scholarly journals Matching Dendrochronological Dates with the Southern Hemisphere 14C Bomb Curve to Confirm Annual Tree Rings in Pseudolmedia rigida from Bolivia

Radiocarbon ◽  
2015 ◽  
Vol 57 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Laia Andreu-Hayles ◽  
Guaciara M Santos ◽  
David A Herrera-Ramírez ◽  
Javier Martin-Fernández ◽  
Daniel Ruiz-Carrascal ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Tree Rings ◽  
Geographic Location ◽  
Data Sets ◽  
Atmospheric Concentration ◽  
Concentration Data ◽  
Data Set ◽  
Dendrochronological Analysis ◽  
Before And After ◽  
Ring Analysis

This study used high-precision radiocarbon bomb-pulse dating of selected wood rings to provide an independent validation of the tree growth periodicity of Pseudolmedia rigida (Klotzsch & H. Karst) Cuatrec. from the Moraceae family, collected in the Madidi National Park in Bolivia. 14C content was measured by accelerator mass spectrometry (AMS) in 10 samples from a single tree covering over 70 yr from 1939 to 2011. These preliminary calendar dates were determined by dendrochronological techniques and were also used to select the samples for 14C AMS. In order to validate these preliminary dates using the established Southern Hemisphere (SH) 14C atmospheric concentration data set, the targeted rings were selected to be formed during periods before and after the 14C bomb spike nuclear tests (i.e. 1950s–1960s). The excellent agreement of the dendrochronological dates and the 14C signatures in tree rings associated with the same dates provided by the bomb-pulse 14C atmospheric values for the SH (SHCal zone 1–2) confirms the annual periodicity of the observed growth layers, and thus the high potential of this species for tree-ring analysis. The lack of discrepancies between both data sets also suggests that there are no significant latitudinal differences between the 14C SHCal zone 1–2 curve and the 14C values obtained from the selected tree rings at this geographic location (14°33′S, 68°49′W) in South America. The annual resolution of P. rigida tree rings opens the possibility of broader applications of dendrochronological analysis for ecological and paleoclimatic studies in the Bolivian tropics, as well as the possibility of using wood samples from some tree species from this region to improve the quality of the bomb-pulse 14C SHCal curve at this latitude.

scholarly journals High-Precision Radiocarbon Measurements of Tree-Ring Dated Wood from New Zealand: 195 Bc–Ad 995

Radiocarbon ◽  
2011 ◽  
Vol 53 (3) ◽  
pp. 529-542 ◽  
Author(s):  
Alan Hogg ◽  
Jonathan Palmer ◽  
Gretel Boswijk ◽  
Chris Turney
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Calibration Curve ◽  
Geographic Location ◽  
Temporal Variations ◽  
Time Interval ◽  
Data Sets ◽  
Data Set ◽  
Data Points ◽  
Lagarostrobos Franklinii

The best means for correcting Southern Hemisphere (SH) radiocarbon measurements, which are significantly influenced by temporal variations in the interhemispheric offset, is by the construction of a SH-specific calibration curve from dendrochronologically dated wood. We present here decadal 14C measurements on dendrochronologically secure New Zealand kauri (Agathis australis), covering the period 195 BC–AD 995, extending the range of calibration measurements from New Zealand tree rings to more than 2 millennia.Recently published Tasmanian huon pine (Lagarostrobos franklinii) data for the interval 165 BC to AD 1095 measured at the Center for Accelerator Mass Spectrometry (CAMS) have underestimated standard errors, which need to be re-assessed before the data can be considered for a Southern Hemisphere calibration curve update. The CAMS huon data, unlike the Waikato kauri data presented here, show a significant reduction in the SH offset for the interval AD 775–855. Although these data points are being checked, it is unlikely this represents a temporal geographic location-dependent offset. With re-assessed errors, the huon data set from 165 BC to AD 995 closely matches the new kauri data, with the combined data sets producing a mean interhemispheric offset with IntCal09 of 44 ± 17 yr for the time interval 195 BC–AD 1845. This SH offset is lower than the modeled offset of 55–58 yr used in the construction of SHCal04, and we recommend the lower value be used in future SHCal updates. Although there is an apparent increase in higher frequency events in the SH offset (NZ kauri plus Tasmanian huon) from 200 BC–AD 1000, the reason for this remains unclear.

