Variability of Monthly Radiocarbon During the 1760S in Corals from the Galapagos Islands

From the 18th International Radiocarbon Conference held in Wellington, New Zealand, September 1-5, 2003.Radiocarbon (∆14C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average ∆14C value of -62 is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760-1771 (+/6 yr). High ∆14C values were found during January through March, when upwelling was weak or absent at the Galapagos Islands. Low ∆14C values were obtained mid-year during strong upwelling. The average seasonal variability of ∆14C was 15-25 ppm, which is greater than that at other tropical and subtropical locations in the Pacific Ocean because of intense seasonal upwelling at this site. Periods of sustained high ∆14C values were found during 1762-1763 and 1766. A spectral analysis revealed that the spectral density for the ∆14C data displays most of its variance at the 5-yr cycle, which is reflective of El Niño periodicity during the 20th century.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Seasonal variations in the Amazon plume-related atmospheric carbon sink

The Amazon River plume is a highly seasonal feature that can reach more than 3000 km across the tropical Atlantic Ocean, and cover ∼2 million km². Ship observations show that its seasonal presence significantly reduces sea surface salinity and inorganic carbon. In the western tropical North Atlantic during April–May 2003, plume-influenced stations exhibited surface DIC concentrations lowered by as much as 563 μmol C kg⁻¹ (∼28%) and pCO₂ as low as 201 μatm. We combine our data with other data sets to understand the annual uptake and seasonal variability of the plume-related CO₂ sink. Using flux estimates from all seasons with monthly plume areas determined by satellite, we calculate the annual carbon uptake by the outer plume alone (28 < S < 35) to be 15 ± 6 TgC yr⁻¹. Diazotroph-supported net community production enhanced the air-sea CO₂ disequilibrium by 100x and reversed the typical CO₂ outgassing from the tropical North Atlantic. The carbon sink in the Amazon plume depends on climate-sensitive conditions that control river hydrology, CO₂ solubility, and gas exchange

FOXES AND HEDGEHOGS: BUILDING RANGE IN 21ST CENTURY COMMANDERS

In this thesis, I study how the Marine Corps is developing and selecting leaders who will promote innovation and success in the future battlefields. Several studies have analyzed the effects of graduate education and the factors associated with selection for promotion and command selection, but none have separated the Graduate Education Program (GEP) into areas of training and education. Prior research shows that Marine officers with non-professional military education (non-PME) graduate degrees (taught how to think) have lower performance, retention, and promotion rates than Marines at the same career point who attend a PME course (taught what to think). Since the institution of the Commandant’s Career-Level Education Board and Commandant’s Professional Intermediate-Level Education Board in 2011, the Marine Corps has redirected its best and brightest to attend a graduate-level institution. In this thesis, I use both quantitative and qualitative data to examine how GEP participation affects selection on the lieutenant colonel (LtCol) command screening board. I find that the timing of a Marine’s attendance to PME and non-PME GEPs is highly correlated to LtCol command selection, but does not currently predict command performance. Finally, I deduce that the Industrial Age model of education currently utilized by the Marine Corps will be ineffective in developing the interdisciplinary critical thinkers that will be needed for success in 21st century warfare.Outstanding ThesisMajor, United States Marine CorpsApproved for public release. Distribution is unlimited

Learning for Warfighters: A Conversation with Major General William F. Mullen III (ret.)

The article of record as published may be found at http://cimsec.org/learning-for-warfighters-a-conversation-with-major-general-william-f-mullen-iii-ret

Variability of radiocarbon during the 1760s in monthly corals from the Galapagos Islands

. Radiocarbon (∆14C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average ∆14C value of –62‰ is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760–1771 (±6 yr). High ∆14C values were found during January through March, when upwelling was weak or absent at the Galapagos Islands. Low ∆14C values were obtained mid-year during strong upwelling. The average seasonal variability of ∆14C was 15–25‰, which is greater than that at other tropical and subtropical locations in the Pacific Ocean because of intense seasonal upwelling at this site. Periods of sustained high ∆14C values were found during 1762–1763 and 1766. A spectral analysis revealed that the spectral density for the ∆14C data displays most of its variance at the 5-yr cycle, which is reflective of El Niño periodicity during the 20th century

Variability of radiocarbon during the 1760s in monthly corals from the Galapagos Islands

. Radiocarbon (∆14C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of California, Irvine. An average ∆14C value of –62‰ is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760–1771 (±6 yr). High ∆14C values were found during January through March, when upwelling was weak or absent at the Galapagos Islands. Low ∆14C values were obtained mid-year during strong upwelling. The average seasonal variability of ∆14C was 15–25‰, which is greater than that at other tropical and subtropical locations in the Pacific Ocean because of intense seasonal upwelling at this site. Periods of sustained high ∆14C values were found during 1762–1763 and 1766. A spectral analysis revealed that the spectral density for the ∆14C data displays most of its variance at the 5-yr cycle, which is reflective of El Niño periodicity during the 20th century

Variability of monthly radiocarbon during the 1760s in corals from the Galapagos Islands

Radiocarbon (Delta(14)C) measurements of monthly samples from a Galapagos surface coral are among the first data sets from the new Keck Carbon Cycle Accelerator Mass Spectrometry laboratory at the University of Califomia, Irvine. An average Delta(14)C value of -62parts per thousand is obtained for 144 measurements of samples from monthly coral bands that lived from about AD 1760-1771 (+/-6 yr). High Delta(14)C values were found during January through March, when upwelling was weak or absent at the Galapagos Islands. Low Delta(14)C values were obtained mid-year during strong upwelling. The average seasonal variability of Delta(14)C was 15-25parts per thousand, which is greater than that at other tropical and subtropical locations in the Pacific Ocean because of intense seasonal upwelling at this site. Periods of sustained high Delta(14)C values were found during 1762-1763 and 1766. A spectral analysis revealed that the spectral density for the Delta(14)C data displays most of its variance at the 5-yr cycle, which is reflective of El Nino periodicity during the 20th century.X1118sciescopu

The Keck Carbon Cycle AMS laboratory, University of California, Irvine: Initial operation and a background surprise

A new radiocarbon accelerator mass spectrometry (AMS) laboratory for carbon cycle studies has been established at the University of California, Irvine. The 0.5MV AMS system was installed in mid-2002 and has operated routinely since October of that year. This paper briefly describes the spectrometer and summarizes lessons learned during the first year of operation. In the process of setting up the system, we identified and largely suppressed a previously unreported C-14 AMS background: charge exchange tails from N-14 beams derived from nitrogen-containing molecular ions produced near the entrance of the accelerator