scholarly journals Resource polygon geometry predicts Bayesian stable isotope mixing model bias

2014 ◽  
Vol 514 ◽  
pp. 1-12 ◽  
Author(s):  
MT Brett
Keyword(s):  
Stable Isotope ◽  
Mixing Model ◽  
Model Bias ◽  
Stable Isotope Mixing Model

scholarly journals Selecting the best stable isotope mixing model to estimate grizzly bear diets in the Greater Yellowstone Ecosystem

PLoS ONE ◽  
2017 ◽  
Vol 12 (5) ◽  
pp. e0174903 ◽  
Author(s):  
John B. Hopkins ◽  
Jake M. Ferguson ◽  
Daniel B. Tyers ◽  
Carolyn M. Kurle
Keyword(s):  
Stable Isotope ◽  
Mixing Model ◽  
Greater Yellowstone Ecosystem ◽  
Grizzly Bear ◽  
Greater Yellowstone ◽  
Stable Isotope Mixing Model

scholarly journals Use of isotopic tungsten tracers and a stable-isotope-mixing model to characterize divertor source location in the DIII-D metal rings campaign

2019 ◽  
Vol 19 ◽  
pp. 358-363 ◽  
Author(s):  
E.A. Unterberg ◽  
D.C. Donovan ◽  
J.D. Duran ◽  
P.C. Stangeby ◽  
S. Zamperini ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Source Location ◽  
Mixing Model ◽  
Metal Rings ◽  
Stable Isotope Mixing Model

scholarly journals Water stable isotopes spatio-temporal variability in Antarctica in 1960–2013: observations and simulations from the ECHAM5-wiso atmospheric general circulation model

2017 ◽  
Author(s):  
Sentia Goursaud ◽  
Valérie Masson-Delmotte ◽  
Vincent Favier ◽  
Anaïs Orsi ◽  
Martin Werner
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
General Circulation ◽  
Atmospheric General Circulation Model ◽  
Ice Core ◽  
Circulation Model ◽  
Model Bias ◽  
Model Data ◽  
Atmospheric General Circulation ◽  
Water Stable Isotope

Abstract. Polar ice core water isotope records are commonly used to infer past changes in Antarctic temperature, motivating an improved understanding and quantification of the temporal relationship between δ18O and temperature. This can be achieved using simulations performed by atmospheric general circulation models equipped with water stable isotopes. Here, we evaluate the skills of the high resolution water-isotope-enabled atmospheric general circulation model ECHAM5-wiso (the European Centre Hamburg Model), nudged to European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis using simulations covering the period 1960–2013 over the Antarctic continent. We compare model outputs with field data, first with a focus on regional climate variables and, second on water stable isotopes, using our updated dataset of water stable isotope measurements from precipitation, snow and firn/ice core samples. ECHAM5-wiso simulates a large increase in temperature from 1978 to 1979, possibly caused by a discontinuity in the European Reanalyses (ERA) linked to the assimilation of remote sensing data starting in 1979. The comparison with accumulation and water stable isotope data is thus restricted to the period 1979–2013, for accumulation and water stable isotope data from snow and firn/ice core. Such a restriction was not decided for the isotopic composition from precipitation data that consist in a few number of points. For this comparison, we used outputs corresponding to the same exact days of observations, even if it was before 1979. Although some model-data mismatches are observed, the (precipitation minus evaporation) outputs are found to be realistic products for surface mass balance. A warm model bias over Central East Antarctica and a cold model bias over coastal regions explain first-order δ18O model biases by too strong isotopic depletion on coastal areas and underestimated depletion inland. At the second order, despite these biases, ECHAM5-wiso correctly captures the observed spatial and seasonal patterns of δ18O. The results of model-data comparisons for the inter-annual δ18O standard deviation differ when using precipitation or ice core data. Further studies should explore the importance of deposition and post-deposition processes affecting ice core signals and not resolved in the model. Despite systematic offsets, the increase of deuterium excess from coastal to inland regions is well simulated by the model. These results build trust in the use of ECHAM5-wiso outputs to investigate the spatial, seasonal and inter-annual δ18O-temperature relationships. We show that local spatial or seasonal slopes are not a correct surrogate for inter-annual temporal slopes, leading to the conclusion that a stationary isotope-temperature slope cannot be applied for the climatic interpretation of Antarctic ice core. We finally explore the phasing between the seasonal cycles of deuterium excess and δ18O, as a source of information on changes in moisture sources affecting the δ18O-temperature relationship. The few available records and ECHAM5-wiso show different phase relationships in coastal, intermediate and central regions. This work valuates the use of the ECHAM5-wiso model as a tool for the investigation of water stable isotopes in Antarctic precipitation, and calls for extended studies to improve our understanding of such proxies.

scholarly journals Comparisons of stable isotope (C, H, N) signatures for revealing organic matter sources and trophic relationships in headwater streams

2017 ◽  
Vol 74 (12) ◽  
pp. 2110-2121 ◽  
Author(s):  
Henry M. Page ◽  
Scott D. Cooper ◽  
Sheila W. Wiseman ◽  
Danuta Bennett ◽  
Kristie Klose ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Hydrogen Isotope ◽  
Southern California ◽  
Headwater Streams ◽  
Isotope Ratios ◽  
Mixing Model ◽  
Gut Contents ◽  
Stable Carbon ◽  
Predator Diet ◽  
Hydrogen Isotope Ratios

We compared the efficacy of stable carbon, hydrogen, and nitrogen isotope ratios in identifying the resources used by insect consumers in headwater streams of southern California. We also compared gut contents with consumer stable isotope ratios and mixing model estimates of resource contributions to predator diet. Stable hydrogen isotope ratios (as δ2H) of algivores were well separated from ratios for detritivores, whereas relationships between stable carbon (as δ13C) and nitrogen (as δ15N) ratios of consumers and their expected diets were weaker and more ambiguous. δ2H values of primary consumers more strongly reflected the proportions of their gut contents consisting of algae than δ13C values. Τhe proportions of algivorous prey in predator gut contents increased with mixing model estimates of algivore contributions to predator diet using δ2H but not δ13C values. Our findings support the use of hydrogen isotope ratios in food web studies of streams in southern California and their potential use in assessing the effects of anthropogenic and natural disturbance on basal resource contributions to food webs that might not otherwise be identified using carbon isotope ratios.

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