Background

During 2020-2025, the CLIVAR Research Focus on Tropical Basin Interaction (TBI RF) has helped advance understanding of interactions among the tropical Pacific, Atlantic, and Indian Oceans. Through a series of coordinated activities, the RF brought together researchers working on observations, theory, and modeling, and facilitated progress on the mechanisms and pathways through which variability is communicated across basins.

One important outcome of the TBI RF has been the development of community tools, frameworks, and coordinated activities that now support a wide range of interbasin studies. These include the Tropical Basin Interaction Model Intercomparison Project (TBIMIP), conceptual and statistical tools such as the interbasin Linear Inverse Model (LIM), and more recently, theoretical frameworks such as the extended recharge oscillator (XRO), and the creation of a paleoclimate section in the Climate Data Guide at NSF NCAR. Together, these efforts have established a foundation for both process-oriented studies and model-based analyses of interbasin interactions.

At the same time, the TBI RF was established as a time-limited activity. While many initiatives were successfully launched during its lifetime, several core efforts are still at a stage where continued coordination is essential. As the RF comes to an end, there is a clear need to carry forward selected activities to ensure that the scientific outcomes envisioned at the start of the RF can be fully realized.

Motivation and Objectives

The motivation for establishing a Working Group on Tropical Basin Interaction under the CLIVAR Climate Dynamics Panel (CDP) is to provide continuity for key activities initiated within the TBI RF and to support their further development. 

A primary example is TBIMIP. With coordinated simulations now being completed by multiple modeling centers, continued oversight is needed to facilitate joint analysis, guide the design of additional or follow- up experiments, and support the publication and dissemination of the model output, including data sharing through the Earth System Grid Federation (ESGF).

In addition, several conceptual and reduced-complexity tools developed within the TBI community, such as the interbasin LIM, would benefit from further development and clearer documentation. These approaches play an important role in linking theory, observations, and comprehensive climate models, and in improving physical understanding of interbasin processes.

The TBI Webinar series initiated during the RF has also proven to be a useful mechanism for maintaining regular scientific exchange within the community, with participation across regions and career stages. Continuing this activity would help sustain momentum and visibility of TBI-related research within CLIVAR.

Finally, the maturation of coordinated experiments, theoretical frameworks, and observational insights creates an opportunity to explore the development of a comprehensive TBI review paper. Such a synthesis would consolidate recent progress, identify remaining challenges, and provide guidance for future research directions.

Taken together, these considerations motivate the formation of a dedicated Working Group to support ongoing activities, consolidate outcomes from the TBI RF, and advance research on tropical basin interactions. The CLIVAR CDP would be the ideal host for this Working Group because it is thematically well aligned with the goals of TBI research. Notably, its terms of reference include “Ocean basin to ocean basin and tropical-extratropical teleconnections”. Thus, the proposed Working Group would be well positioned to contribute to the goals of the CDP. 

In addition, the proposed TBI Working Group will actively coordinate with other CLIVAR working groups and regional panels on related topics. In particular, it will seek to strengthen connections with relevant groups such as TROPICS, PATAC, OMDP, and other working groups under the regional panels. Such interactions may include joint webinars, co-organized conference sessions, and participation in each other’s meetings, thereby enhancing exchange and collaboration across the CLIVAR community.

Terms of reference

1. Facilitate continued development and coordination of the TBIMIP, including oversight of ongoing coordinated experiments, guidance on potential follow-up or complementary experiments, and coordination of data documentation and submission of model output to the ESGF.
2. Support coordinated analysis of TBIMIP and related model simulations by defining core diagnostics and evaluation metrics for tropical basin interactions, enabling inter-model comparison and
   identification of key model biases, organizing joint analysis among participating modeling centers, and promoting publication of multi-model results in peer-reviewed journals.
3. Promote research on tropical basin interactions to advance understanding of physical mechanisms and predictability, and to identify remaining key scientific problems, through targeted analyses
   combining model simulations, observations, and reanalysis products.
4. Maintain community engagement activities related to tropical basin interaction research, and strengthen coordination with other CLIVAR panels and working groups addressing related aspects of tropical climate variability and teleconnections, through regular webinars, in person or hybrid workshops, focused sessions at international conferences, and other shared community activities.
5. Promote synthesis of recent progress in understanding tropical basin interactions, including coordination of at least one community review paper and/or other synthesis products that summarize key advances, remaining challenges, and priorities for future research.
6. Communicate outcomes, progress, and emerging scientific needs to the CLIVAR CDP, and coordinate with other relevant CLIVAR panels and working groups as appropriate, including through regular Working Group meetings to review activities and align next steps.

Membership