Tightening of tropical ascent and high clouds key to precipitation change in a warmer climate

Hui Su; Jonathan H Jiang; J David Neelin; T Janice Shen; Chengxing Zhai; Qing Yue; Zhien Wang; Lei Huang; Yong-Sang Choi; Graeme L Stephens; Yuk L Yung

doi:10.1038/ncomms15771

Tightening of tropical ascent and high clouds key to precipitation change in a warmer climate

Nat Commun. 2017 Jun 7:8:15771. doi: 10.1038/ncomms15771.

Authors

Hui Su¹, Jonathan H Jiang¹, J David Neelin², T Janice Shen¹, Chengxing Zhai¹, Qing Yue¹, Zhien Wang³, Lei Huang^{1

4}, Yong-Sang Choi⁵, Graeme L Stephens¹, Yuk L Yung⁶

Affiliations

¹ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 183-701, Pasadena, California 91109-8099, USA.
² Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Los Angeles, California 90095, USA.
³ Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming 82071, USA.
⁴ Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, USA.
⁵ Department of Environmental Science and Engineering, Ewha Womans University, Seoul 120-750, South Korea.
⁶ Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA.

Abstract

The change of global-mean precipitation under global warming and interannual variability is predominantly controlled by the change of atmospheric longwave radiative cooling. Here we show that tightening of the ascending branch of the Hadley Circulation coupled with a decrease in tropical high cloud fraction is key in modulating precipitation response to surface warming. The magnitude of high cloud shrinkage is a primary contributor to the intermodel spread in the changes of tropical-mean outgoing longwave radiation (OLR) and global-mean precipitation per unit surface warming (dP/dT_s) for both interannual variability and global warming. Compared to observations, most Coupled Model Inter-comparison Project Phase 5 models underestimate the rates of interannual tropical-mean dOLR/dT_s and global-mean dP/dT_s, consistent with the muted tropical high cloud shrinkage. We find that the five models that agree with the observation-based interannual dP/dT_s all predict dP/dT_s under global warming higher than the ensemble mean dP/dT_s from the ∼20 models analysed in this study.

Publication types

Research Support, Non-U.S. Gov't