Huppert Amit

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Huppert
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Amit
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Now showing 1 - 4 of 4
  • Article
    On non-stationarity of ENSO
    (American Geophysical Union, 2003-09-13) Solow, Andrew R. ; Huppert, Amit
    Evolutionary spectral analysis has been used to study changes through time in the variability of ENSO-related time series. However, the significance of estimated evolutionary spectra has not been formally assessed. This paper describes a test for non-stationarity based on an estimate of the evolutionary spectrum and a time series bootstrap procedure. The test is applied to the seasonal time series of sea level pressure at Darwin. No significant non-stationarity is found.
  • Article
    Method for reconstructing climate from fossil beetle assemblages
    (Royal Society, 2004-04-19) Huppert, Amit ; Solow, Andrew R.
    Fossil beetle remains have been used to reconstruct temperatures. One method by which these reconstructions are made--the Mutual Climatic Range method--is based on the overlap of the observed modern climatic ranges of the beetles present in a fossil sample. A limitation of this method is that it does not exploit variations in the rate of occurrence of a species within its climatic range. We present an alternative method that uses observed variations in this rate in modern data for climate reconstruction. The method is shown to perform well in an experiment using modern data from North America.
  • Article
    Optimal multiproxy reconstruction of sea surface temperature from corals
    (American Geophysical Union, 2004-10-08) Solow, Andrew R. ; Huppert, Amit
    Past sea surface temperatures have been reconstructed using coral measurements of single geochemical proxies. There is some interest in improving reconstruction by combining results from different proxies. The construction of the optimal multiproxy reconstruction is described. The approach is illustrated using some data from New Caledonia.
  • Article
    A potential bias in coral reconstruction of sea surface temperature
    (American Geophysical Union, 2004-03-25) Solow, Andrew R. ; Huppert, Amit
    Isotopic measurements in corals are used to reconstruct past sea surface temperature. These reconstructions are based on calibration regression analyses using paired measurements of modern isotopic composition and sea surface temperature. It is shown that error in these measurements of sea surface temperature can lead to substantial bias in reconstruction. Provided the variance of the measurement error is known or can be estimated, a simple correction can eliminate this bias.