Thomas E WoodruffPurdue University West Lafayette | Purdue · Department of Physics
Thomas E Woodruff
PhD
About
26
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Introduction
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Publications
Publications (26)
Between 15 and 27 kyr b2k (thousands of years before 2000 CE) during the last glacial, Greenland experienced a prolonged cold stadial phase, interrupted by two short-lived warm interstadials. Greenland ice-core calcium data show two periods, preceding the interstadials, of anomalously high atmospheric dust loading, the origin of which is not well u...
Between 15 and 27 ka b2k (thousands of years before 2000 CE) during the last glacial, Greenland experienced a prolonged cold stadial phase, interrupted by two short-lived warm interstadials. Greenland ice-core calcium data show two periods, preceding the interstadials, of anomalously high atmospheric dust loading, the origin of which is not well un...
Reference materials are key for assessing inter-laboratory variability and measurement quality, and for placing analytical uncertainty bounds on sample analyses. Here, we investigate four years of data resulting from repeated processing of the CRONUS-N reference material for cosmogenic ¹⁰Be and ²⁶Al analyses. At University of Vermont, we prepared a...
Analysis of the in situ produced cosmogenic nuclides ¹⁰Be and ²⁶Al has been used for several decades to study Earth surface processes; yet, no reference material has been widely adopted and used by the community to ensure the quality and comparability of sample preparation and isotopic analyses. Such a reference material could facilitate inter-labo...
Constraining the response time of the climate system to changes in North Atlantic Deep Water (NADW) formation is fundamental to improving climate and Atlantic Meridional Overturning Circulation predictability. Here we report a new synchronization of terrestrial, marine, and ice-core records, which allows the first quantitative determination of the...
The assumed value for the cosmogenic 26Al/10Be surface production rate ratio in quartz is an
important parameter for studies investigating the burial or subaerial erosion of long-lived surfaces and
sediments. Recent models and data suggest that the production ratio is spatially variable and may be greater
than originally thought. Here we present me...
We present the WD2014 chronology for the
upper part (0–2850 m; 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS)
Divide (WD) ice core. The chronology is based
on counting of annual layers observed in the chemical, dust and electrical
conductivity records. These layers are caused by seasonal changes in the
source, transport, and deposition of aeros...
The origin of two large peaks in the atmospheric radiocarbon ((14)C) concentration at AD 774/5 and 993/4 is still debated. There is consensus, however, that these features can only be explained by an increase in the atmospheric (14)C production rate due to an extraterrestrial event. Here we provide evidence that these peaks were most likely produce...
We present the WD2014 chronology for the upper part (0–2850 m, 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS) Divide ice core. The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposition of aerosols....
Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropi...
The last glacial period exhibited abrupt Dansgaard-Oeschger climatic oscillations, evidence of which is preserved in a variety of Northern Hemisphere palaeoclimate archives. Ice cores show that Antarctica cooled during the warm phases of the Greenland Dansgaard-Oeschger cycle and vice versa, suggesting an interhemispheric redistribution of heat thr...
To improve sample processing efficiency for cosmogenic radionuclide measurements in samples from the West Antarctic Ice Sheet Divide core, two chemical lines, one at Purdue University and one at the University of California, Berkeley, are being used. Sections from two shallow ice cores from West Antarctica were processed at each lab, while all 10Be...
Annual ice layers archive the cosmogenic radionuclide 10Be, which is in
turn an important proxy for solar activity, complementary to the 14C
tree ring archive. Although production is primarily determined by the
strength of the solar magnetic field 10Be deposition is also determined
by local weather phenomena and snow accumulation rates, especially...
Concentrations of cosmogenic 10Be in polar ice samples are a function of
variations in solar activity, geomagnetic field strength, atmospheric
mixing and annual snow accumulation rates. The 10Be depth profile in ice
cores also provides independent chronological markers to tie Antarctic
to Greenland ice cores and to tie Holocene ice cores to the 14C...
Questions
Question (1)
We have a gridded gas ionization detector with P-10. Cathode voltage is .5-1 V/cmTorr with anode voltage three times higher. The grid was designed according to Bunemann. We have a severe pulse height deficit (30-50%). Does anyone know what our problem might be? I think that our field is high enough to prevent recombination, the grid should be >95% transparent and with an electron collection time of 1 us decay time shouldn't be a problem. What am I missing?
