Lin Pengfei, Yu Zipeng, Lü Jianhua, Ding Mengrong, Hu Aixue, Liu Hailong
State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing 100049, China.
School of Atmospheric Sciences, Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou 510275, China.
Sci Bull (Beijing). 2019 Feb 15;64(3):198-204. doi: 10.1016/j.scib.2018.12.027. Epub 2019 Jan 6.
The Atlantic Multidedal Oscillation (AMO) is a prominent mode of sea surface temperature variability in the Atlantic and incurs significant global influence. Most coupled models failed to reproduce the observed 50-80-year AMO, but were overwhelmed by a 10-30-year AMO. Here we show that the 50-80-year AMO and 10-30-year AMO represent two different AMO regimes. The key differences are: (1) the 50-80-year AMO involves transport of warm and saline Atlantic water into the Greenland-Iceland-Norwegian (GIN) Seas prior to reaching its maximum positive phase, while such a transport is weak for the 10-30-year AMO; (2) the zonality of atmospheric variability associated with the 50-80 year AMO favors the transport of warm and saline water into the GIN Seas; (3) the disappearance of Pacific variability weakens the zonality of atmospheric variability and the transport of warm and saline water into the GIN Seas, leading to the weakening of the 50-80-year AMO. In contrast, the 10-30-year AMO does not show dependence on the variability in Pacific and in the GIN Seas and may be an Atlantic-intrinsic mode. Our results suggest that differentiating these AMO regimes and a better understanding of the cross-basin connections are essential to reconcile the current debate on the nature of AMO and hence to its reliable prediction, which is still lacking in most of coupled models.
大西洋多年代际振荡（AMO）是大西洋海表温度变化的一种显著模式，并对全球产生重大影响。大多数耦合模式未能再现观测到的50至80年周期的AMO，而是被10至30年周期的AMO主导。在此我们表明，50至80年周期的AMO和10至30年周期的AMO代表两种不同的AMO状态。关键差异在于：（1）50至80年周期的AMO在达到最大正相位之前，涉及温暖且含盐的大西洋海水向格陵兰 - 冰岛 - 挪威海（GIN海）的输送，而对于10至30年周期的AMO，这种输送较弱；（2）与50至80年周期的AMO相关的大气变化的纬向性有利于温暖且含盐的海水向GIN海的输送；（3）太平洋变化的消失削弱了大气变化的纬向性以及温暖且含盐的海水向GIN海的输送，导致50至80年周期的AMO减弱。相比之下，10至30年周期的AMO不依赖于太平洋和GIN海的变化，可能是一种大西洋内在模式。我们的结果表明，区分这些AMO状态以及更好地理解跨洋盆联系对于调和当前关于AMO本质的争论从而实现其可靠预测至关重要，而这在大多数耦合模式中仍然缺乏。
