  
Author(s):  
Quan Hua ◽  
Mike Barbetti ◽  
Andrzej Z Rakowski
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
Organic Materials ◽  
Annual Data ◽  
Data Sets ◽  
Model Calculations ◽  
Monthly Data ◽  
Radiocarbon Data ◽  
Global Carbon

We present a compilation of tropospheric 14CO2 for the period 1950–2010, based on published radiocarbon data from selected records of atmospheric CO2 sampling and tree-ring series. This compilation is a new version of the compilation by Hua and Barbetti (2004) and consists of yearly summer data sets for zonal, hemispheric, and global levels of atmospheric 14C. In addition, compiled (and extended) monthly data sets for 5 atmospheric zones (3 in the Northern Hemisphere and 2 in the Southern Hemisphere) are reported. The annual data sets are for use in regional and global carbon model calculations, while the extended monthly data sets serve as calibration curves for 14C dating of recent, short-lived terrestrial organic materials.

scholarly journals Bayesian Evaluation of the Southern Hemisphere Radiocarbon Offset during the Holocene

Radiocarbon ◽  
2009 ◽  
Vol 51 (4) ◽  
pp. 1165-1176 ◽  
Author(s):  
Alan Hogg ◽  
Christopher Bronk Ramsey ◽  
Chris Turney ◽  
Jonathan Palmer
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Calibration Curve ◽  
Early Holocene ◽  
Data Sets ◽  
Bayesian Calibration ◽  
The Holocene ◽  
Calibration Program

While an interhemispheric offset in atmospheric radiocarbon levels from AD 1950–950 is now well established, its existence earlier in the Holocene is less clear, with some studies reporting globally uniform 14C levels while others finding Southern Hemisphere samples older by a few decades. In this paper, we present a method for wiggle-matching Southern Hemisphere data sets against Northern Hemisphere curves, using the Bayesian calibration program OxCal 4.1 with the Reservoir Offset function accommodating a potential interhemispheric offset. The accuracy and robustness of this approach is confirmed by wiggle-matching known-calendar age sequences of the Southern Hemisphere calibration curve SHCal04 against the Northern Hemisphere curve IntCal04. We also show that 5 of 9 Holocene Southern Hemisphere data sets are capable of yielding reliable offset information. Those data sets that are accurate and precise show that interhemispheric offset levels in the Early Holocene are similar to modern levels, confirming SHCal04 as the curve of choice for calibrating Southern Hemisphere samples.

scholarly journals 14C Calibration in the Southern Hemisphere and the Date of the Last Taupo Eruption: Evidence from Tree-Ring Sequences

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 155-163 ◽  
Author(s):  
R. J. Sparks ◽  
W. H. Melhuish ◽  
J.W. A. McKee ◽  
John Ogden ◽  
J. G. Palmer ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
Tree Rings ◽  
Calibration Curve ◽  
Systematic Difference ◽  
Calibration Data ◽  
Northern And Southern Hemispheres

Tree rings from a section of Prumnopitys taxifolia (matai) covering the period ad 1335–1745 have been radiocarbon dated and used to generate a 14C calibration curve for southern hemisphere wood. Comparison of this curve with calibration data for northern hemisphere wood does not show a systematic difference between 14C ages measured in the northern and southern hemispheres. A floating chronology covering 270 yr and terminating at the last Taupo (New Zealand) eruption, derived from a sequence of 10-yr samples of tree rings from Phyllocladus trichomanoides (celery pine, or tanekaha), is also consistent with the absence of a systematic north-south difference, and together with the matai data, fixes the date of the Taupo eruption at ad 232 ± 15.

scholarly journals Investigating the Interhemispheric 14C Offset in the 1st Millennium AD and Assessment of Laboratory Bias and Calibration Errors

Radiocarbon ◽  
2009 ◽  
Vol 51 (4) ◽  
pp. 1177-1186 ◽  
Author(s):  
Alan Hogg ◽  
Jonathan Palmer ◽  
Gretel Boswijk ◽  
Paula Reimer ◽  
David Brown
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
High Precision ◽  
Calibration Data ◽  
Time Intervals ◽  
Data Set ◽  
Ocean Atmosphere ◽  
Calibration Data Set

Past measurements of the radiocarbon interhemispheric offset have been restricted to relatively young samples because of a lack of older dendrochronologically secure Southern Hemisphere tree-ring chronologies. The Southern Hemisphere calibration data set SHCal04 earlier than AD 950 utilizes a variable interhemispheric offset derived from measured 2nd millennium AD Southern Hemisphere/Northern Hemisphere sample pairs with the assumption of stable Holocene ocean/atmosphere interactions. This study extends the range of measured interhemispheric offset values with 20 decadal New Zealand kauri and Irish oak sample pairs from 3 selected time intervals in the 1st millennium AD and is part of a larger program to obtain high-precision Southern Hemisphere 14C data continuously back to 200 BC. We found an average interhemispheric offset of 35 ± 6 yr, which although consistent with previously published 2nd millennium AD measurements, is lower than the offset of 55–58 yr utilized in SHCal04. We concur with McCormac et al. (2008) that the IntCal04 measurement for AD 775 may indeed be slightly too old but also suggest the McCormac results appear excessively young for the interval AD 755–785. In addition, we raise the issue of laboratory bias and calibration errors, and encourage all laboratories to check their consistency with appropriate calibration curves and invest more effort into improving the accuracy of those curves.

