Participants of the ENSO RF-1

The 1^st session of the CLIVAR Research Focus (RF) on “ENSO in a Changing Climate” was held on 15 October 2017 in Busan, Rep. of Korea. This session was held one day prior to the ENSO Complexity Workshop organized by the ICCP (IBS Climate Center for Climate Physics) at Pusan National University.

The ENSO RF is a three-year effort focusing primarily on a community-wide synthesis of methods to evaluate the behavior, dynamics, and sensitivities of ENSO in coupled GCMs. To that end, the meeting focused on the following:

1. The latest results and opportunities pertaining to ENSO in a changing climate, along with ways to quantify and reduce the remaining uncertainties.  A key uncertainty identified by the panel was future changes in the zonal and meridional SST gradients of the equatorial Pacific, which strongly influence future changes in ENSO behavior and teleconnections.  A key concern is the apparent inability of most existing climate simulations to capture the magnitude of the recently observed decadal cooling of the equatorial Pacific, associated with the so-called warming hiatus.
2. Robust methods for evaluating ENSO simulations, and for interpreting model projections of the future.  The panel has produced a prototype software framework for gathering and displaying ENSO metrics, with the aim of eventual insertion into existing community model evaluation tools like the PCMDI Metrics Package and ESMValTool. The goal is to release a first version in 2018, focusing on three key areas as follows. The RF members were divided into three teams, which will meet by telecon as the metrics project moves forward.
   1. ENSO performance in historical simulations (background climatology, ENSO space/time structure and diversity, decadal modulation) ;
   2. ENSO teleconnections in historical simulations ; and
   3. ENSO dynamics and processes.
3. Response to TPOS2020 recommendations: The panel was supportive of TPOS2020’s recommendations to enhance observations over the tropical Pacific region – in particular extending several mooring lines poleward into the ITCZ and SPCZ regions.  However, some members voiced concerns about TPOS2020’s proposed removal of off-equatorial moorings along several of the meridional ribs of the Tropical Moored Array (TMA). These in-situ mooring measurements were viewed as crucial for constraining the surface heat and momentum fluxes in reanalyses, for maintaining continuity across satellite missions, and for providing long-term fixed-point records of tropical Pacific climate and ENSO.
4. ENSO summer school.  The panel is starting to plan an ENSO summer school for graduate students and early postdocs, to occur during July, 2019 in Urbino, Italy.

The venue for the ENSO RF meeting was coordinated by ICCP, to which the organizers express their sincere thanks.