Skip to main content
Open Access Publications from the University of California

UC Berkeley

UC Berkeley Previously Published Works bannerUC Berkeley

The Interhemispheric Pattern and Long-Term Variations in the Tropical Climate over the 20th and 21st Centuries


Several lines of evidence - paleoclimate observations, model simulations, and theory - suggest that thermal forcing originating from the extratropics have a profound effect on tropical rainfall. Cold thermal forcing located in the Northern extratropics cools air and surface temperatures over the entire hemisphere, generating an interhemispheric temperature asymmetry that shifts the latitudinal position of the Intertropical Convergence Zone southwards and weaken rainfall over Northern Hemisphere summer monsoon regions. This change is associated with a northward anomalous cross-equatorial atmospheric energy transport induced by differences in the energy flux entering each hemisphere. I summarize how this 'interhemispheric pattern' could be usefully applied to understanding multidecadal and longer-timescale forced changes in tropical rainfall over the 20th and 21st centuries, focusing on three specific causes: anthropogenic aerosols, the late 1960s climate shift, and hemispheric asymmetric feedbacks to greenhouse warming.

Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View