Investigating Tropical Basin Interactions: Insights from the TBIMIP Pacemaker Experiments

Large-scale interactions among the three tropical ocean basins—the Pacific, Atlantic, and Indian Oceans—can influence or modify climate variability. The international CLIVAR initiative on Tropical Basin Interactions (TBI) seeks to establish a unified understanding of the mechanisms driving these interactions and their role in climate predictability. This paper introduces the Tropical Basin Interaction Model Intercomparison Project (TBIMIP), which provides an experimental framework for investigating interactions among the tropical basins. Within the TBIMIP, a series of three-ocean "pacemaker" experiments were conducted using the CESM2 model, in line with the experimental protocol. Specifically, Tier 2 experiments, where sea surface temperatures (SSTs) were restored to observed full-field data, were carried out by the South China Sea Institute of Oceanology, Chinese Academy of Sciences. These experiments, by restoring both observed anomalies and climatological means, allow for the examination of how biases in the mean-state of one ocean might influence the mean state of others. Furthermore, they enable an exploration of how correcting these mean-state biases could affect the large-scale interactions between the three tropical ocean basins.