Descriptive Statistics and Cross-National Comparisons of Arctic Power Projection

2020 ◽  
pp. 56-80
Author(s):  
Jonathan N. Markowitz
Keyword(s):  
Descriptive Statistics ◽  
The Arctic ◽  
Military Force ◽  
Data Sets ◽  
Data Set ◽  
Power Projection ◽  
Resource Rents ◽  
Before And After ◽  
Military Activity ◽  
Events Data

Chapter 4 employs data from three new data sets, the Arctic Military Activity Events Data Set, the Arctic Bases Data Set, and the Icebreaker and Ice-Hardened Warships Data Set. These new data enable a systematic comparison of each state’s Arctic military forces and deployments before and after the 2007 climate shock. The data offer a corrective to both sensationalist media accounts that suggest that all states are scrambling to fight over Arctic resources and those who downplay real changes in states’ Arctic military capabilities and presence. Confirming Rent-Addition’s Theory’s predictions, the descriptive statistical comparisons reveal that the states that were most economically dependent on resource rents, Norway and Russia, were the most willing to back their claims by projecting military force to disputed areas and investing in Arctic bases, ice-hardened warships, and icebreakers.

scholarly journals SCIAMACHY WFM-DOAS XCO<sub>2</sub>: comparison with CarbonTracker XCO<sub>2</sub> focusing on aerosols and thin clouds

2012 ◽  
Vol 5 (2) ◽  
pp. 2887-2931 ◽  
Author(s):  
J. Heymann ◽  
O. Schneising ◽  
M. Reuter ◽  
M. Buchwitz ◽  
V. V. Rozanov ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Temporal Correlation ◽  
Anthropogenic Activity ◽  
Data Sets ◽  
Spatial Correlations ◽  
Data Set ◽  
Cloud Data ◽  
Temporal Correlations ◽  
Retrieval Errors ◽  
The Difference

Abstract. Carbon dioxide (CO2) is the most important greenhouse gas whose atmospheric loading has been significantly increased by anthropogenic activity leading to global warming. Accurate measurements and models are needed in order to reliably predict our future climate. This, however, has challenging requirements. Errors in measurements and models need to be identified and minimised. In this context, we present a comparison between satellite-derived column-averaged dry air mole fractions of CO2, denoted XCO2, retrieved from SCIAMACHY/ENVISAT using the WFM-DOAS algorithm, and output from NOAA's global CO2 modelling and assimilation system CarbonTracker. We investigate to what extent differences between these two data sets are influenced by systematic retrieval errors due to aerosols and unaccounted clouds. We analyse seven years of SCIAMACHY WFM-DOAS version 2.1 retrievals (WFMDv2.1) using the latest version of CarbonTracker (version 2010). We investigate to what extent the difference between SCIAMACHY and CarbonTracker XCO2 are temporally and spatially correlated with global aerosol and cloud data sets. For this purpose, we use a global aerosol data set generated within the European GEMS project, which is based on assimilated MODIS satellite data. For clouds, we use a data set derived from CALIOP/CALIPSO. We find significant correlations of the SCIAMACHY minus CarbonTracker XCO2 difference with thin clouds over the Southern Hemisphere. The maximum temporal correlation we find for Darwin, Australia (r2 = 54%). Large temporal correlations with thin clouds are also observed over other regions of the Southern Hemisphere (e.g. 43% for South America and 31% for South Africa). Over the Northern Hemisphere the temporal correlations are typically much lower. An exception is India, where large temporal correlations with clouds and aerosols have also been found. For all other regions the temporal correlations with aerosol are typically low. For the spatial correlations the picture is less clear. They are typically low for both aerosols and clouds, but dependent on region and season, they may exceed 30% (the maximum value of 46% has been found for Darwin during September to November). Overall we find that the presence of thin clouds can potentially explain a significant fraction of the difference between SCIAMACHY WFMDv2.1 XCO2 and CarbonTracker over the Southern Hemisphere. Aerosols appear to be less of a problem. Our study indicates that the quality of the satellite derived XCO2 will significantly benefit from a reduction of scattering related retrieval errors at least for the Southern Hemisphere.

scholarly journals Comparison of 14C Ages Between LSC and AMS Measurements of Choukai Jindai Cedar Tree Rings at 2600 cal BP

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 895-900 ◽  
Author(s):  
Yui Takahashi ◽  
Hirohisa Sakurai ◽  
Kayo Suzuki ◽  
Taiichi Sato ◽  
Shuichi Gunji ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tree Rings ◽  
Liquid Scintillation ◽  
Measurement Methods ◽  
Scintillation Counting ◽  
Age Difference ◽  
Data Sets ◽  
Data Set ◽  
The Difference ◽  
Good Agreement

Radiocarbon ages of Choukai Jindai cedar tree rings growing in the excess era of 14C concentrations during 2757–2437 cal BP were measured using 2 types of 14C measurement methods, i.e. liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS). The difference between the 2 methods is 3.7 ± 5.2 14C yr on average for 61 single-year tree rings, indicating good agreement between the methods. The Choukai data sets show a small sharp bump with an average 14C age of 2497.1 ± 3.0 14C yr BP during 2650–2600 cal BP. Although the profile of the Choukai LSC data set compares well with that of IntCal04, having a 14C age difference of 4.6 ± 5.3 14C yr on average, the Choukai LSC 14C ages indicate variability against the smoothed profile of IntCal04.

