Externally Forced and Internally Generated Decadal Climate Variability Associated with the Interdecadal Pacific Oscillation
Externally Forced and Internally Generated Decadal Climate Variability Associated with the Interdecadal Pacific Oscillation
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DOI：
10.1175/jcli-d-12-00548.1
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发表时间：
2013-09-01
影响因子：
4.9
通讯作者：
Trenberth, Kevin E.
中科院分区：
文献类型：
--
作者：
Meehl, Gerald A.;Hu, Aixue;Trenberth, Kevin E.
全球平均地表气温在某些几十年表现出快速上升（加速变暖几十年），而在其他几十年没有变暖趋势（中断几十年）。先前的一项研究表明，大气顶部约1 W m（-2）的净能量不平衡与中断期间750 m以下深海热含量的较大增加有关，而上层海洋的全球平均表面温度几乎没有升高或变暖。在这里，作者研究了与加速变暖几十年有关的过程，并讨论了温室气体增加的外部强迫和与年代际太平洋涛动（IPO）相关的内部产生的年代际气候变率的相对作用。社区气候系统模式第4版（CCSM4）的模式结果显示，加速变暖几十年的特征是全球平均地表气温快速升温，海洋上层热含量增加幅度较大，深海热含量增加幅度较小，与中断几十年相反。除了可能与南极底水（AABW）形成和大西洋经向翻转环流（AMOC）有关的过程的贡献外，首次公开活动的正相位增加了对外部强迫的响应，通常与几十年来加速变暖有关。相反，间歇期通常发生在首次公开募股的负阶段，此时外部强迫的变暖被热带太平洋内部产生的冷却所抵消。在未来的气候模拟中，出现了长达15年的内部产生的无全球变暖趋势的间歇期。这表明，目前观测到的间歇期有可能再延长几年。
Globally averaged surface air temperatures in some decades show rapid increases (accelerated warming decades), and in other decades there is no warming trend (hiatus decades). A previous study showed that the net energy imbalance at the top of the atmosphere of about 1 W m(-2) is associated with greater increases of deep ocean heat content below 750 m during the hiatus decades, while there is little globally averaged surface temperature increase or warming in the upper ocean layers. Here the authors examine processes involved with accelerated warming decades and address the relative roles of external forcing from increasing greenhouse gases and internally generated decadal climate variability associated with interdecadal Pacific oscillation (IPO). Model results from the Community Climate System Model, version 4 (CCSM4), show that accelerated warming decades are characterized by rapid warming of globally averaged surface air temperature, greater increases of heat content in the upper ocean layers, and less heat content increase in the deep ocean, opposite to the hiatus decades. In addition to contributions from processes potentially linked to Antarctic Bottom Water (AABW) formation and the Atlantic meridional overturning circulation (AMOC), the positive phase of the IPO, adding to the response to external forcing, is usually associated with accelerated warming decades. Conversely, hiatus decades typically occur with the negative phase of the IPO, when warming from the external forcing is overwhelmed by internally generated cooling in the tropical Pacific. Internally generated hiatus periods of up to 15 years with zero global warming trend are present in the future climate simulations. This suggests that there is a chance that the current observed hiatus could extend for several more years.