The School of Earth and Atmospheric Sciences Presents Dr. Sara Sanchez, University of Washington

Reconstructing the ENSO Response to the Mystery and Tambora Eruptions with Coral Based Data Assimilation 

Scientific understanding of low-frequency tropical Pacific variability suffers from short observational records, sparse proxy networks, and bias in model simulations. Here, we combine the strengths of proxies and models through coral-based paleoclimate data assimilation. 

We combine coral archives (δ18O, Sr/Ca) with the dynamics, spatial teleconnections, and intervariable relationships of the CMIP5/PMIP3 Past1000 experiments using the Last Millennium Reanalysis data assimilation framework. This analysis creates skillful reconstructions of tropical Pacific temperatures over the observational era. 

However, during the period of intense volcanism in the early 19th century, southwestern Pacific corals produce Nino 3.4 reconstructions that are at odds with reconstructions suggested from other proxies. We systematically evaluate the source of this discrepancy. 

We find that following major volcanic eruptions, the southwestern Pacific corals locally record more persistent cold anomalies than found in the Past1000 experiments and that canonical ENSO teleconnections to the southwest Pacific strongly control the reconstruction response.