Intermodel differences in seasonal and regional CMIP6 divergent atmospheric heat transport

Abstract. The tropical rainband's location is closely tied to divergent atmospheric heat transport (AHT). Recent work decomposed annual and zonal-mean AHT into radiative fluxes, evaporative fluxes and sensible heat, finding that the latitudinal structure of divergent AHT strongly resembled that associated with the evaporative fluxes, and that imposed changes to evaporation in model simulations altered total divergent AHT.

Here, we generalise this decomposition to explore regional and seasonal intermodel differences in CMIP6 simulations. In historical climate, we find that the spatial structure of the total JJA and DJF AHT most resembles that linked to evaporative and radiative fluxes. Intermodel differences in divergent AHT predominantly relate to east-west rather than north-south rainband shifts. In future climate, in JJA most models show enhanced southward interhemispheric energy transport, while in DJF models instead undergo a zonal change towards more energy export from a warmer eastern Pacific.

We identify groups of models from different families that show similar decompositions of their total AHT response to climate change into the individual flux terms. This suggests that distinct storylines may exist through which warming affects the energy budget and associated tropical rainfall.