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

摘要PI：Laurence Padman建议编号：0830398标题：SGER：西斯科舍山脊ACC的直接跨坡通风智力价值：南极海洋和大气科学计划资助了这项名为南极坡流十字路口(Cross)的探险研究小赠款项目。这项研究将是美国对国际极年(IPY)南极陆架坡相互作用(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坡度相互作用有关的研究，包括与南极底水形成有关的研究。南极底层水驱动着全球经向海洋环流的下端，这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，以各种方式下沉或通风深海。现有信息表明，威德尔海地区贡献了南极底层水的50%左右。COVERS将具体探讨在南极绕极深海流(ACC)的南斯科舍海脊附近直接通风相对于通过向上混合密集的韦德尔海深水的底部陷阱流出的间接通风的重要性。(该区域其他国家的补充努力将提供信息，将深部行政协调委员会与AABW地层联系起来。)到目前为止，人们一直认为间接通风机制是成立的，但来自以前区域研究(例如，国际燕尾，1997-2000年和英国信天翁，1999年)的水文证据表明，直接过程是可能的。此外，声学和水文学测量的反向模拟和估计表明，该地区的昼夜混合率非常高(高出2-3个数量级)。高空混合可能是由风应力或深海洋流与地形或潮汐与地形的相互作用所驱动的。确定哪种通风机制对了解全球气候变化很重要，因为假设的直接通风机制应该对不断变化的大陆架条件作出相当迅速的反应，例如2002年拉森B冰架一个月来3200平方公里的显著损失。该项目将需要直接进行小规模湍流测量，从中可以确定日混合，并可以在2009年初阿根廷房车波多黎各Deseado的30天游轮上评估驱动混合的因素。为该地区建立的潮汐模型将有助于指导采样，这反过来又有助于解决模型之间量值不一致的原因。另一个补充项目(Alejandro Orsi NSF-0818061)涵盖了水文测量和降低的声学多普勒流测量以及由西班牙资助以量化南极坡流对直接通风的贡献的系泊设施。更广泛的影响：SGER项目将利用一个非同寻常的实地机会，利用在国际海洋年期间开展的一系列广泛的国际陆架-斜坡海洋环流研究。阿根廷(横跨)、西班牙(E-Sassi)和巴西(SOS)的合作努力集中在本研究的具体区域。该合作提供了更广泛的区域覆盖范围，并包括一个示踪剂计划，该计划将有助于量化AABW的净通气率以及生物学研究。此外，美国IPY还在更广泛的区域内进行了几项投资，包括与英国联合开展的美国南极环极混合实验(DIMES)、对德雷克海峡南极绕极洋流的动态和输送的深入研究，以及在南极半岛西部死地的帕尔默长期生态系统研究(LTER)场地进行的SASSI研究。作为萨西保护伞的一部分，还有许多其他国际努力正在进行中。这种努力正在由国际南极区域(IAnZone)小组协调，该小组是SCOR/SCAR(海洋研究科学委员会/南极研究科学委员会)的附属项目。这项提议将支持一名女性技术人员在海上操作剖面仪并处理数据。将对跨微结构数据进行处理，并通过SASSI和WOCE南大洋地图集的国际网站向国家和国际合作者提供。

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.