Paleo data assimilation of coral δ18O Part 2: 20th century trends and variability of the tropical Pacific

Paleo data assimilation of coral δ18O Part 2: 20th century trends and variability of the tropical Pacific | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 18 December 2025 V1 Latest version Share on Paleo data assimilation of coral δ18O Part 2: 20th century trends and variability of the tropical Pacific Authors : Sara C Sanchez 0000-0002-1923-1218 [email protected] , Feng Zhu 0000-0002-9969-2953 , Casey Saenger , and Diane M. Thompson 0000-0002-6181-1259 Authors Info & Affiliations https://doi.org/10.22541/au.176607163.35046990/v1 108 views 160 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Limited instrumental observations have created uncertainties in the rates and patterns of historical variations in tropical sea-surface temperature, precipitation, and salinity. Coral archives are well suited to monitor past variations in the tropical oceans; in particular, the oxygen isotope composition (δ18O) has the unique potential to provide untapped insight into historic changes in the tropical hydrological cycle. We build upon Part 1 to emphasize the challenges and opportunities of using coral δ18O with the Last Millennium Ensemble paleoclimate data assimilation (paleo-DA) framework. We evaluate the sensitivity of our reconstructions to specific choices of paleo-DA components, such as climate model priors, coral δ18O proxy system models, and salinity calibration products, and reflect on the combination of methodological choices that are required to best incorporate coral δ18O with a paleo-DA approach. We then evaluate trends and variability across the global tropics, finding evidence for strengthening Walker Circulation and an intensification of the hydrological cycle. However, diagnosing the relative rates of warming across the equatorial Pacific is highly challenging, likely due to the high covariability of sea-surface temperature and salinity anomalies across the global tropics. We also find that the hydrological cycle response to ENSO has intensified and marginally shifted eastward over the 19th and 20th centuries. This work emphasizes a need for greater monitoring and improved simulations of δ18Osw and salinity, and illustrates the potential for using coral δ18O to evaluate past hydroclimate variability with paleo-DA. Supplementary Material File (1050362_0_merged_1760322036.pdf) Download 6.55 MB File (agu_manuscript_word_part2.docx) Download 5.01 MB File (agu_suppinfo_word_part2.docx) Download 5.20 MB Information & Authors Information Version history V1 Version 1 18 December 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords coral oxygen isotopes paleo-data assimilation paleoclimatology Authors Affiliations Sara C Sanchez 0000-0002-1923-1218 [email protected] University of Colorado Boulder View all articles by this author Feng Zhu 0000-0002-9969-2953 NSF National Center for Atmospheric Research View all articles by this author Casey Saenger Western Washington University View all articles by this author Diane M. Thompson 0000-0002-6181-1259 The University of Arizona View all articles by this author Metrics & Citations Metrics Article Usage 108 views 160 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Sara C Sanchez, Feng Zhu, Casey Saenger, et al. Paleo data assimilation of coral δ18O Part 2: 20th century trends and variability of the tropical Pacific. Authorea . 18 December 2025. DOI: https://doi.org/10.22541/au.176607163.35046990/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. 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