Stochastic modelling of multi-grain equivalent dose (De) distributions: Implications for OSL dating of sediment mixtures   总被引：1，自引：0，他引：1  

L.J. Arnold  R.G. Roberts 《Quaternary Geochronology》2009,4(3):204-230

A number of recent optically stimulated luminescence (OSL) studies have cited post-depositional mixing as a dominant source of equivalent dose (D_e) scatter across a range of sedimentary environments, including those previously considered ‘best suited’ for OSL dating. The potentially insidious nature of sediment mixing means that this problem may often only be identifiable by careful statistical analysis of D_e data sets. This study aims to address some of the important issues associated with the characterisation and statistical treatment of mixed D_e distributions at the multi-grain scale of analysis, using simulated D_e data sets produced with a simple stochastic model. Using this Monte Carlo approach we were able to generate theoretical distributions of single-grain D_e values, which were then randomly mixed together to simulate multi-grain aliquot D_e distributions containing a known number of mixing components and known corresponding burial doses. A range of sensitivity tests were undertaken using sediment mixtures with different aged dose components, different numbers of mixing components, and different types of dose component distributions (fully bleached, heterogeneously bleached and significantly overdispersed D_e distributions). The results of our modelling simulations reveal the inherent problems encountered when dating mixed sedimentary samples with multi-grain D_e estimation techniques. ‘Phantom’ dose components (i.e. discrete dose populations that do not correspond to the original single-grain mixing components) are an inevitable consequence of the ‘averaging’ effects of multi-grain D_e analysis, and prevent the correct number of mixing components being identified with the finite mixture model (FMM) for all of the multi-grain mixtures tested. Our findings caution against use of the FMM for multi-grain aliquot D_e data sets, even when the aliquots consist of only a few grains.  相似文献   

Review on observational studies of western tropical Pacific Ocean circulation and climate     

Hu  Dunxin  Wang  Fan  Sprintall  Janet  Wu  Lixin  Riser  Stephen  Cravatte  Sophie  Gordon  Arnold  Zhang  Linlin  Chen  Dake  Zhou  Hui  Ando  Kentaro  Wang  Jianing  Lee  Jae-Hak  Hu  Shijian  Wang  Jing  Zhang  Dongxiao  Feng  Junqiao  Liu  Lingling  Villanoy  Cesar  Kaluwin  Chalapan  Qu  Tangdong  Ma  Yixin 《中国海洋湖沼学报》2020,38(4):906-929

The Western Tropical Pacific(WTP) Ocean holds the largest area of warm water(28℃) in the world ocean referred to as the Western Pacific Warm Pool(WPWP),which modulates the regional and global climate through strong atmospheric convection and its variability.The WTP is unique in terms of its complex 3-D ocean circulation system and intensive multiscale variability,making it crucial in the water and energy cycle of the global ocean.Great advances have been made in understanding the complexity of the WTP ocean circulation and associated climate impact by the international scientific community since the 1960 s through field experiments.In this study,we review the evolving insight to the 3-D structure and multi-scale variability of the ocean circulation in the WTP and their climatic impacts based on in-situ ocean observations in the past decades,with emphasis on the achievements since 2000.The challenges and open que stions remaining are reviewed as well as future plan for international study of the WTP ocean circulation and climate.  相似文献   

Reply to the comments on “The biosphere: A homogenizer of Pb-isotope signals” by Richard Bindler and William Shotyk     

Clemens Reimann  Belinda Flem  Arnold Arnoldussen  Peter Englmaier  Tor Erik Finne  Friedrich Koller   ystein Nordgulen 《Applied Geochemistry》2008,23(8):2527-2535

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The biosphere: A homogeniser of Pb-isotope signals     

Clemens Reimann  Belinda Flem  Arnold Arnoldussen  Peter Englmaier  Tor Erik Finne  Friedrich Koller  Øystein Nordgulen 《Applied Geochemistry》2008

Rock, soil, and plant (terrestrial moss, European mountain ash leaves, mountain birch leaves, bark and wood, and spruce needles and wood) samples, collected at 3 km intervals along a 120 km long transect (40 sites) cutting the city of Oslo, Norway, were analysed for their Pb concentration and Pb-isotope ratios. A general decrease in ²⁰⁶Pb/²⁰⁷Pb, ²⁰⁸Pb/²⁰⁷Pb and ²⁰⁶Pb/²⁰⁸Pb ratios, with a characteristic low variability in all plant materials and the plant-derived O-horizon of soil profiles, compared to rocks and mineral soils, is observed along the transect. It is demonstrated that minerogenic and biogenic sample materials belong to two different spheres, the lithosphere and biosphere, and that geochemical processes determining their chemical and isotopic compositions differ widely. Background variation for both sample materials needs to be established and documented at the continental and global scale before the anthropogenic influence on the geochemistry of the earth’s surface can be reliably estimated.  相似文献   

A comparison of the climatology of a tropospherestratosphere-mesosphere model with observations     

Steven Pawson  Ulrike Langematz  Arnold Meyer  Peter Strauch  Silke Leder  Klaus Rose 《Climate Dynamics》1991,5(3):161-174

Mean fields from a perpetual January simulation of a GCM extending from the surface to 0.01 hPa (near 80 km) are compared to observations. The zonal mean temperature and wind fields correspond quite well with reality; the low stratosphere, especially in the polar night, is too cold, but warmer than in the original version of the model, with an upper boundary at 25 hPa. Mean fields at standard levels show that the major features of the troposphere are represented by the model, but rather over emphasised; the stratospheric winter polar vortex is too strong, too cold, and too barotropic; it resembles an `undisturbed' January rather than the climatology. Differences in the stationary eddy activity between the extended and orginal versions of the model are noted, and used to explain some differences between the two simulations.This paper was presented at the International Conference on Modelling of Global Climate Change and Variability, held in Hamburg 11–15 September 1989 under the auspices of the Meteorological Institute of the University of Hamburg and the Max Planck Institute für Meteorology. Guest Editor for these papers is Dr. L. Dümenil  相似文献   

Das Problem der Kreide -Nummuliten in Ostschweiz und Vorarlberg     

Heim  Arnold 《International Journal of Earth Sciences》1924,15(3):223-226

International Journal of Earth Sciences -  相似文献   

Beobachtungen über die Entstehung der tertiären Kohlen (Humolithe und Saprohumolithe) in Zentralsumatra     

Arnold Heim  Robert Potonié 《International Journal of Earth Sciences》1932,23(3-4):145-172

Ohne Zusammenfassung  相似文献   

Neuere Veröffentlichungen     

Joachim Joseph  M. Rodewald  Arnold Schumacher  A. Schumacher 《Ocean Dynamics》1953,6(4-6):230-235

Ohne Zusammenfassung  相似文献   

Vertical movements of cod (Gadus morhua L.) in the open sea and the hydrostatic function of the swimbladder     

Arnold  G. P.; Walker  M. Greer 《ICES Journal of Marine Science》1992,49(3):357-372

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Suspended matter in the Caribbean Sea: A gravimetric analysis     

N.Jay BassinJohn E. Harris  Arnold H. Bouma 《Marine Geology》1972

Total suspended matter in the water column of the Caribbean was determined quantitatively by means of filtration through 0.45 μ membrane filters. Results show that prior values obtained by centrifuging methods are too low, and that the existence of a nepheloid layer cannot be gravimetrically demonstrated in the Caribbean.  相似文献