大西洋经向翻转环流及其对全球气候的影响

doi:10.12006/j.issn.1673-1719.2025.001

摘要/Abstract

摘要：

全球气候在温室气体强迫作用下呈现长期变暖趋势，且伴随着与大西洋经向翻转环流（AMOC）密切相关的60~70 a的准周期多年代际振荡。AMOC是全球海洋环流的核心部分，影响全球海洋热量和淡水的分布，进而影响全球气候变化。文中回顾了有器测温度、盐度和海表面高度等观测数据以来，基于直接观测阵列和代用观测指标展示的AMOC的结构与变异过程，基于器测观测数据构建的AMOC代用指标显示，AMOC多年代际变异与全球平均表面温度的多年代际变异之间存在约45°~90°的位相差，两者之间的位相关系主要受到中深层海洋的热输送对表层气候系统能量收支平衡的影响以及气候系统外部辐射强迫作用的调制。文中还讨论了研究AMOC变异及其对全球气候变化影响过程面临的挑战：尽管观测数据显示AMOC并没有明显的趋势变化，但稀缺的观测不足以支撑数值模式模拟的AMOC减缓的现象；气候系统的外部辐射强迫作用会影响气候的内部变率，改变AMOC多年代际变异与全球表面平均温度的关系。未来需要进行持续且高质量的观测以增强对AMOC多年代际变异及其气候效应的认识，为气候模式改进和气候变化政策制定提供科学依据。

关键词: 大西洋经向翻转环流（AMOC）, 气候变化, 海洋热输送

Abstract:

In presence of anthropogenic forcing, global climate has exhibited a long-term warming trend, superimposed by a quasi-periodic multidecadal oscillation of 60—70 years, which is strongly influenced by the Atlantic Meridional Overturning Circulation (AMOC). As a critical component of the global ocean circulation, AMOC governs the distribution of ocean heat and freshwater, thereby significantly impacting climate. This paper reviews the structure and variability of AMOC based on direct observation array and the observation proxy since the instrumental temperature, salinity and sea surface height are available. We show that the AMOC leads the global mean surface temperature by approximately 45°—90°, which is primarily driven by heat transport in the intermediate and deep ocean and its effect on the surface climate system’s energy balance modulated by external radiative forcing. We also address key challenges in understanding AMOC variability and its climatic implications: first, observations did not exhibit statistically significant AMOC trend, providing few supports to the AMOC slowdown shown in numerical models; second, external radiative forcing may alter the relationship between AMOC variability and global surface temperature through its impacts on the internal climate variability. Future research should focus on continuous, high-quality observations to enhance understanding of AMOC’s multidecadal variability and its climate impacts, for more accurate climate models and more effective climate change policies.

Key words: Atlantic Meridional Overturning Circulation (AMOC), Global climate change, Ocean heat transport

陈显尧, 毕瀚文, 郝潇洁, 马天骄, 郭凌瑞. 大西洋经向翻转环流及其对全球气候的影响[J]. 气候变化研究进展, 2025, 21(4): 469-476.

CHEN Xian-Yao, BI Han-Wen, HAO Xiao-Jie, MA Tian-Jiao, GUO Ling-Rui. Variability of the Atlantic Meridional Overturning Circulation and its impact on global climate change[J]. Climate Change Research, 2025, 21(4): 469-476.

图/表 4

图1 基于1925—1927年德国大西洋探险队数据的西大西洋经向盐度断面分布图注：本图根据文献[11]重新绘制，等值线单位是盐度（psu）。

Fig. 1 Meridional cross section of salinity in the western Atlantic Ocean constructed from the measurements during the German Atlantic expeditions from 1925 to 1927

图2 (a)大洋传送带示意图[12]，(b)更为精细的“大洋传送带”示意图注：(b)图根据文献[13]重新绘制。

Fig. 2 (a) Schematic of the Great Ocean Conveyor Belt[12], (b) a more detailed schematic of the Great Ocean Conveyor Belt

图3 (a) AMOC代用指标[24-26]，(b) HadCRUT4.6数据计算的全球表面平均温度距平（GSTA）[24] 注：(b)图周围的浅色线条表示来自HadCRUT4.6的100个集合成员结果，小图是将SST回归到多年代际变率（MDV）的空间分布。

Fig. 3 AMOC and GSTA variations. (a) The AMOC fingerprint[24-26], (b) GSTA variations[24] (The inset shows the SST spatial pattern associated with MDV obtained by regressing SST onto its time series. The blue curve is the smoothed version of GSTA obtained as the sum of the secular trend and MDV. The faint lines around the solid lines are from 100 ensemble members of the HadCRUT4.6, which assess the range of uncertainty of the data used in the solid lines)

图4 观测与理论解的全球平均表面温度距平（GMST）和标准化的AMOC指数[38]及其积分时间序列(a)观测的GMST和标准化的AMOC指数，(b)观测的GMST和标准化的AMOC指数的积分， (c), (d)分别与(a),(b)一致，但为式(1)的理论解注：黑色实线为GMST，红线、蓝线为AMOC副极地上层海洋盐度指数[24]，绿线为AMOC的SST指数[25]，黑色虚线T′（MDV）是GMST多年代际振荡；阴影区域表示变暖放缓的时期，无阴影区域表示加速变暖的时期 [38]。

Fig. 4 Observed and theoretical solution of anomalous global mean surface temperature (GMST). (a) Observed GMST plotted with various normalized AMOC indices [38], (b) observed GMST plotted with the integral of various AMOC indices, normalized, (c), (d) Same as (a), (b) but for the theoretical solution of Equation (1). (The black solid line is the GMST, and the red and blue lines represent the subpolar upper-ocean salinity indices [24]. The green line denotes the SST-based AMOC fingerprint [25]. Black dash line T′ (MDV) is the multidecadal variability of GMST. The shade areas denote periods of warming slowdown and the unshaded area the period of accelerated warming [38])

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