Australia: The Land Where Time Began

A biography of the Australian continent 

Global Warming - Patterns of Seasonal Response of Tropical Rainfall

In regional climate change and variability around the Earth tropical convection is an important factor(Alexander et al., 2002; Shin & , Sardeshmukh, 2011), the response to global warming of regional precipitation being spatially variable, and projections by state-of-the-art models have large uncertainties in regard to the geographic distribution of changes in precipitation (Meehl et al., 2007; Zhang et al., 2007; Ma &Xie, 2013). According to the authors1 there are 2 views regarding changes in tropical rainfall: one is the wet-get-wetter (Neelin, Chou & Su, 2003), according to which rainfall will increase in regions that are presently rainy, the other is warmer-get-wetter, predicting that rainfall will increase where sea surfaces temperature rise is greater than the mean surface warming in the tropics. In this study the authors1 analysed simulations with 18 models from the Coupled Model Intercomparison Project (CMIP5) and present a unified view of seasonal changes. Their findings indicate that at the Equator ascending atmospheric flow is induced by the pattern of ocean warming with subsidence on the flanks, which anchors a band of increased annual mean rainfall near the Equator which reflects the warmer-get-wetter view. This climatological ascending motion moves back and forth across the Equator following the location of the Sun, which pumps water upwards from the boundary layer which causes the seasonal rainfall anomalies to reflect the wet-get-wetter pattern. The sum of the annual mean and seasonal anomalies is the seasonal mean rainfall, which therefore combines that trends of both the warm-get-wetter and the wet-get-wetter patterns. Though the patter of ocean surface warming is poorly constrained (Tokinaga, Xie, Deser, Kosaka & Okumura, 2012; Vecchi & Soden, 2007) and given that the precipitation climatology is well preserved, the results obtained by the authors1 suggests that projections of tropical seasonal mean rainfall are more reliable than the annual mean.


Sources & Further reading

  1. Huang, Ping, Shang-Ping Xie, Kaiming Hu, Gang Huang, and Ronghui Huang. "Patterns of the Seasonal Response of Tropical Rainfall to Global Warming." Nature Geosci 6, no. 5 (05//print 2013): 357-61.


Author: M. H. Monroe
Last updated 17/05/2013
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