Interannual Southern California Precipitation Variability During the Common Era and the ENSO Teleconnection

Southern California's Mediterranean-type hydroclimate is highly variable on interannual time scales due to teleconnected climate forcings such as the El Niño–Southern Oscillation (ENSO). Here we present subannually resolved scanning X-ray fluorescence Ti counts from deep-sea cores in Santa Barbara Basin, California, recording 2,000 years of hydroclimate variability. The reconstructed Southern California precipitation record contains interannual variability in the 2- to 7-year band that could be driven by changes in tropical Pacific ENSO variability and/or the strength of the ENSO teleconnection modulated by extratropical pressure systems. Observed interannual precipitation variance increased and was associated with longer periodicities (5–7 years) when the Intertropical Convergence Zone migrated southward (1370–1540 CE) and the Aleutian Low strengthened creating a robust ENSO teleconnection. Weak interannual precipitation variance with shorter periodicity (2–3 years) was observed when the Intertropical Convergence Zone shifted northward (700–900 CE) and/or the Aleutian Low was weak (1540–1680 CE).