The Pacific Warm Pool Mixed Layer Heat Budget: Model versus Observations

To advance understanding of the western Pacific warm pool, we compare the oceanic mixed layer (ML) heat budget for this region in GFDL’s new FLOR global coupled model against observations and ocean reanalyses. Beginning with the model’s full tendency equation diagnosed hourly, we systematically approximate the ML heat budget to facilitate comparison with the monthly-mean fields that are more commonly diagnosed in simulations and reanalyses. Results are presented comparing sub-daily, daily-mean, and monthly-mean aspects of the simulated budget to ocean reanalyses and high-frequency observations from moored buoys. In particular, we describe the heat budget of the ocean ML volume spanning the western equatorial Pacific within 150°E-180°E, 10°S-10°N, as a function of season, with advective fluxes decomposed into the components passing through each of the six faces of the domain. Local ML budgets are also evaluated and contrasted at 180°E versus 150°E, where differences in thermal stratification strongly affect the relative roles of advection, entrainment, and vertical diffusion. The results provide a basis for understanding model biases in this region, and implications for model development, observing system design, reanalyses and forecasts, and future climate change will be discussed.