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：Laurence PadmanPropopals编号：0830398TITLE：SGER：西部斯科舍省西部ACC的直接交叉斜坡通风：南极海洋与大气科学计划资助了这项为探索性研究项目的小型拨款提供资助，用于探索性研究项目，该项目具有Slope Streams的探索性研究项目。这项研究将是美国对国际极性年（IPY）概要南极斜坡相互作用（SASSI）主题的贡献。萨西（Sassi）是一种组织结构，旨在整合与架子斜率相互作用有关的南极大陆周围的研究，包括与南极底水的形成有关的研究。 南极底水驱动全球子午海洋循环的下肢，有助于调节全球气候。南极货架上的相互作用形成密集的水，以多种方式沉入或通风深海。 可用的信息表明，韦德尔海地区约有50％的南极底水。 各地将特别探讨直接通风在南卡省南极山脊附近的重要性，相对于间接通风，通过向上混合底部茂密的Weddell Sea Deep Water的流出，相对于间接通风。 （该地区其他人的互补努力将提供将深度ACC与AABW组联系起来的信息。）直到现在，已经假定通风的间接机制持有，但是先前区域研究的水文证据（例如，International Dovetail，1997-2000和UK Albatross，1999年）暗示了直接流程的可能性。此外，声学和水文测量结果的反向建模和估计暗暗在该区域中极高的（通过2-3个数量级）的二体混合速率。升高的混合可能是由风应力或深渊电流与地形或地形潮流的相互作用驱动的。确定哪种通风机制对于理解全球气候变化很重要，因为假定的直接通风机制应应对不断变化的货架状况的反应，例如2002年在一个月内，Larsen B ICE货架的3200 km2段的巨大损失，该项目将需要在该项目中进行直接计量的脉动测量，从而在该项目中评估了30次驾驶范围的驾驶范围，以确定的混合限制，并确定要驾驶的混合，以使某种情况下的混合驱动因素，以使某种情况下的混合驱动因素，而驱动驱动因素，而该项目的混合因素是驱动的。阿根廷RV波多黎各Deseado于2009年初。该地区建立的潮汐模型将有助于指导采样，进而有助于解决模型之间幅度不一致的原因。水文和降低的声学多普勒电流测量值以及西班牙资助以实现南极斜率电流对直接通气的贡献的系泊的增强（Alejandro Orsi nsf-0818061）涵盖了对直接通气的定量。更广泛的影响：这个SGER项目将利用一个非凡的现场机会，利用在IPY期间进行的一系列国际货架斜坡循环研究。阿根廷合作社（跨越），西班牙（E-Sassi）和巴西（SOS）努力集中在本研究的特定地区。该合作提供了更广泛的区域覆盖范围，并包括一个示踪计划，该计划将有助于量化AABW的净通风率以及生物学研究。 与英国联合的几项美国杂志等区域中，包括美国二比等异，等级混合实验（DIMES），这是与英国联合的，对Drake Passage中南极循环电流的动态和运输进行了深入研究，以及在Palmer长期生态学研究（LTER）上的SASSI研究中，对整个地区进行了补充。作为萨西伞的一部分，还有许多其他国际努力正在进行中。这种努力正在协调国际南极区（Ianzone）小组，该小组是SCOR/SCOR（海洋研究/南极研究科学委员会科学委员会）附属计划。该建议将支持一名女技术员在海上运行探查器并处理数据。跨微观结构数据将通过国际Sassi和Woce Southern Atlas网站进行处理并提供给国家和国际合作者。