Patterns of the seasonal response of tropical rainfall to global warming
Patterns of the seasonal response of tropical rainfall to global warming
复制标题
热带降雨对全球变暖的季节性响应模式
DOI：
10.1038/ngeo1792
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发表时间：
2013-05-01
影响因子：
18.3
通讯作者：
Huang, Ronghui
中科院分区：
文献类型：
--
作者：
Huang, Ping;Xie, Shang-Ping;Huang, Ronghui
热带对流是全球区域气候变率和变化的重要因素。区域降水对全球变暖的响应在空间上是可变的，最先进的模型预测在降水变化的地理分布方面存在很大的不确定性。关于热带降雨变化存在两种观点：一种预测当前多雨地区降雨量增加（湿变湿），，另一种则认为当海面温度上升超过热带地区平均表面变暖时降雨量增加（暖变湿），,,。在这里，我们分析了耦合模型比较项目 (CMIP5) 的 18 个模型的模拟结果，并提出了季节性降雨变化的统一观点。我们发现，海洋变暖的模式导致赤道处的大气流量上升和侧翼的下沉，从而固定了赤道附近的年平均降雨量增加带，这反映了温暖变得更湿润的观点。然而，这种气候上升运动随着太阳在赤道上来回移动，从边界层向上抽吸水分，导致季节性降雨异常遵循湿变湿的模式。季节平均降雨量是年平均降雨量和季节异常降雨量的总和，因此结合了湿变湿和变暖变湿的趋势。鉴于降水气候学得到了很好的观察，而海洋表面变暖的模式却很少受到限制，我们的结果表明，热带季节平均降雨量的预测比年平均降雨量更可靠。
Tropical convection is an important factor in regional climate variability and change around the globe,. The response of regional precipitation to global warming is spatially variable, and state-of-the-art model projections suffer large uncertainties in the geographic distribution of precipitation changes,,. Two views exist regarding tropical rainfall change: one predicts increased rainfall in presently rainy regions (wet-get-wetter),,, and the other suggests increased rainfall where the rise in sea surface temperature exceeds the mean surface warming in the tropics (warmer-get-wetter),,,. Here we analyse simulations with 18 models from the Coupled Model Intercomparison Project (CMIP5), and present a unifying view for seasonal rainfall change. We find that the pattern of ocean warming induces ascending atmospheric flow at the Equator and subsidence on the flanks, anchoring a band of annual mean rainfall increase near the Equator that reflects the warmer-get-wetter view. However, this climatological ascending motion marches back and forth across the Equator with the Sun, pumping moisture upwards from the boundary layer and causing seasonal rainfall anomalies to follow a wet-get-wetter pattern. The seasonal mean rainfall, which is the sum of the annual mean and seasonal anomalies, thus combines the wet-get-wetter and warmer-get-wetter trends. Given that precipitation climatology is well observed whereas the pattern of ocean surface warming is poorly constrained,, our results suggest that projections of tropical seasonal mean rainfall are more reliable than the annual mean.