Estimate Rates of Change – Continuous approach
The iceTEA tool estimates continuous rates of change for exposure age data in a horizontal or vertical transect, principally designed for rates of ice margin retreat and thinning. Fourier Series analysis is used to derive a retreat/thinning profile and corresponding rates. The results can then be plotted, with or without the exposure ages. An improved fit could be achieved with the more robust spline-based method, which is available as MATLAB© and R© code here.
Details are described here: Jones et al., 2019, Quaternary Geochronology (preprint version here).
Upload exposure age data in the ‘standard’ input form (as .xlsx, .csv or .txt), including previously calculated exposure ages. Input data in columns 8-15 are not essential for this analysis, and columns 2-6 are not required for a horizontal transect; zeros can be used for these columns. Then select whether the sample transect is horizontal or vertical, and choose the number of terms in the Fourier Series analysis (the more terms, the more sinusoidal the fit). The number of terms that can be used is dependent on the number of samples in the transect (for a smaller dataset, try a lower number of terms).