<p> Models suggest that global warming will cause an intensification of the hydrologic cycle, but they are poor at predicting changes in the frequency of short, intense precipitation events at the regional to local scale. High-resolution stable isotope measurements across tree rings have shown potential for resolving precipitation at sub-annual resolution, but identification of single intense precipitation events across multiple tree rings has proven elusive. In this work, I report 218 high-resolution carbon isotope (δ<sup>13</sup>C) measurements made across eight growth rings of two Pinus trees cored in southern Louisiana. Tree rings were targeted for the presence and absence of extreme rainfall associated with land-falling tropical cyclones within 100 km of the study site. Comparison of the δ<sup>13</sup>C record to meteorological data yields a significant correlation (r = -0.576, p = 0.0004) with monthly precipitation and δ<sup>13</sup>C value measured across the rings. Significant, intra-ring declines of >1‰ are associated with monthly precipitation > 200 mm that cannot be resolved by low-resolution sampling. Comparing the effects of sample resolution on δ<sup>13</sup>C patterns suggests that wide-ringed samples are preferred for identifying precipitation events at sub-seasonal resolution. Recent technical and methodological advancements allow for more rapid preparation and analysis of intra-ring δ<sup> 13</sup>C data and provide opportunity for quantifying sub-seasonal environmental information within high-resolution tree-ring datasets. This work indicates the potential for quantifying changes in the magnitude and frequency of extreme precipitation events at individual sites from long-term intra-ring δ<sup> 13</sup>C records.</p><p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10682793 |
| Date | 03 May 2018 |
| Creators | Telus, Rose Guensly |
| Publisher | University of Louisiana at Lafayette |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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