Evaluating the “Rich-Get-Richer” Mechanism in Tropical Precipitation Change under Global Warming

作者：Chia Chou, J. David Neelin, Chao‐An Chen, Jien‐Yi Tu · 发表于：Journal of Climate · 年份：2008 · DOI：10.1175/2008jcli2471.1 · 被引用次数：770 · 研究领域：Climate variability and models、Meteorological Phenomena and Simulations、Tropical and Extratropical Cyclones Research

Abstract Examining tropical regional precipitation anomalies under global warming in 10 coupled global climate models, several mechanisms are consistently found. The tendency of rainfall to increase in convergence zones with large climatological precipitation and to decrease in subsidence regions—the rich-get-richer mechanism—has previously been examined in different approximations by Chou and Neelin, and Held and Soden. The effect of increased moisture transported by the mean circulation (the “direct moisture effect” or “thermodynamic component” in respective terminology) is relatively robust, while dynamic feedback is poorly understood and differs among models. The argument outlined states that the thermodynamic component should be a good approximation for large-scale averages; this is confirmed for averages across convection zones and descent regions, respectively. Within the convergence zones, however, dynamic feedback can substantially increase or decrease precipitation anomalies. Regions of negative precipitation anomalies within the convergence zones are associated with local weakening of ascent, and some of these exhibit horizontal dry advection associated with the “upped-ante” mechanism. Regions of increased ascent have strong positive precipitation anomalies enhanced by moisture convergence. This dynamic feedback is consistent with reduced gross moist stability due to increased moisture not being entirely compensated by effects of tropospheric warming and a vertical...