scholarly journals Intcal04 Terrestrial Radiocarbon Age Calibration, 0–26 Cal Kyr BP

Radiocarbon ◽  
2004 ◽  
Vol 46 (3) ◽  
pp. 1029-1058 ◽  
Keyword(s):  
Tree Ring ◽  
Calibration Curve ◽  
Statistical Approach ◽  
Data Sets ◽  
Calibration Data ◽  
Surface Mixed Layer ◽  
Data Set ◽  
Radiocarbon Age ◽  
Tree Ring Data ◽  
A Site

A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0–24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from 0–26 cal kyr BP, but with much higher resolution beyond 11.4 cal kyr BP than IntCal98. Dendrochronologically-dated tree-ring samples cover the period from 0–12.4 cal kyr BP. Beyond the end of the tree rings, data from marine records (corals and foraminifera) are converted to the atmospheric equivalent with a site-specific marine reservoir correction to provide terrestrial calibration from 12.4–26.0 cal kyr B P. A substantial enhancement relative to IntCal98 is the introduction of a coherent statistical approach based on a random walk model, which takes into account the uncertainty in both the calendar age and the 14C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The tree-ring data sets, sources of uncertainty, and regional offsets are discussed here. The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed in brief, but details are presented in Hughen et al. (this issue a). We do not make a recommendation for calibration beyond 26 cal kyr BP at this time; however, potential calibration data sets are compared in another paper (van der Plicht et al., this issue).

scholarly journals Marine04 Marine Radiocarbon Age Calibration, 0–26 Cal Kyr Bp

Radiocarbon ◽  
2004 ◽  
Vol 46 (3) ◽  
pp. 1059-1086 ◽  
Author(s):  
Konrad A Hughen ◽  
Mike G L Baillie ◽  
Edouard Bard ◽  
J Warren Beck ◽  
Chanda J H Bertrand ◽  
...  
Keyword(s):  
Tree Ring ◽  
Mixed Layer ◽  
Calibration Curve ◽  
Companion Paper ◽  
Data Sets ◽  
Calibration Data ◽  
Surface Mixed Layer ◽  
Radiocarbon Age ◽  
Tree Ring Data ◽  
Marine Data

New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration data sets extend an additional 2000 yr, from 0–26 cal kyr BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision, and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically-dated tree-ring samples, converted with a box diffusion model to marine mixed-layer ages, cover the period from 0–10.5 cal kyr BP. Beyond 10.5 cal kyr BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals. The marine records are corrected with site-specific 14C reservoir age information to provide a single global marine mixed-layer calibration from 10.5–26.0 cal kyr BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the 14C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring data sets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al. (this issue).

scholarly journals A 368-year maximum temperature reconstruction based on tree-ring data in the northwestern Sichuan Plateau (NWSP), China

2016 ◽  
Vol 12 (7) ◽  
pp. 1485-1498 ◽  
Author(s):  
Liangjun Zhu ◽  
Yuandong Zhang ◽  
Zongshan Li ◽  
Binde Guo ◽  
Xiaochun Wang
Keyword(s):  
Tree Ring ◽  
Land Surface ◽  
Temperature Reconstruction ◽  
Temperature Variability ◽  
Ice Age ◽  
Maximum Temperature ◽  
Tree Ring Data ◽  
The Mean ◽  
Extreme Cold ◽  
The 19Th Century

Abstract. We present a reconstruction of July–August mean maximum temperature variability based on a chronology of tree-ring widths over the period AD 1646–2013 in the northern part of the northwestern Sichuan Plateau (NWSP), China. A regression model explains 37.1 % of the variance of July–August mean maximum temperature during the calibration period from 1954 to 2012. Compared with nearby temperature reconstructions and gridded land surface temperature data, our temperature reconstruction had high spatial representativeness. Seven major cold periods were identified (1708–1711, 1765–1769, 1818–1821, 1824–1828, 1832–1836, 1839–1842, and 1869–1877), and three major warm periods occurred in 1655–1668, 1719–1730, and 1858–1859 from this reconstruction. The typical Little Ice Age climate can also be well represented in our reconstruction and clearly ended with climatic amelioration at the late of the 19th century. The 17th and 19th centuries were cold with more extreme cold years, while the 18th and 20th centuries were warm with less extreme cold years. Moreover, the 20th century rapid warming was not obvious in the NWSP mean maximum temperature reconstruction, which implied that mean maximum temperature might play an important and different role in global change as unique temperature indicators. Multi-taper method (MTM) spectral analysis revealed significant periodicities of 170-, 49–114-, 25–32-, 5.7-, 4.6–4.7-, 3.0–3.1-, 2.5-, and 2.1–2.3-year quasi-cycles at a 95 % confidence level in our reconstruction. Overall, the mean maximum temperature variability in the NWSP may be associated with global land–sea atmospheric circulation (e.g., ENSO, PDO, or AMO) as well as solar and volcanic forcing.

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