scholarly journals An examination of the effect of the TESS extended mission on southern hemisphere monotransits

2019 ◽  
Vol 631 ◽  
pp. A83 ◽  
Author(s):  
Benjamin F. Cooke ◽  
Don Pollacco ◽  
Daniel Bayliss
Keyword(s):  
Southern Hemisphere ◽  
Large Time ◽  
First Year ◽  
Data Sets ◽  
Data Set ◽  
Window Functions ◽  
Time Gap ◽  
Initial Survey

Context. NASA recently announced an extended mission for TESS. As a result it is expected that the southern ecliptic hemisphere will be re-observed approximately two years after the initial survey. Aims. We aim to explore how TESS re-observing the southern ecliptic hemisphere will impact the number and distribution of monotransits discovered during the first year of observations. This simulation will be able to be scaled to any future TESS re-observations. Methods. We carry out an updated simulation of TESS detections in the southern ecliptic hemisphere. This simulation includes realistic Sector window-functions based on the first 11 sectors of SPOC 2 min SAP lightcurves. We then extend this simulation to cover the expected Year 4 of the mission when TESS will re-observe the southern ecliptic fields. For recovered monotransits we also look at the possibility of predicting the period based on the coverage in the TESS data. Results. We find an updated prediction of 339 monotransits from the TESS Year 1 southern ecliptic hemisphere, and that approximately 80% of these systems (266/339) will transit again in the Year 4 observations. The Year 4 observations will also contribute new monotransits not seen in Year 1, resulting in a total of 149 monotransits from the combined Year 1 and Year 4 data sets. We find that 75% (189/266) of recovered Year 1 monotransits will only transit once in the Year 4 data set. For these systems we will be able to constrain possible periods, but period aliasing due to the large time gap between Year 1 and Year 4 observations means that the true period will remain unknown without further spectroscopic or photometric follow-up.

ATMOSPHERIC RADIOCARBON FOR THE PERIOD 1950–2019

Radiocarbon ◽  
2021 ◽  
pp. 1-23
Author(s):  
Quan Hua ◽  
Jocelyn C Turnbull ◽  
Guaciara M Santos ◽  
Andrzej Z Rakowski ◽  
Santiago Ancapichún ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Rings ◽  
Data Sets ◽  
Previous Approach ◽  
Monthly Data ◽  
Smooth Curves ◽  
Clean Air ◽  
Increasing Demand

ABSTRACT This paper presents a compilation of atmospheric radiocarbon for the period 1950–2019, derived from atmospheric CO2 sampling and tree rings from clean-air sites. Following the approach taken by Hua et al. (2013), our revised and extended compilation consists of zonal, hemispheric and global radiocarbon (14C) data sets, with monthly data sets for 5 zones (Northern Hemisphere zones 1, 2, and 3, and Southern Hemisphere zones 3 and 1–2). Our new compilation includes smooth curves for zonal data sets that are more suitable for dating applications than the previous approach based on simple averaging. Our new radiocarbon dataset is intended to help facilitate the use of atmospheric bomb 14C in carbon cycle studies and to accommodate increasing demand for accurate dating of recent (post-1950) terrestrial samples.

scholarly journals A Synthesis of the Information Given by Temporal Data Series: The Representative Day

2021 ◽  
Author(s):  
Tiziano Tirabassi ◽  
Daniela Buske
Keyword(s):  
Air Pollution ◽  
Time Series ◽  
Least Squares ◽  
Data Series ◽  
Data Sets ◽  
Temporal Data ◽  
Concentration Data ◽  
Data Set ◽  
Meaningful Information ◽  
And Control

The recording of air pollution concentration values involves the measurement of a large volume of data. Generally, automatic selectors and explicators are provided by statistics. The use of the Representative Day allows the compilation of large amounts of data in a compact format that will supply meaningful information on the whole data set. The Representative Day (RD) is a real day that best represents (in the meaning of the least squares technique) the set of daily trends of the considered time series. The Least Representative Day (LRD), on the contrary, it is a real day that worst represents (in the meaning of the least squares technique) the set of daily trends of the same time series. The identification of RD and LRD can prove to be a very important tool for identifying both anomalous and standard behaviors of pollutants within the selected period and establishing measures of prevention, limitation and control. Two application examples, in two different areas, are presented related to meteorological and SO 2 and O 3 concentration data sets.

