资源环境科技发展态势分析平台

The Hadley cell (HC) plays an important role in setting the strength and position of the hydrological cycle. Climate projections show a weakening of the HC, together with widening of its vertical and meridional extents. These changes are projected to have profound global climatic impacts. Current theories for the HC response to increased greenhouse gases account only for atmospheric and oceanic thermodynamic changes and not for oceanic circulation changes. Here the effects of ocean circulation changes on the HC response to increased greenhouse gases are examined by comparing fully coupled and slab ocean model configurations. By reducing the warming of both the sea surface and the atmosphere, changes in ocean circulation reduce the HC response to increased CO2 concentrations. This reduced warming suppresses convective heating, which reduces the weakening of the HC and the stabilization at low latitudes, and thus also reduces the meridional (in the Southern Hemisphere) and vertical HC expansion.

Plain Language Summary Given the importance of tropical circulation in affecting low-latitude climate, it is crucial to understand the projected response of tropical circulation to anthropogenic emissions. To fully understand the tropical circulation response, one must account for the internal feedbacks between the different components of the climate system. Here we study the effect of changes in ocean circulation in response to increased greenhouse gases on the tropical circulation. We find that ocean circulation acts to reduce the projected response of tropical circulation to anthropogenic emissions. This emphasizes the importance in using models with ocean circulation, when studying the long-term atmospheric response to increased greenhouse gases.