In the South Pacific Convergence Zone (SPCZ), interannual to interdecadal oceanic and atmospheric variability is especially pronounced. The El Niño Southern Oscillation and the Interdecadal Pacific Oscillation significantly influence the SPCZ diagonal axis and salinity front. Regional coral-based paleo-environmental reconstructions extend the relatively short and discontinuous instrumental sea surface temperature (SST) and sea surface salinity (SSS) record to elucidate past variability. We present monthly resolved, composite indices of coral skeletal δ18O, Sr/Ca, and calculated δ18Osw utilizing coral geochemical time-series from Rotuma, Fiji, Tonga, and Rarotonga, dubbed the SPCZcoral (SPCZc) indices. The new indices build upon previous efforts to describe variability and trends in the SPCZ region with expanded coverage due to a new northwestern coral addition from the SPCZ fresh pool. The increased spatial and temporal resolution of the new indices allows for higher-fidelity sub-annual reconstructions of SST and SSS in the region dating back to 1848. The results confirm the secular warming trend of 1°C in the SPCZ region and show a 0.4 Sp freshening starting in the 1880s. The SPCZc δ18Osw is the first regional reconstruction of δ18Osw and provides valuable insights into past SSS variability, including elucidating responses to El Niño and La Niña events, as well as identifying past SPCZ zonal events. The SPCZc δ18Osw reconstruction extends the instrumental records by ∼100 years. The SPCZc indices prove the utility of the compositing approach in describing regional oceanographic variability with the increased signal-to-noise ratio of the obtained coral climatic data.
Todorovic S., Linsley B.K., Kuhnert H., Dissard D., Menkes C. and Wu H. (2025) Expanded Composite Coral Indices of South Pacific Convergence Zone Oceanographic Variability Since 1848 CE. Paleoceanography and Paleoclimatology 40(5). 10.1029/2025PA005108
@article{Todorovic2025,
Title = {Expanded Composite Coral Indices of South Pacific Convergence Zone Oceanographic Variability Since 1848 CE},
Author = {Todorovic, Sara and Linsley, Braddock K. and Kuhnert, Henning and Dissard, Delphine and Menkes, Christophe and Wu, Henry},
Editor = {},
Journal = {Paleoceanography and Paleoclimatology},
Year = {2025},
Volume = {40},
Doi = {10.1029/2025PA005108},
Abstract = {In the South Pacific Convergence Zone (SPCZ), interannual to interdecadal oceanic and atmospheric variability is especially pronounced. The El Niño Southern Oscillation and the Interdecadal Pacific Oscillation significantly influence the SPCZ diagonal axis and salinity front. Regional coral-based paleo-environmental reconstructions extend the relatively short and discontinuous instrumental sea surface temperature (SST) and sea surface salinity (SSS) record to elucidate past variability. We present monthly resolved, composite indices of coral skeletal δ18O, Sr/Ca, and calculated δ18Osw utilizing coral geochemical time-series from Rotuma, Fiji, Tonga, and Rarotonga, dubbed the SPCZcoral (SPCZc) indices. The new indices build upon previous efforts to describe variability and trends in the SPCZ region with expanded coverage due to a new northwestern coral addition from the SPCZ fresh pool. The increased spatial and temporal resolution of the new indices allows for higher-fidelity sub-annual reconstructions of SST and SSS in the region dating back to 1848. The results confirm the secular warming trend of 1°C in the SPCZ region and show a 0.4 Sp freshening starting in the 1880s. The SPCZc δ18Osw is the first regional reconstruction of δ18Osw and provides valuable insights into past SSS variability, including elucidating responses to El Niño and La Niña events, as well as identifying past SPCZ zonal events. The SPCZc δ18Osw reconstruction extends the instrumental records by ∼100 years. The SPCZc indices prove the utility of the compositing approach in describing regional oceanographic variability with the increased signal-to-noise ratio of the obtained coral climatic data.},
}
TY - JOUR
AU - Todorovic, Sara
AU - Linsley, Braddock K.
AU - Kuhnert, Henning
AU - Dissard, Delphine
AU - Menkes, Christophe
AU - Wu, Henry
TI - Expanded Composite Coral Indices of South Pacific Convergence Zone Oceanographic Variability Since 1848 CE
T2 - Paleoceanography and Paleoclimatology
PY - 2025
VL - 40
DO - 10.1029/2025PA005108
AB - In the South Pacific Convergence Zone (SPCZ), interannual to interdecadal oceanic and atmospheric variability is especially pronounced. The El Niño Southern Oscillation and the Interdecadal Pacific Oscillation significantly influence the SPCZ diagonal axis and salinity front. Regional coral-based paleo-environmental reconstructions extend the relatively short and discontinuous instrumental sea surface temperature (SST) and sea surface salinity (SSS) record to elucidate past variability. We present monthly resolved, composite indices of coral skeletal δ18O, Sr/Ca, and calculated δ18Osw utilizing coral geochemical time-series from Rotuma, Fiji, Tonga, and Rarotonga, dubbed the SPCZcoral (SPCZc) indices. The new indices build upon previous efforts to describe variability and trends in the SPCZ region with expanded coverage due to a new northwestern coral addition from the SPCZ fresh pool. The increased spatial and temporal resolution of the new indices allows for higher-fidelity sub-annual reconstructions of SST and SSS in the region dating back to 1848. The results confirm the secular warming trend of 1°C in the SPCZ region and show a 0.4 Sp freshening starting in the 1880s. The SPCZc δ18Osw is the first regional reconstruction of δ18Osw and provides valuable insights into past SSS variability, including elucidating responses to El Niño and La Niña events, as well as identifying past SPCZ zonal events. The SPCZc δ18Osw reconstruction extends the instrumental records by ∼100 years. The SPCZc indices prove the utility of the compositing approach in describing regional oceanographic variability with the increased signal-to-noise ratio of the obtained coral climatic data.
ER -
