Reconstructing wind strength and atmospheric circulation in West Antarctica over the past 300 years

重建过去300年来南极洲西部的风力和大气环流

• 批准号: NE/J020710/1
• 负责人: Elizabeth Thomas
• 金额: $ 36.62万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ020710%2F1
• 关键词: Reconstructing; wind; strength; atmospheric; circulation

Southern Ocean winds drive exchanges of heat and carbon dioxide between the ocean and the atmosphere, acting as a principal driver in regulating the global meridional overturning circulation. It is claimed that winds over the Southern Ocean (circumpolar westerlies) have increased in strength and shifted closer to the Antarctic continent in recent decades and is one of the strongest trends in Southern Hemisphere climate over the last 30 years. The enhanced circumpolar westerlies, attributed to greenhouse warming and anthropogenic ozone depletion, has driven changes in the depth of the ocean surface mixed layer and led to enhanced upwelling of deep, carbon-rich water. Regionally, changes in wind strength and atmospheric circulation patterns have been linked to the observed warming and increased precipitation on the Antarctica Peninsula and to increased upwelling of warm circumpolar deep water onto the Antarctic continental shelf. Circumpolar deep water promotes accelerated melting and thinning at the base of ice shelves and is considered a major contributing factor in the recent collapse of many Antarctic Peninsula ice shelves and a threat to the stability of large ice shelves in the Bellingshausen and Amundsen Sea. Few instrumental records of Southern Ocean winds exist prior to the late 20th century making it hard to validate models which examine the roles of wind strength and circulation on upwelling and climate. Climate models predict a poleward shift and strengthening of surface winds in response to increased atmospheric CO2 and therefore it is imperative that we understand how Southern Ocean wind patterns have changed over longer timescales and their potential impact on regional and ultimately global climate.In this proposal we will produce the first ice-core multi-proxy reconstruction of past wind strength and atmospheric circulation in the Bellingshausen and Amundsen Seas. The innovative proxy records will be developed using two new ice cores drilled on the climatically sensitive Amundsen Sea coast, West Antarctica which cover the period 2010-1700 AD. The unique discovery of marine diatoms in these ice cores, uplifted from the surface of the Amundsen/ Bellingshausen Sea and transported to the ice core sites by onshore (northerly) winds, will be used to provide a record of local changes in wind strength. This will be combined with records of dust and continental ions measured in the ice cores, which are proven proxies for long-range (circumpolar westerly) wind strength and circulation. Additional isotopic measurements will be taken to assess changes in the moisture source regions and the location of the Southern Hemisphere wind belt and a proven ice core proxy for past sea ice extent (Methansulphonic acid) will be measured to determine how sea ice influences uplift and transport of the diatoms deposited in the ice core.This interdisciplinary study will be the first of its kind to incorporate marine, continental and atmospheric tracers, to reconstruct both regional and hemispheric wind strength and atmospheric circulation in the Amundsen/Bellingshausen Sea. We will have an enhanced set of proxies to establish the drivers governing climate variability and an opportunity to explore the true impact of Southern Ocean winds on regional climate and upwelling in West Antarctica and the Amundsen/ Bellingshausen Sea. The new reconstructions will provide a much needed record of decadal to centennial changes and a means to test the intrinsic variability of climate models currently used to predict future climate change in this region.

南大洋风推动海洋和大气之间的热量和二氧化碳交换，是调节全球纬向翻转环流的主要驱动力。据称，近几十年来，南大洋上空的风（绕极西风）强度增加，并向南极大陆移动，这是过去30年来南半球气候最强烈的趋势之一。由于温室效应和人为臭氧消耗，环极西风增强，导致海洋表面混合层深度发生变化，并导致深层富碳水的上涌增加。在区域一级，风力和大气环流模式的变化与观测到的南极半岛变暖和降水量增加以及温暖的绕极深水向南极大陆架上涌的增加有关。极地周围的深水促使冰架底部加速融化和变薄，被认为是最近许多南极半岛冰架崩塌的一个主要因素，也是对别林斯高晋海和阿蒙森海大型冰架稳定性的一个威胁。在世纪后期之前，很少有南大洋风的仪器记录，这使得很难验证研究风强度和环流对上升流和气候的作用的模型。气候模型预测，随着大气中二氧化碳含量的增加，地表风将向极地移动并加强，因此，我们必须了解南大洋的风模式在较长时间尺度上是如何变化的，以及它们对区域乃至全球气候的潜在影响。别林斯高晋海和阿蒙森海过去风强度和大气环流的代用重建。创新的代理记录将使用两个新的冰芯钻在气候敏感的阿蒙森海海岸，南极洲西部，其中涵盖2010年至1700年的AD。这些冰芯是从阿蒙森/别林斯高晋海表面抬升并由陆上（偏北）风运送到冰芯地点的，在冰芯中发现的海洋硅藻是独一无二的，将被用来记录风力强度的局部变化。这将与冰芯中测量的尘埃和大陆离子的记录相结合，这些记录被证明是长距离（绕极西风）风强度和环流的代理。将进行额外的同位素测量，以评估水分源区的变化、南半球风带的位置以及过去海冰范围的已证实的冰芯替代物（甲磺酸）将被测量，以确定海冰如何影响沉积在冰芯中的硅藻的隆起和运输。这项跨学科的研究将是第一次将海洋，大陆和大气示踪剂，重建区域和半球风强度和大气环流在阿蒙森/别林斯高晋海。我们将有一套增强的替代指标来确定控制气候变化的驱动因素，并有机会探索南大洋风对南极洲西部和阿蒙森/别林斯高晋海区域气候和上升流的真正影响。新的重建将提供急需的十年至百年变化记录，并测试目前用于预测该地区未来气候变化的气候模型的内在变异性。

项目成果

Preliminary Evidence for the Role Played by South Westerly Wind Strength on the Marine Diatom Content of an Antarctic Peninsula Ice Core (1980-2010)

西南风强度对南极半岛冰芯海洋硅藻含量影响的初步证据（1980-2010）

• DOI: 10.3390/geosciences10030087
• 发表时间: 2020
• 期刊: Geosciences
• 影响因子: 2.7
• 作者: Allen C

Decadal Scale Variability of Larsen Ice Shelf Melt Captured by Antarctic Peninsula Ice Core

南极半岛冰芯捕获的拉森冰架融化的年代际尺度变化

• DOI: 10.3390/geosciences12090344
• 发表时间: 2022
• 期刊: Geosciences
• 影响因子: 2.7
• 作者: Emanuelsson B

Accumulation in coastal West Antarctic ice core records and the role of cyclone activity

• DOI: 10.1002/2017gl074722
• 发表时间: 2017-09
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: J. Hosking;R. Fogt;E. Thomas;V. Moosavi;T. Phillips;Jack H. J. Coggins;D. Reusch

Sea salt sodium record from Talos Dome (East Antarctica) as a potential proxy of the Antarctic past sea ice extent.

• DOI: 10.1016/j.chemosphere.2017.03.025
• 发表时间: 2017-06
• 期刊: Chemosphere
• 影响因子: 8.8
• 作者: M. Severi;S. Becagli;L. Caiazzo;V. Ciardini;Ester Colizza;F. Giardi;K. Mezgec;C. Scarchilli

Twentieth century increase in snowfall in coastal West Antarctica

• DOI: 10.1002/2015gl065750
• 发表时间: 2015-11-16
• 期刊: GEOPHYSICAL RESEARCH LETTERS
• 影响因子: 5.2
• 作者: Thomas, E. R.;Hosking, J. S.;Ludlow, E. C.
• 通讯作者: Ludlow, E. C.