SGER: Direct Cross-Slope Ventilation of the ACC at the Western Scotia Ridge

SGER：西斯科舍山脊 ACC 的直接横向斜坡通风

• 批准号: 0830398
• 负责人: Laurence Padman
• 金额: $ 4.98万
• 依托单位: Earth and Space Research
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0830398&HistoricalAwards=false
• 关键词: SGER; Direct; Cross; Slope; Ventilation

AbstractPI: Laurence PadmanProposal Number: 0830398Title: SGER: Direct Cross-Slope Ventilation of the ACC at the Western Scotia RidgeIntellectual merit: The Antarctic Ocean & Atmospheric Sciences Program funded this Small Grant for Exploratory Research project entitled Antarctic CRossroads Of Slope Streams (ACROSS). This study will be a US contribution to the larger context of the International Polar Year (IPY) Synoptic Antarctic Shelf Slope Interactions (SASSI) theme. SASSI is an organizational structure to integrate studies around the Antarctic continent that pertain to the shelf slope interactions including those that pertain to formation of Antarctic Bottom Water. Antarctic Bottom Water drives the lower limb of global meridional ocean circulation that helps to regulate global climate. Interactions on Antarctic shelves form dense water which sinks or ventilates the deep ocean in a variety of ways. Available information suggests that the Weddell Sea region contributes about 50% of Antarctic Bottom Water. ACROSS will specifically explore the importance of direct ventilation in the vicinity of the South Scotia Ridge of the deep Antarctic Circumpolar Current (ACC) relative to indirect ventilation through upward mixing of bottom-trapped outflows of dense Weddell Sea Deep Water. (Complementary efforts by others in the region will provide information linking the deep ACC to AABW formation.) Until now, it has been presumed that the indirect mechanism of ventilation holds but hydrographic evidence from previous regional studies (e.g. international DOVETAIL, 1997-2000 and UK ALBATROSS, 1999) suggests the possibility of the direct processes. Furthermore, inverse modeling and estimates from acoustic and hydrographic measurements implicate extraordinarily high (by 2-3 orders of magnitude) diapycnal mixing rates in this region. Elevated mixing may be driven by wind stress or the interactions of abyssal currents with topography or tides with topography. Determining which ventilation mechanisms prevail is important for understanding global climate change since the hypothesized direct ventilation mechanism should respond quite rapidly to changing shelf conditions such as the spectacular loss of a 3200 km2 section of the Larsen B Ice Shelf over one month in 2002. This project will entail direct small scale turbulence measurements from which diapycnal mixing can be determined and factors driving that mixing can be evaluated on a 30 day cruise of the Argentine RV Puerto Deseado in early 2009. Established tidal models for the region will help guide sampling, which in turn should help to resolve the reasons for inconsistent magnitudes between the models. Hydrographic and lowered acoustic Doppler current measurements as well as augmentation of moorings funded by the Spanish to achieve quantification of the Antarctic Slope Current contribution to direct ventilation are covered in a separate complementary project (Alejandro Orsi NSF-0818061). Broader impacts: This SGER project will take advantage of an extraordinary field opportunity that leverages a broad array of international shelf-slope ocean circulation studies being carried out during the IPY. Cooperative Argentine (ACROSS), Spanish (E-SASSI) and Brazilian (SOS) efforts are focused in the specific region of this study. The cooperation affords broader regional coverage and includes a tracer program that will help to quantify the net ventilation rates of AABW as well as biological studies. ACROSS is further complemented by several US IPY investments in broader region including the US Diapycnal Isopycnal Mixing Experiments (DIMES) that is joint with the UK, an intensive study of the dynamics and transport of the Antarctic Circumpolar Current in the Drake Passage and a SASSI study in the Palmer Long Term Ecosystem Research (LTER) site on the western dies of the Antarctic Peninsula. There are numerous other international efforts that are underway as part of the SASSI umbrella. Such efforts are being coordinated the international Antarctic Zone (iAnZone) group, which is a SCOR/SCAR (Scientific Committee for Ocean Research/Scientific Committee for Antarctic Research) affiliated program. A female technician will be supported by this proposal to run the profiler at sea and to process the data. The ACROSS microstructure data will be processed and made available to national and international collaborators via the international SASSI and WOCE Southern Ocean Atlas web sites.

