The tropical circulation change under global warming arises great attention around the world in recent decades. It has a close relationship with the tropical precipitation change and the uncertainty in its projection is one of the difficulties in climate projection.

A special review by MA Jian, a professor at the college of marine sciences in Shanghai Ocean University, Prof. HUANG Gang from Institute of Atmospheric Physics, Chinese Academy of Sciences and scientists from UK, USA and Korea published in the journal Annual Review of Earth and Planetary Sciences describes the climate change-induced responses of the tropical atmospheric circulation and their impacts on the hydrological cycle. It also depicts the theoretically predicted changes and diagnose physical mechanisms for observational and model-projected trends in large-scale and regional climate.

Multimodel ensemble and long-term mean of the sea surface temperature and precipitation in the Pacific intertropical convergence zone. The patterns show the deviations from the tropical Pacific (30°S-30°N, 120°E-80°W) mean. (Image by Ma et al., 2018)

For the large-scale circulation, the tropical circulation slows down with moisture and stratification changes, connecting to a poleward expansion of the Hadley cells and a shift of the intertropical convergence zone. Redistributions of regional precipitation consist of thermodynamic and dynamical components, including a strong offset between moisture increase and circulation weakening throughout the tropics. This allows other dynamical processes to dominate local circulation changes, such as a surface warming pattern effect over oceans and multiple mechanisms over land.To improve reliability in climate projections, the authors suggest that more fundamental understandings of pattern formation, circulation change, and the balance of various processes redistributing land rainfall are needed.

Reference：

Ma, J.*,R. Chadwick, K. Seo, C. Dong, G. Huang, G. R. Foltz and J. H. Jiang，2018: Responses of the tropical atmospheric circulation to climate change and connection to the hydrological cycle, Annual Review of Earth and Planetary Sciences, 46:549-580, https://doi.org/10.1146/annurev-earth-082517-010102

Contact: Ms. LIN Zheng, Jennylin@mail.iap.ac.cn