Authors:Ping Huang & Shang-Ping Xie
Abstract:
El Niño/Southern Oscillation (ENSO) is a mode of natural variability that has considerable impacts on global climate and ecosystems1, 2, 3, 4, through rainfall variability in the tropical Pacific and atmospheric teleconnections5. In response to global warming, ENSO-driven rainfall variability is projected to intensify over the central-eastern Pacific but weaken over the western Pacific, whereas ENSO-related sea surface temperature variability is projected to decrease6, 7, 8, 9, 10, 11, 12, 13, 14. Here, we explore the mechanisms that lead to changes in ENSO-driven rainfall variability in the tropical Pacific in response to global warming, with the help of a moisture budget decomposition for simulations from eighteen state-of-the-art climate models15. We identify two opposing mechanisms that approximately offset each other: the increase in mean-state moisture content associated with surface warming strengthens ENSO-related rainfall anomalies7, whereas the projected reduction in ENSO-related variability of sea surface temperatures suppresses rainfall. Two additional effects—spatially non-uniform changes in background sea surface temperatures and structural changes in sea surface temperature related to ENSO—both enhance central-eastern Pacific rainfall variability while dampening variability in the western Pacific, in nearly equal amounts. Our decomposition method may be generalized to investigate how rainfall variability would change owing to nonlinear interactions between background sea surface temperatures and their variability.
Link:http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2571.html
