PP043-03
Best Practices for Coral Proxy-SST Calibration for 20th Century δ18Οsw Reconstruction – Initial Results from CoralHydro2k
Tuesday, 15 December 2020: 10:08
Virtual
Rachel Walter1, Hussein Sayani2, Kim Cobb2, Thomas Felis3, Nerilie J. Abram4, Jessica Hargreaves5, Kristine L DeLong6, Sarah Eggleston7, Bethany Ellis5, Nathalie Goodkin8, Kelly H Kilbourne9, Sujata A Murty10, Riovie Dela Pena Ramos11, Dhrubajyoti Samanta12, Sara C Sanchez13 and Feng Zhu14, (1)Georgia Institute of Technology Main Campus, Atlanta, GA, United States, (2)Georgia Institute of Technology Main Campus, Department of Earth and Atmospheric Sciences, Atlanta, GA, United States, (3)MARUM - Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany, (4)Australian National University, Research School of Earth Sciences, Canberra, Australia, (5)The Australian National University, Research School of Earth Sciences, Canberra, ACT, Australia, (6)Louisiana State University, Geography and Anthropology, Baton Rouge, LA, United States, (7)Past Global Changes, International Project Office, Bern, Switzerland, (8)American Museum of Natural History, New York, NY, United States, (9)University of Maryland (UMCES CBL), Solomons, MD, United States, (10)Woods Hole Oceanographic Institution, Woods Hole, MA, United States, (11)William Paterson University, Department of Environmental Science, Wayne, United States, (12)Nanyang Technological University, Singapore, Singapore, (13)Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, CA, United States, (14)University of Southern California, Department of Earth Sciences, Los Angeles, CA, United States
Abstract:
Coral archives are useful for resolving climate in the tropics where data from the 20th century and beyond is scarce or even nonexistent. Coral δ18O has been used to reconstruct combined changes in SST and hydrology in modern and fossil corals. Coral Sr/Ca records SST and is applied in conjunction with coral δ18O to isolate seawater δ18O (δ18Osw), an indicator of the local hydrological balance. As it stands, coral Sr/Ca-SST relationships are not consistent among sites, species, and sometimes even between corals on the same reef. Existing analyses are usually site specific, and individual studies employ various regression methods at different temporal resolutions (annual to monthly). Variability introduced by differing calculation methods integrates itself with existing natural coral variability, hampering efforts to effectively compare results among studies and compile information into a global picture.
Here, we present the new PAGES CoralHydro2k database, a collection of 45 paired coral Sr/Ca and δ18O records and 70 coral δ18O records. CoralHydro2k seeks to compile and leverage a large network of coral records to produce a reconstruction of hydrology for the last 200 years. We use this database to assess different combinations of SST products, temporal resolution, and regression methods to develop a consistent calibration framework to use as a set of “best practices” moving forward. Preliminary results suggest that annual-average calibrations begin to converge towards a common value across study sites, increasing their value for longer-term reconstructions. We also examine the sensitivity of δ18Osw to calibration methodology of paired Sr/Ca and δ18O records and discuss the implications of these and later findings in the context of paleo-δ18Osw reconstructions.
