High-resolution interannual precipitation reconstruction of Southern California: Implications for Holocene ENSO evolution

Du, Xiaojing

High-resolution interannual precipitation reconstruction of Southern California: Implications for Holocene ENSO evolution

Thursday, 3 December 2020: 08:07

Xiaojing Du, Brown University, Earth and Environmental Sciences, Providence, RI, United States, Ingrid L Hendy, University of Michigan Ann Arbor, Earth and Environmental Sciences, Ann Arbor, MI, United States, Linda A Hinnov, George Mason University Fairfax, Fairfax, VA, United States, Erik Thorson Brown, University of Minnesota Duluth, Earth and Environmental Sciences Department, Duluth, MN, United States, Jiang Zhu, University of Michigan, Department of Earth and Environmental Science, Ann Arbor, United States and Christopher J Poulsen, University of Michigan, Earth and Environmental Sciences, Ann Arbor, MI, United States

Abstract:

The variability of ENSO on centennial to millennial time-scales is poorly understood due to the insufficient length, continuity, and resolution of existing paleoclimate records. Here we present a new, continuous, sub-annually resolved scanning XRF Ti record from marine sediments collected from Santa Barbara Basin (SBB) to reveal interannual precipitation changes in Southern California for the Holocene (0-9 ka). Interannual precipitation variability in Southern California is closely related to ENSO through an atmospheric teleconnection with the tropical Pacific. Wavelet analysis of the SBB Ti record demonstrates that interannual (2–7 year) precipitation variance was relatively weak prior to 4.4 ka, but significantly increased after 4.4 ka. This record demonstrates a relationship between Southern California precipitation and the tropical Pacific and extratropical climate. The inferred increase of ENSO variability during the late Holocene is generally consistent with tropical Pacific ENSO records, and may be associated with a southward shift of the ITCZ. Meanwhile, a deeper, westward-shifted Aleutian Low after 4.4 ka may have strengthened the ENSO teleconnection between the tropical Pacific and Southern California, contributing to the amplified interannual precipitation variance in the SBB record. CESM simulations through the Holocene support the role of both the ITCZ and the Aleutian Low in the enhancement of interannual precipitation variability in Southern California.