The Pacific Ocean is a key region for coupled atmosphere-ocean phenomena that influence global climate across different timescales. Currently, seasonal-to-interannual climate predictions predominantly rely on forecasting El Niño-Southern Oscillation (ENSO) while there are emerging efforts on Pacific-rim decadal predictions based on forecasting phases of Pacific Decadal Variability (PDV). In turn global climate change projections hinge on predicting forced changes in the tropical Pacific. On this, however, there is substantial disagreement between models which favor a reduced zonal sea surface temperature gradient and observations which show an increase. The discrepancy reduces confidence in models’ future projections; the differences are critical for associated regional climate change, tropical cyclone behavior and climate sensitivity. By integrating observational analyses, theoretical demonstrations, and model experiments, this research will significantly advance our fundamental understanding of key aspects of Pacific dynamics. The gained understanding is essential for reconciling why climate models struggle to simulate historical trends in the tropical Pacific Ocean and how the models can be improved so as to provide more reliable and accurate predictions and projections of regional climate change and the rate of global warming. The lead investigator is an early career researcher and this work will advance her career focused on the ocean’s role in climate variability and ch