Precipitation and atmospheric circulation are the coupled processes through which tropical ocean surface temperatures drive global weather and climate 1 – 5 . Local sea surface warming tends to increase precipitation, but this local control is difficult to disentangle from remote effects of conditions elsewhere. As an example of such a remote effect, El Niño Southern Oscillation (ENSO) events in the equatorial Pacific Ocean alter precipitation across the tropics. Atmospheric circulations associated with tropical precipitation are predominantly deep, extending up to the tropopause. Shallow atmospheric circulations 6 – 8 affecting the lower troposphere also occur, but the importance of their interaction with precipitation is unclear. Uncertainty in precipitation observations 9 , 10 and limited observations of shallow circulations 11 further obstruct our understanding of the ocean’s influence on weather and climate. Despite decades of research, persistent biases remain in many numerical model simulations 12 – 18 , including excessively wide tropical rainbands 14 , 18 , the ‘double-intertropical convergence zone problem’ 12 , 16 , 17 and too-weak responses to ENSO 15 . These biases demonstrate gaps in our understanding, reducing confidence in forecasts and projections. Here we use observations to show that seasonal tropical precipitation has a high sensitivity to local sea surface temperature. Our best observational estimate is an 80 per cent change in precipitation for every gram per kilogram change in the saturation specific humidity (itself a function of the sea surface temperature). This observed sensitivity is higher than in 43 of the 47 climate models studied, and is associated with strong shallow circulations. Models with more realistic (closer to 80%) sensitivity have smaller biases across a wide range of metrics. Our results apply to both temporal and spatial variation, over regions where climatological precipitation is about one millimetre per day or more. Our analyses of multiple independent observations, physical constraints and model data underpin these findings. The spread in model behaviour is further linked to differences in shallow convection, thus providing a focus for accelerated research to improve seasonal forecasts through multidecadal climate projections. The response of tropical precipitation to variation in sea surface temperature is stronger than in most climate models, with cool and warm ocean regions linked by strong shallow atmospheric circulations.

中文翻译：

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热带降水对当地海面温度的高度敏感性

降水和大气环流是热带海洋表面温度驱动全球天气和气候的耦合过程 1 – 5 。局部海面变暖往往会增加降水，但这种局部控制很难与其他地方条件的远程影响分开。作为这种远程效应的一个例子，赤道太平洋的厄尔尼诺南方涛动 (ENSO) 事件改变了热带地区的降水。与热带降水相关的大气环流主要是深的，一直延伸到对流层顶。浅层大气环流 6 - 8 也会影响对流层低层，但它们与降水相互作用的重要性尚不清楚。降水观测的不确定性 9 , 10 和对浅层环流的有限观察 11 进一步阻碍了我们对海洋对天气和气候影响的理解。尽管进行了数十年的研究，但在许多数值模式模拟 12-18 中仍然存在持续偏差，包括过宽的热带雨带 14、18、“双热带辐合带问题”12、16、17 以及对 ENSO 的响应太弱 15。这些偏见表明我们的理解存在差距，降低了对预测和预测的信心。在这里，我们使用观测结果表明季节性热带降水对当地海面温度具有高度敏感性。我们最好的观测估计是，饱和比湿度（它本身是海面温度的函数）每变化 1 克，降水量就会发生 80% 的变化。这种观察到的敏感性高于研究的 47 个气候模型中的 43 个，并且与强浅层环流有关。具有更现实（接近 80%）灵敏度的模型在各种指标上的偏差更小。我们的结果适用于时间和空间变化，在气候降水量约为每天一毫米或更多的地区。我们对多个独立观察、物理约束和模型数据的分析支持了这些发现。模式行为的传播与浅层对流的差异进一步相关，从而为加速研究提供了一个重点，以通过多年气候预测来改进季节性预报。热带降水对海面温度变化的响应强于大多数气候模型，