EGU25-12738, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-12738
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Water Isotopologue Time Series across Tropical Sites during ENSO extremes
Lucinda Bryce1, Kim Cobb1, Jessica Conroy2, Samantha Levin1, Manlin Xu3, Germain Hernández4, Ricardo Sánchez-Murillo5, Madeleine Hardt6, Nicole Murray2, Elisabeth Holland7, Wendy-Jane Powell8, Xi-Kai Wang1, and Syria Lejau9
Lucinda Bryce et al.
  • 1Brown University, Earth, Environmental, and Planetary Science, United States of America (lucinda_bryce@brown.edu)
  • 2University of Illinois at Urbana Champaign, Department of Earth Science & Environmental Change, Urbana, United States
  • 3Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology 77 Massachusetts Avenue, Cambridge, MA 02139
  • 4Stable Isotope Research Group and Water Resources Management Laboratory , Universidad Nacional Costa Rica, Heredia, 86-3000, Costa Rica
  • 5Department of Earth and Environmental Sciences, University of Texas at Arlington, 500 Yates Street, Arlington, 76019, TX, United States
  • 6Hawaii Institute of Marine Biology, University of Hawaii at Manoa, PO Box 1346, Kaneohe, Hawaii 96744, USA
  • 7Institute for Strategy, Resilience and Security, University College London, London, UK
  • 8Pacific Centre for Environment and Sustainable Development (PACE-SD), University of the South Pacific, Suva, Fiji
  • 9Gunung Mulu National Park, Sarawak, Malaysia

Potential anthropogenic shifts in the hydroclimate impacts of El Niño Southern Oscillation (ENSO) extremes are poorly resolved by available data. Water isotopologues provide valuable tracers of hydroclimatic processes, including the balance of precipitation versus evaporation and the relative importance of regional versus local drivers of hydroclimate variability  (Dee et al., 2023 and references therein; Moerman et al., 2013). However, very few water isotopologue datasets exist in the tropical Pacific, and those that do fail to resolve a full ENSO cycle. In this study, we present oxygen isotope (δ18O) and deuterium (δ2H) time series for precipitation, seawater, as well as sea-surface salinity time series from 5 sites spanning the tropical Pacific across the 2023/24 El Niño event and 2024/25 La Nina event.. Weekly seawater and daily rainwater δ18O time series from the Galapagos, Fiji, Hawaii, and Kiritimati Island, as well as rainwater δ18O time series from northern Borneo and Costa Rica reveal a distinct signature of the 2023/24 El Niño event. Preliminary analyses indicate that seawater δ18O values reflect both local and remote processes, with the relative balance being largely site-dependent. This study provides quantitative estimates of rainfall and seawater δ18O anomalies through a cycle of ENSO extremes, and investigates regional drivers of hydrologic circulation across space and time. Taken together, our results provide the first empirical dataset of ENSO-related δ18O anomalies spanning the tropical Pacific across a complete ENSO cycle, with applications to data-model intercomparison studies and investigations of tropical Pacific hydroclimatic processes. 

How to cite: Bryce, L., Cobb, K., Conroy, J., Levin, S., Xu, M., Hernández, G., Sánchez-Murillo, R., Hardt, M., Murray, N., Holland, E., Powell, W.-J., Wang, X.-K., and Lejau, S.: Water Isotopologue Time Series across Tropical Sites during ENSO extremes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12738, https://doi.org/10.5194/egusphere-egu25-12738, 2025.