Our main goal is to obtain a robust understanding of the tropical Pacific SST warming pattern change, from the past to the future. This includes challenges about attribution, explanation, and projection of the pattern of surface temperature change either in response to global warming or generated internally, relevant to the CLIVAR WG. We will initiate and facilitate research activities across multiple communities, aiming at tackling the following science issues:
● Reconciling observed pattern changes since the late 20th century and future projections simulated by GCMs, and improving confidence in future projections.
● Connecting the global-mean energy budget (for understanding global-mean temperature) to the inter-hemispheric energy budget (for understanding the meridional shifts in Hadley circulation and tropical rainfall distribution). While the two perspectives are seemingly distinct, the global-mean energy budget depends on the surface warming pattern, which is then modulated by the inter-hemispheric energy transport.
● Assessing the relative time scales and magnitudes of the mechanisms of forced SST pattern change to date: i.e., ocean thermostat, weaker Walker, and Southern Ocean influence, in observations and in models, involving a ‘deep dive’ into physical mechanisms. In particular, this will involve examination of the ocean mixed-layer heat budget and thermocline processes in reanalyses and models that have been lacking in the literature.
● Attributing observed changes to forced response and internal climate variability associated with known modes such as the IPO and AMV.
● Assessing the importance of large-scale circulation changes coupled with air-sea interactions and cloud-radiative processes. In particular, investigate the role of cloud feedbacks in determining the pattern of SST change, rather than being a response to it.
● Addressing challenges in identifying and reducing model systematic errors to resolve the model-observation discrepancy.