scholarly journals 14C Dating of ∼2500-Yr-Old Choukai Jindai Cedar Tree Rings from Japan Using Highly Accurate LSC Measurement

Radiocarbon ◽  
2006 ◽  
Vol 48 (3) ◽  
pp. 401-408 ◽  
Author(s):  
Hirohisa Sakurai ◽  
Wataru Kato ◽  
Yosuke Takahashi ◽  
Kayo Suzuki ◽  
Yui Takahashi ◽  
...  
Keyword(s):  
Tree Rings ◽  
Liquid Scintillation ◽  
Far East ◽  
Outer Edge ◽  
Data Sets ◽  
Calibration Data ◽  
Cellulose Sample ◽  
14C Dating ◽  
Data Set ◽  
The Far East

Radiocarbon ages of 8 decadal tree rings and 66 single-yr tree rings have been measured with a highly accurate liquid scintillation counting (LSC) system (0.2% error) after synthesizing 10.5 g of benzene for each α-cellulose sample produced from tree rings of Choukai Jindai cedar in Japan (39°N). The 14C ages were between 2449 and 2539 14C yr BP for the 21 samples. From the wiggle-matching of the data set using the IntCal04 (Reimer et al. 2004) calibration data in OxCal v 3.10 (Bronk Ramsey 2005), the estimated age of the outer edge of the Choukai tree rings was 477.5 BC (±12.5 yr) with a confidence level of 95.5%; hence, the Choukai tree rings range from 2757 to 2437 cal BP. The age indicates an improved eruption date of the Choukai Volcano. The statistical errors at 1 σ are approximately ± 10 and ± 7 14C yr for the 5-yr data and the decadal data from the single-yr measurements, respectively. For the interval between 2580 and 2520 cal BP, it is statistically significant that the Choukai 14C ages are ∼16 14C yr older on average than both the IntCal04 and QL German oak (∼50°N) data sets. The ∼2.0% offset is informative for the study of regional offset in the Far East.

scholarly journals 14C Age Measurements of Single-Year Tree Rings of Old Wood Samples 22,000 14C Years BP

Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 901-906 ◽  
Author(s):  
Taiichi Sato ◽  
Hirohisa Sakurai ◽  
Kayo Suzuki ◽  
Yui Takahashi
Keyword(s):  
Mass Spectrometry ◽  
Tree Rings ◽  
Periodic Variation ◽  
Data Sets ◽  
Weighted Mean ◽  
Data Set ◽  
Mean Values ◽  
14C Age ◽  
Combined Data ◽  
Sequential Measurements

Radiocarbon ages of single-year tree rings were measured for Kaminoyama wood samples using accelerator mass spectrometry (AMS) in 2 Japanese facilities, MALT and JAEA, in order to investigate the periodic variation of 14C concentrations relating to the 11-yr solar cycle near 26,000 yr BP. Eight sequential measurements of 14C ages were carried out for a set of 13 alternate single-year tree rings covering 26 yr. Averages of the 5 data sets in MALT and 3 data sets in JAEA were 22,146 ± 50 and 22,407 ± 58 14C yr BP, respectively, indicating an offset of 260 ± 77 14C yr. Multiple sequential measurements are advantageous for evaluating offsets. The standard deviation of the residuals of 14C ages from the averages in each data set was 118 14C yr, in contrast to that of 234 14C yr for the combined data sets due to an elimination effect in the offsets. The profiles of weighted mean values for the residuals of 14C ages showed similar enhancements with a width of ∼12 yr for measurements in the 2 facilities. This indicates the reproducibility of the multiple sequential measurements. In the profile for the combined 8 data sets, the 14C enhancement was 73 ± 36 14C yr from the average.

scholarly journals SHCal13 Southern Hemisphere Calibration, 0–50,000 Years cal BP

Radiocarbon ◽  
2013 ◽  
Vol 55 (4) ◽  
pp. 1889-1903 ◽  
Author(s):  
Alan G Hogg ◽  
Quan Hua ◽  
Paul G Blackwell ◽  
Mu Niu ◽  
Caitlin E Buck ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Calibration Curve ◽  
Younger Dryas ◽  
Autoregressive Process ◽  
Measured Data ◽  
Data Sets ◽  
Short Term ◽  
Data Set ◽  
Radiocarbon Calibration

The Southern Hemisphere SHCal04 radiocarbon calibration curve has been updated with the addition of new data sets extending measurements to 2145 cal BP and including the ANSTO Younger Dryas Huon pine data set. Outside the range of measured data, the curve is based upon the ern Hemisphere data sets as presented in IntCal13, with an interhemispheric offset averaging 43 ± 23 yr modeled by an autoregressive process to represent the short-term correlations in the offset.

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