美国迈阿密大学He, Chengfei团队最近的研究成果提出了热带大西洋多年代际变率主要由外部作用力控制的观点。相关论文发表在2023年9月13日出版的《自然》杂志上。

热带大西洋海表温度的跨赤道梯度(主要由自1950年以来，与人为排放和火山气溶胶相关的辐射扰动驱动)是大西洋飓风形成和 Sahel 降雨的关键决定因素。在 CMIP6 地球系统模型的大集合中，这种关系是模糊的，因为这些模型高估了自1950年左右以来，北半球相对于南半球的长期变暖趋势，以及大气环流和降雨量的相关变化。当高估的趋势被去除后，海表温度与大西洋飓风形成和 Sahel 地区降雨之间的相关性作为对辐射作用力的响应而出现，特别是自1950年以来，人为气溶胶作用力一直很高。

研究表明，与整个北大西洋的海表温度相比，热带大西洋海表温度梯度对热带影响的决定作用更强，因为梯度通过局部大气环流与热带影响的物理联系更紧密。研究结果强调，大西洋飓风活动和 Sahel 地区的降雨变化可以通过人为排放和火山作用驱动的辐射作用力进行预测，但更可靠的预测受到信号—噪声悖论和未来气候作用力的不确定性的限制。

据介绍，热带大西洋气候的特征是大西洋海表温度(SSTs)、 Sahel 降雨和飓风活动与多年代际变率显著和相关。由于模型和观测的不确定性，这些系统之间物理关系的起源仍然存在争议。

附：英文原文

Title: Tropical Atlantic multidecadal variability is dominated by external forcing

Author: He, Chengfei, Clement, Amy C., Kramer, Sydney M., Cane, Mark A., Klavans, Jeremy M., Fenske, Tyler M., Murphy, Lisa N.

Issue&Volume: 2023-09-13

Abstract: The tropical Atlantic climate is characterized by prominent and correlated multidecadal variability in Atlantic sea surface temperatures (SSTs), Sahel rainfall and hurricane activity. Owing to uncertainties in both the models and the observations, the origin of the physical relationships among these systems has remained controversial. Here we show that the cross-equatorial gradient in tropical Atlantic SSTs—largely driven by radiative perturbations associated with anthropogenic emissions and volcanic aerosols since 1950—is a key determinant of Atlantic hurricane formation and Sahel rainfall. The relationship is obscured in a large ensemble of CMIP Earth system models, because the models overestimate long-term trends for warming in the Northern Hemisphere relative to the Southern Hemisphere from around 1950 as well as associated changes in atmospheric circulation and rainfall. When the overestimated trends are removed, correlations between SSTs and Atlantic hurricane formation and Sahel rainfall emerge as a response to radiative forcing, especially since 1950 when anthropogenic aerosol forcing has been high. Our findings establish that the tropical Atlantic SST gradient is a stronger determinant of tropical impacts than SSTs across the entire North Atlantic, because the gradient is more physically connected to tropical impacts via local atmospheric circulations. Our findings highlight that Atlantic hurricane activity and Sahel rainfall variations can be predicted from radiative forcing driven by anthropogenic emissions and volcanism, but firmer predictions are limited by the signal-to-noise paradox and uncertainty in future climate forcings. Anthropogenic and volcanic aerosols dominate multidecadal variability in aspects of the tropical Atlantic climate, such as sea surface temperatures, Sahel rainfall and hurricanes.

DOI: 10.1038/s41586-023-06489-4

Source: https://www.nature.com/articles/s41586-023-06489-4