The impact of air–sea interactions on the representation of tropical precipitation extremes

The impacts of air–sea interactions on the representation of tropical precipitation extremes are investigated using an atmosphere–ocean-mixed-layer coupled model. The coupled model is compared to two atmosphere-only simulations driven by the coupled model sea-surface temperatures (SSTs): one with 31-day running means (31d), the other with a repeating mean annual cycle. This allows separation of the effects of inter-annual SST variability from those of coupled feedbacks on shorter timescales. Crucially, all simulations have a consistent mean state with very small SST biases against present-day climatology. 31d overestimates the frequency, intensity and persistence of extreme tropical precipitation relative to the coupled model, likely due to excessive SST-forced precipitation variability. This implies that atmosphere-only attribution and time-slice experiments may overestimate the strength and duration of precipitation extremes. In the coupled model, air–sea feedbacks damp extreme precipitation, through negative local thermodynamic feedbacks between convection, surface fluxes and SST