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Abstract:
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As a tree grows, the trunk diameter increases, and in a typical year, a tree-ring is produced. The width of this ring reflects growing conditions during the year -- when standardized, a wider ring indicates better growing conditions. Thus, tree-rings contain yearly climatic information, such as precipitation and temperature. Tree-ring records exist for thousands of years in many locations across the earth, and a goal of paleoclimatologists is to use these records to understand past climate. These records are related over space and time, but many explorations of the relationships among records tend to focus on either single element. We utilize the discrete wavelet transform to model record correlations with location and time-scale in a novel way, and a version of the wild bootstrap allows for error estimation. This model is demonstrated on a subset of Ponderosa pine records from the international tree-ring data bank (ITRDB) in the Four Corners states. We find a significant relationship with distance, but which also differs over different time scales.
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