Title: Detecting cross-equatorial wind change as a fingerprint of climate response to anthropogenic aerosol forcing

Journal: Geophysical Research Letters, 43: 3444-3450

Authors: WANG H., S. -P. Xie*, H. Tokinaga, Q. -Y. Liu, and Y. Kosaka

Abstract:Anthropogenic aerosols are a major driver of the 20th century climate change. In climate models, the aerosol forcing, larger in the Northern than Southern Hemisphere, induces an inter-hemispheric Hadley circulation. In support of the model result, we detected a robust change in the zonal-mean cross-equatorial wind over the past 60 years from ship observations and reanalyses, accompanied by physically consistent changes in atmospheric pressure and marine cloud cover. Single forcing experiments indicate that the observed change in cross-equatorial wind is a fingerprint of aerosol forcing. This zonal-mean mode follows the evolution of global aerosol forcing that is distinct from regional changes in the Atlantic sector. Atmospheric simulations successfully reproduce this inter-hemispheric mode, indicating the importance of sea surface temperature mediation in response to anthropogenic aerosol forcing. As societies awaken to reduce aerosol emissions, a phase reversal of this inter-hemispheric mode is expected in the 21st century.