当前位置: X-MOL 学术Clim. Dyn. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Reconstructing atmospheric circulation and sea-ice extent in the West Antarctic over the past 200 years using data assimilation
Climate Dynamics ( IF 3.8 ) Pub Date : 2021-07-13 , DOI: 10.1007/s00382-021-05879-6
Quentin Dalaiden 1 , Hugues Goosse 1 , Jeanne Rezsöhazy 1, 2 , Elizabeth R. Thomas 3
Affiliation  

The West Antarctic climate has witnessed large changes during the second half of the twentieth century including a strong and widespread continental warming, important regional changes in sea-ice extent and snow accumulation, as well as a major mass loss from the melting of some ice shelves. However, the potential links between those observed changes are still unclear and instrumental data do not allow determination of whether they are part of a long-term evolution or specific to the recent decades. In this study, we analyze the climate variability of the past two centuries in the West Antarctic sector by reconstructing the key atmospheric variables (atmospheric circulation, near-surface air temperature and snow accumulation) as well as the sea-ice extent at the annual timescale using a data assimilation approach. To this end, information from Antarctic ice core records (snow accumulation and \(\delta ^{{18}}\hbox{O}\)) and tree-ring width records situated in the mid-latitudes of the Southern Hemisphere are combined with the physics of climate models using a data assimilation method. This ultimately provides a complete spatial reconstruction over the West Antarctic region. Our reconstruction reproduces well the main characteristics of the observed changes over the instrumental period. We show that the observed sea-ice reduction in the Bellingshausen-Amundsen Sea sector over the satellite era is part of a long-term trend, starting at around 1850 CE, while the sea-ice expansion in the Ross Sea sector has only started around 1950 CE. Furthermore, according to our reconstruction, the Amundsen Sea Low pressure (ASL) displays no significant linear trend in its strength or position over 1850–1950 CE but becomes stronger and shifts eastward afterwards. The year-to-year sea-ice variations in the Ross Sea sector are strongly related to the ASL variability over the past two centuries, including the recent trends. By contrast, the link between ASL and sea-ice in the Bellingshausen-Amundsen Sea sector changes with time, being stronger in recent decades than before. Our reconstruction also suggests that the continental response to the variability of the ASL may not be stationary over time, being significantly affected by modification of the mean atmospheric circulation. Finally, we show that the widespread warming since 1958 CE in West Antarctica is unusual in the context of past 200 years and is explained by both the deeper ASL and the positive phase of the Southern Annular Mode.



中文翻译:

利用资料同化重建过去 200 年来南极西部的大气环流和海冰范围

20 世纪下半叶,南极西部气候发生了巨大变化,包括强烈而广泛的大陆变暖,海冰范围和积雪的重要区域变化,以及一些冰架融化造成的重大质量损失。 . 然而,这些观察到的变化之间的潜在联系仍不清楚,仪器数据无法确定它们是长期演变的一部分还是最近几十年特有的。在这项研究中,我们通过重建关键大气变量(大气环流、近地表气温和积雪)以及每年时间尺度的海冰范围,分析了南极西部地区过去两个世纪的气候变化。使用数据同化方法。为此,\(\delta ^{{18}}\hbox{O}\)) 和位于南半球中纬度的树木年轮宽度记录使用数据同化方法与气候模型的物理学相结合。这最终提供了对南极西部地区的完整空间重建。我们的重建很好地再现了仪器时期观察到的变化的主要特征。我们表明,在卫星时代观察到的贝林斯豪森-阿蒙森海区海冰减少是长期趋势的一部分,从公元 1850 年左右开始,而罗斯海区的海冰扩张仅在公元 1950 年。此外,根据我们的重建,阿蒙森海低压(ASL)在公元 1850 年至 1950 年期间的强度或位置没有显示出显着的线性趋势,但之后变得更强并向东移动。罗斯海地区的逐年海冰变化与过去两个世纪的 ASL 变化密切相关,包括最近的趋势。相比之下,ASL 与贝灵斯豪森-阿蒙森海区海冰之间的联系随着时间的推移而变化,近几十年来比以前更加紧密。我们的重建还表明,大陆对 ASL 变化的响应可能不会随着时间的推移而稳定,受到平均大气环流修正的显着影响。最后,我们表明自 1958 年 CE 以来西南极洲的普遍变暖在过去 200 年的背景下是不寻常的,并且可以通过更深的 ASL 和南部环形模式的正相位来解释。包括最近的趋势。相比之下,ASL 与贝灵斯豪森-阿蒙森海区海冰之间的联系随着时间的推移而变化,近几十年来比以前更加紧密。我们的重建还表明,大陆对 ASL 变化的响应可能不会随着时间的推移而稳定,受到平均大气环流修正的显着影响。最后,我们表明自 1958 年 CE 以来西南极洲的普遍变暖在过去 200 年的背景下是不寻常的,并且可以通过更深的 ASL 和南部环形模式的正相位来解释。包括最近的趋势。相比之下,ASL 与贝灵斯豪森-阿蒙森海区海冰之间的联系随着时间的推移而变化,近几十年来比以前更加紧密。我们的重建还表明,大陆对 ASL 变化的响应可能不会随着时间的推移而稳定,受到平均大气环流修正的显着影响。最后,我们表明自 1958 年 CE 以来西南极洲的普遍变暖在过去 200 年的背景下是不寻常的,并且可以通过更深的 ASL 和南部环形模式的正相位来解释。我们的重建还表明,大陆对 ASL 变化的响应可能不会随着时间的推移而稳定,受到平均大气环流修正的显着影响。最后,我们表明自 1958 年 CE 以来西南极洲的普遍变暖在过去 200 年的背景下是不寻常的,并且可以通过更深的 ASL 和南部环形模式的正相位来解释。我们的重建还表明,大陆对 ASL 变化的响应可能不会随着时间的推移而稳定,受到平均大气环流修正的显着影响。最后,我们表明自 1958 年 CE 以来西南极洲的普遍变暖在过去 200 年的背景下是不寻常的,并且可以通过更深的 ASL 和南部环形模式的正相位来解释。

更新日期:2021-07-13
down
wechat
bug