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).