The overturning circulation of the ocean, which carries heat from the Southern to the Northern Hemisphere, contributes significantly to the peak in tropical rainfall just north of the equator, reports a paper published online this week in Nature Geoscience. The findings suggest that a reduction in the strength of the overturning circulation with warming, as has been previously suggested, could alter precipitation patterns in the tropics.

Dargan Frierson and colleagues assessed the effect of oceanic heat transport on the distribution of tropical rainfall, using satellite observations, reanalysis data and model simulations. They find that the northward transport of heat by the ocean overturning circulation pushes the tropical rain band just north of the equator.

In an accompanying News and Views article, John Fasullo says “the findings provide insights into the processes governing the distribution of rainfall in the tropics.”