Christine Chung: Investigating the Impacts of Tropical Atlantic Variability on the Pacific Warming Trend
Authors: Christine Chung, Zoe Gillett, Ghyslaine Boschat
Introduction and scientific context:
Observed tropical Pacific sea surface temperature (SST) trends over recent decades differ substantially from the El Niño-like warming simulated by many climate models. Inter-basin interactions have been proposed as a key mechanism influencing Pacific climate variability and trends, with tropical Atlantic variability potentially modulating Pacific SSTs through atmospheric teleconnections. Understanding these interactions is important for improving confidence in simulated and projected climate change.
Methodology/project summary:
To investigate the role of tropical Atlantic variability in shaping Pacific warming patterns, we conducted a suite of pacemaker-style experiments using ACCESS-CM2. In one set of experiments, tropical Atlantic variability was suppressed while the externally forced warming trend from ACCESS-CM2 CMIP6 Historical simulations was imposed. These simulations are compared with the CMIP6 Historical runs, as well as experiments in which tropical Atlantic variability was similarly suppressed under piControl conditions, without an imposed warming trend. The experimental design enables isolation of the influence of tropical Atlantic variability on the Pacific response to external forcing.
Results:
Initial results indicate that suppressing tropical Atlantic variability enhances the El Niño-like warming trend in the tropical Pacific. Results also indicate that, when tropical Atlantic variability is suppressed, decadal variability in the Pacific is increased, while interannual variability weakens.
Audience:
Climate modellers, climate scientists with an interest in tropical variability and climate change
Keywords: Tropical Atlantic variability; Pacific warming trend; El Niño-like warming; pacemaker experiments; ACCESS-CM2.