The role of the tropical Atlantic in tropical Pacific climate variability

Interactions between Atlantic and Pacific Oceans can affect tropical Pacific variability and its global impacts at both interannual and decadal timescales, calling for a deepened understanding of the coupled Atlantic-Pacific interactions. While possible dynamical mechanisms by which the Atlantic can influence the Pacific have been identified, the effectiveness of those mechanisms has been difficult to establish using climate model simulations where Atlantic SSTs are prescribed and Pacific feedbacks cannot be realistically included. As an alternative approach, here we use a Linear Inverse Model (LIM) trained on observations and capable of correctly reproducing the observed statistics, to assess the relative role of the Atlantic-to-Pacific and Pacific-to-Atlantic influences on tropical Pacific variability. Our results indicate that Atlantic internal variability can enhance interannual SST anomalies in the eastern equatorial Pacific, and decadal SST anomalies in the central equatorial Pacific, while Pacific influences on the Atlantic tend to significantly damp tropical Pacific decadal variability. This methodological framework could also be used to assess climate models’ fidelity and reconcile existing differences among models’ results.