![]() ![]() Argon isotopic data are therefore subject to the peculiar mathematics of 'compositional data', sensu Aitchison (1986, The Statistical Analysis of Compositional Data, Chapman & Hall). Thus, the 36 Ar, 39 Ar and 40 Ar abundances can be normalised to unity and plotted on a ternary diagram or 'simplex'. The age t does not depend on the absolute abundances of the three argon isotopes but only on their relative ratios. 40 Ar/39 Ar measurements are compositional dataIn its simplest form, the 40 Ar/39 Ar age equation can be written as: t = log(1+J )/λ = log(1 + JR)/λ Where λ is the 40K decay constant and J is the irradiation parameter. Ar-Ar_Redux is a new data reduction protocol and software program for 40 Ar/39 Ar geochronology which takes into account two previously underappreciated aspects of the method: 1. Rigorous data reduction and error propagation algorithms are needed to realise Earthtime's objective to improve the interlaboratory accuracy of 40 Ar/39 Ar dating to better than 1% and thereby facilitate the comparison and combination of the K- Ar and U-Pb chronometers. (Note, however, that old growth forests are not found within the WLEF tall tower flux footprint.)Īr-Ar_Redux: rigorous error propagation of 40 Ar/39 Ar data, including covariances Site was chosen to represent an end member representative of the upland forests in the WLEF tall tower flux footprint. Comparing net ecosystem exchange of carbon dioxide between an old-growth and mature forest in the upper midwest, USA. ![]() Note that a small lake to the north and data analyses suggest that wind direction screening is appropriate (see Desai, A.R., Bolstad, P.V., Cook, B.D., Davis, K.J., and Carey, E.V., 2005. Site Description - Old growth forest consisting primarily of sugar maple and eastern hemlock. This is the AmeriFlux version of the carbon flux data for the site US- Syv Sylvania Wilderness Area. AmeriFlux US- Syv Sylvania Wilderness Area ![]()
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