The 2023 CLIVAR workshop on the tropical Pacific and its interbasin interactions was successfully organized and held from 14 to 17 February 2023 at Monash University, Melbourne, Australia and with virtual access. The workshop was jointly organized by CLIVAR Pacific Region Panel, Tropical Pacific Decadal Variability (TPDV) Working Group, ENSO conceptual model Working Group and the CLIVAR Tropical Basin Interaction research focus. It was an intellectually stimulating meeting, which also provided excellent opportunities to spend time with colleagues and make new connections. It was especially refreshing to have that stimulating get-together after three years of pandemics. Chief amongst the goals for this workshop was to provide opportunities to connect within and across the three research groups represented at this meeting, share the latest research with each other, and identify synergies for current and future collaborations. Over 130 participants from 26 countries attended the workshop, including 45 in-person and 87 online.

In order to provide more opportunities for early career researchers and scientists from developing nations to listen to the talks of cutting-edge research, the plenary sessions on Feb. 14 were open to the public, and received 60 additional participants for this particular day. The four plenary sessions featured an anchor talk for each of the participating groups (TBI RF, TPDV WG and ENSO Conceptual Model WG) to provide an introduction to the group’s aims and progress, which was followed by four talks related to each of the themes. The last session of this day consisted of talks under the common theme of “ENSO and the impacts of climate change”.

The workshop program from Wednesday to Friday was designed to allow for sufficient time for each of the individual groups to carry out their agenda, while also providing a venue and time to explore overlaps. To this end, each of these three days had a focus on one particular group [i.e., Wednesday had a TPDV focus, Thursday had a TBI focus while Friday had an ENSO conceptual model working group focus]. In practice, the focus group for each day had full attendance of all members (including online participants) for the first three sessions of the day. Attending participants who were not in the particular days focus working group spent the time in parallel sessions with their respective non-focus groups. The last session of the day included three pre-selected talks that fit the theme of the session, followed by open discussions to further explore potential overlaps and pathways forward, including new research directions. Discussions highlighted the need to better understand the implications of tropical basin interactions for both ENSO and TPDV, in particular regarding the identification of the dominant interactions, and their magnitudes. For instance, the relevance of Recharge Oscillator-type simple models to investigate basin interactions was discussed between the TBI and ENSO conceptual model WG.

A major task for the TPDV WG and ENSO Conceptual Model WG was to finalize the text and figures of the review papers that they are preparing for submission in 2023, as main outcomes of the WGs activities. Meanwhile, the TBI RF discussed the protocols for coordinated model experiments and other activities, including the summer school (https://indico.ictp.it/event/10198) that will be held jointly with the CLIVAR Climate Dynamics Panel this year. The session on the experiment design consisted of several presentations with preliminary results from various test runs, followed by a discussion on two crucial aspects of the experiment design: the SST restoring time scale and the latitudinal width of the restoring region. The discussions were instrumental in taking the experiment design one step closer to finalization.

Preceding the workshop, the 15^th Session of CLIVAR Pacific Region Panel (PRP-15) was organized on 13 February 2023, which was the first face-to-face meeting for the panel after 3-year online sessions due to COVID. The TBI RF also met during the workshop on Feb. 16, as the first in-person meeting since its establishment in 2020.