IAI-ScientificArticles-CRN_003_Darrigo_ENSO: On the Variability of ENSO Over the Past Six Centuries

The instrumental record is too brief for evaluation of the El
Nino-Southern Oscillation (ENSO) system and its long-term response to climate
forcing. To supplement these data, we use a new reconstruction of
December-February Nino-3 sea surface temperatures based on subtropical North
American tree-ring records to investigate aspects of ENSO variability over the
past six centuries (AD 1408-1978). Spectral analyses reveal that the
reconstruction best resolves variability within the "classical" ENSO band of
2-8 years. A period of low amplitude variability in the 17th to 18th centuries
broadly coincides with "Little Ice Age" conditions over much of the globe. The
detailed behavior shows good agreement with other shorter reconstructions of
ENSO over the past few centuries, but shows mixed results with recent model
simulations of past ENSO behavior. We discuss possible reasons for these
discrepancies. CRN003, PI Dr. Brian Luckman.