摘要 PI：劳伦斯·帕德曼提案编号：0830398标题：SGER：西斯科舍山脊 ACC 的直接交叉斜坡通风智力价值：南极海洋与大气科学计划资助了这项名为南极斜坡溪流交叉路（ACROSS）的探索性研究项目小额赠款。这项研究将是美国对国际极地年（IPY）天气南极陆架斜坡相互作用（SASSI）主题的更大背景的贡献。 SASSI 是一个组织结构，旨在整合南极大陆周围与陆架斜坡相互作用相关的研究，包括与南极底水形成相关的研究。 南极底层水驱动全球经向海洋环流的下肢，有助于调节全球气候。南极大陆架上的相互作用形成了稠密的水，这些水以各种方式下沉或使深海通风。 现有信息表明，威德尔海地区贡献了约 50% 的南极底层水。 ACROSS 将专门探讨南极绕极流 (ACC) 南斯科舍海脊附近直接通风的重要性，相对于通过向上混合浓密威德尔海深水底部截流流出的间接通风的重要性。 （该地区其他人的补充努力将提供将深层 ACC 与 AABW 形成联系起来的信息。）到目前为止，人们一直认为通风的间接机制成立，但来自先前区域研究的水文证据（例如国际 DOVETAIL，1997-2000 和UK ALBATROSS，1999）提出了直接过程的可能性。此外，根据声学和水文学测量进行的逆向建模和估计表明该区域的地下混合率非常高（2-3 个数量级）。高度混合可能是由风应力或深海流与地形或潮汐与地形的相互作用驱动的。确定哪种通风机制占主导地位对于理解全球气候变化非常重要，因为假设的直接通风机制应该对不断变化的陆架条件做出相当迅速的反应，例如 2002 年一个月内拉森 B 冰架 3200 平方公里部分的巨大损失。该项目将需要直接的小规模湍流测量，从中可以确定二重混合，并可以在阿根廷 RV Puerto Deseado 的 30 天巡航中评估驱动混合的因素2009年。为该地区建立的潮汐模型将有助于指导采样，这反过来又应有助于解决模型之间震级不一致的原因。水道测量和降低声学多普勒电流测量以及由西班牙资助的系泊装置的增强，以实现南极坡流对直接通风的贡献的量化，包含在一个单独的补充项目（Alejandro Orsi NSF-0818061）中。更广泛的影响：该 SGER 项目将利用一个非凡的实地机会，利用 IPY 期间开展的一系列国际陆架斜坡海洋环流研究。阿根廷（ACROSS）、西班牙（E-SASSI）和巴西（SOS）的合作努力集中在本研究的特定区域。该合作提供了更广泛的区域覆盖范围，并包括一个追踪计划，该计划将有助于量化 AABW 的净通风率以及生物学研究。 ACROSS 得到了美国在更广泛地区的多项 IPY 投资的进一步补充，包括与英国联合进行的美国双重等重混合实验 (DIMES)、对德雷克海峡南极绕极流动力学和传输的深入研究以及 SASSI 研究位于南极半岛西部的帕尔默长期生态系统研究（LTER）站点。作为 SASSI 框架的一部分，还有许多其他国际努力正在进行中。这些工作正在国际南极区 (iAnZone) 小组的协调下进行，该小组是 SCOR/SCAR（海洋研究科学委员会/南极研究科学委员会）的附属计划。该提案将支持一名女性技术人员在海上运行剖面仪并处理数据。 ACROSS 微观结构数据将经过处理并通过国际 SASSI 和 WOCE 南大洋地图集网站提供给国内和国际合作者。