The Impact of Climate Variability and Change on the California Current System using a Pacific Pacemaker Experiment

open_access
Open Access
Author:
Kiszka, Jacqueline
Area of Honors:
Meteorology and Atmospheric Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Raymond Gabriel Najjar, Jr., Thesis Supervisor
William Henry Brune, Thesis Honors Advisor
Keywords:
Oceanography
Atmospheric Science
Climate Modeling
Climate Variability
Climate Change
ENSO
Teleconnections
California Current System
Tropical Dynamics
Abstract:
Ocean-atmosphere teleconnections driven by the El Niño-Southern Oscillation (ENSO) can have significant impacts on the physical and biogeochemical ocean properties of the California Current Large Marine Ecosystem (CCLME), one of the world’s major upwelling regions that supports important marine resources. This study aims to deepen our understanding of the impacts of ENSO on the ocean processes that influence marine ecosystems in the CCLME. This is accomplished using a Tropical Pacific Pacemaker Ensemble from the Community Earth System Model 2 (CESM2), a climate model in which 10 members have sea surface temperature (SST) anomalies in the eastern tropical Pacific that are nudged to observations from 1880 to 2020, thus capturing the observed ENSO signal. We show the statistical relationships and uncertainties between the Niño-3.4 index and multiple physical and biogeochemical ocean properties in the CCLME and compare them to a Forced Ocean-Sea Ice Simulation (FOSI) with global historical forcing. We demonstrate the expected lagged response of the CCLME to ENSO events by quantifying the correlation between the wintertime Niño-3.4 index and the following springtime CCLME anomalies, with SST having a median correlation value of 0.4 and a spread between -0.2 and 0.7, and FOSI having a mean value of 0.55. We also compare the Pacemaker to FOSI during the extreme 2015-2016 El Niño event and examine the distribution of CCLME anomalies based on ENSO strength, with 47% of strong El Niño events corresponding with springtime CCLME SST anomalies in the upper tercile of anomalies. Results from this study demonstrate the uncertainty in the ENSO–CCLME connection, with the potential to help inform resource management here.