Multi-parameter Selection Curves for Machine-assisted Annual Layer Interpretations of the WAIS-Divide Core

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McGwire/1142164This award supports a project to extend a novel "selection curve" method that was developed to interpret annual layers in the West Antarctic Ice Sheet (WAIS) Divide ice core based on dielectric properties (DEP) to the analysis of ice core chemical measurements. The selection curve algorithm uses a spline curve whose shape selects successive annual peaks in plots of ice core parameters. Using 50 meters of manually interpreted calibration data, the selection curve method matched a manual interpretation throughout a 1200 m dataset to within 1% of the total count and 2% root-mean square error (RMSE). In this project the selection curve method will be enhanced to incorporate multiple chemical measurements derived from high-resolution continuous flow analysis (CFA) measurements of the WAIS Divide ice core and will include a number of indicators for the quality of annual peak selections. The intellectual merit of this project is that it will provide an objective, repeatable method for multi-parameter counting to support the development of the final WAIS Divide annually resolved timescale. This capability will improve the speed and end-to-end consistency of timescale development at WAIS Divide and in future studies. The ability to extract ice core information at sub-annual scales has the potential to greatly enrich the understanding of past climate regimes. This work will have broader impacts that benefit society because ice core science addresses critically important questions related to global warming, abrupt climate change, and biogeochemical cycling that will help to inform policy makers. By integrating an objective, repeatable multi-parameter counting tool into the final timescale development strategy at WAIS Divide, the proposed effort would reduce potential undue criticism of subjectivity in ice core interpretations and climate change science. The proposed analytical software will be made available to the broad community, improving scientific infrastructure, and could be used for non- ice core applications as well. This project does not require field-work in the Antarctic.