Regime-Oriented Causal Model Evaluation of Atlantic–Pacific Teleconnections in CMIP6
Key metrics of climate change are strongly associated with Pacific Decadal Variability (PDV) and Atlantic Multidecadal Variability (AMV). Recent advances in simulating patterns of such modes point to exploring and applying new approaches in the model evaluation framework. As they alternate between warm and cold phases, the interplay between PDV and AMV varies over decadal to multidecadal timescales.
We investigate the changing (phase-dependent) causal fingerprint in the Atlantic-Pacific interactions by comparing the causal networks from model simulations to those from reanalysis data. This regime-oriented causal model evaluation assesses the ability of models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6) to represent the observed changing interactions between PDV, AMV, and their extra-tropical teleconnections.
We show that the causal graphs obtained from reanalysis and CMIP6 model time-series information can identify regime-dependent causal structures, thereby quantifying pathways of Atlantic-Pacific teleconnections in new ways. The causal networks show that there is better network similarity when PDV and AMV are out of phase compared to other regimes.