Antarctic Ice Core Series
In recent years Antarctic Ice Cores have yielded estimates of atmospheric temperatures and carbon dioxide concentrations at several thousand points over the period in the past 800,000 years or so of Earth’s history. Our picture shows a typical ice core from which samples are taken at approximately equally spaced depths, every 0.55m. However, dating methods applied to the samples results in associated times which are highly irregularly spaced, due to varying deposition rates and compression.
Using the methods presented in Chapter 8 of the book, we have modelled these irregular time series, which are shown in Figure 2 of Luthi, D et al. Nature, 453, 379–382 and may be found using paleo-search . They may also be downloaded below. The file AGECO2EDC.txt has two colums of 1096 values, the first column being the time before present of the measurement, the second being the measurement of atmospheric carbon dioxide concentration in parts per million by volume. The file AGETEMPEDC.txt has two columns of 5788 values, the first being the time before present of the measurement, the second being the measurement of temperature in degrees Celsius. A bivariate model of this data is presented in the working paper GeophysicalTimeSeriesModelling and its supplement GeophysicalTimeSeriesModellingSupplement which are to appear in Environmetrics.