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

南大洋风推动海洋和大气之间的热量和二氧化碳交换，是调节全球经向颠覆环流的主要驱动力。据称，近几十年来，南大洋(环极西风带)上的风强度增加，并向南极大陆靠拢，是近30年来南半球气候变化最强劲的趋势之一。极地西风增强，归因于温室效应和人为臭氧消耗，推动了海洋表面混合层深度的变化，并导致富含碳的深层水的上升流增强。在区域上，风力和大气环流模式的变化与观察到的南极半岛变暖和降水增加以及温暖的绕极深水上升到南极大陆架有关。环极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坍塌的主要促成因素，并威胁到别林豪森和阿蒙森海大型冰架的稳定性。在20世纪末之前，关于南大洋风的仪器记录很少，这使得检验风强度和环流对上升流和气候的作用的模型很难得到验证。气候模型预测，随着大气二氧化碳的增加，地面风将向极地转移和加强，因此，我们必须了解南大洋风型在较长时间尺度上是如何变化的，以及它们对区域和最终全球气候的潜在影响。在这项提议中，我们将首次对别林豪森和阿蒙森海过去的风强度和大气环流进行冰芯多代理重建。创新的替代记录将使用在气候敏感的南极洲西部阿蒙森海海岸钻探的两个新冰芯来开发，覆盖公元2010-1700年期间。在这些冰芯中发现独特的海洋硅藻，从阿蒙森/贝灵豪森海面上抬起，通过陆上(偏北)风输送到冰芯地点，将被用来记录当地风力的变化。这将与在冰芯中测量的尘埃和大陆离子的记录结合在一起，这些记录被证明是远程(绕极西风)风力和环流的替代指标。将进行更多的同位素测量，以评估水汽源区的变化和南半球风带的位置，并将测量已证实的反映过去海冰范围的冰芯替代物(甲基磺酸)，以确定海冰如何影响沉积在冰芯中的硅藻的抬升和运输。这项跨学科研究将首次纳入海洋、大陆和大气示踪剂，以重建阿蒙森/贝灵豪森海的区域和半球风力强度和大气环流。我们将拥有一套增强的指标，以确定支配气候变异性的驱动因素，并有机会探索南大洋风对南极洲西部和阿蒙森/贝灵豪森海的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到百年变化的记录，并提供一种手段来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可变性。

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.