Changes in the strength and width of the Hadley Circulation since 1871
Changes in the strength and width of the Hadley Circulation since 1871
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DOI：
10.5194/cp-8-1169-2012
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发表时间：
2012-07
影响因子：
4.3
通讯作者：
Jinghai Liu;M. Song;Yongyun Hu;Xiaobo Ren
中科院分区：
文献类型：
--
作者：
Jinghai Liu;M. Song;Yongyun Hu;Xiaobo Ren
最近的研究表明，哈德利环流在过去30年里不断增强和扩大，这对亚热带社会具有重要的影响，并可能导致全球气候的深刻变化。然而，在解释哈德利环流的长期变化时应该考虑的这种强化和扩张的稳健性仍然是一个有争议的问题。哈德利环流在较长时期内是如何演变的，这在很大程度上仍然是未知的。在这里，我们用20世纪的再分析呈现了哈德利环流的长期变化。它显示了自20世纪70年代末以来哈德利环流的轻微加强和扩大，这与最近的评估不一致。然而，在百年尺度上（1871-2008），哈德利环流呈现出更强烈和更窄的趋势。更重要的是，自1871年以来，哈德利环流的宽度可能还没有完成一个生命周期。19世纪末至20世纪初哈德利环流的强度和宽度显示出强烈的自然变率，超过了近几十年来与全球变暖同时发生的变率。这些发现提出了一个问题：最近哈德利环流的变化主要是由于温室效应变暖，还是由于哈德利环流的长周期振荡——比以前的研究中观察到的要长得多。
Recent studies demonstrate that the Hadley Circu- lation has intensified and expanded for the past three decades, which has important implications for subtropical societies and may lead to profound changes in global climate. How- ever, the robustness of this intensification and expansion that should be considered when interpreting long-term changes of the Hadley Circulation is still a matter of debate. It also remains largely unknown how the Hadley Circulation has evolved over longer periods. Here, we present long-term vari- ability of the Hadley Circulation using the 20th Century Re- analysis. It shows a slight strengthening and widening of the Hadley Circulation since the late 1970s, which is not in- consistent with recent assessments. However, over centennial timescales (1871-2008), the Hadley Circulation shows a ten- dency towards a more intense and narrower state. More im- portantly, the width of the Hadley Circulation might have not yet completed a life-cycle since 1871. The strength and width of the Hadley Circulation during the late 19th to early 20th century show strong natural variability, exceeding variability that coincides with global warming in recent decades. These findings raise the question of whether the recent change in the Hadley Circulation is primarily attributed to greenhouse warming or to a long-period oscillation of the Hadley Circu- lation - substantially longer than that observed in previous studies.