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

摘要PI：Laurence Padman提案编号：0830398职务：SGER：斯科舍山脊西部ACC的直接跨坡通风智力价值：南极海洋&大气科学方案资助了这项题为“南极斜坡溪流交叉道路”的探索研究项目的小额赠款。这项研究将是美国对国际极地年（IPY）南极大陆架斜坡相互作用（SASSI）主题的更大背景的贡献。SASSI是一个组织结构，以整合南极大陆周围的研究，涉及到大陆架斜坡的相互作用，包括那些涉及到南极底层水的形成。 南极底层水驱动着全球纬向海洋环流的下肢，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将专门探讨直接通风的重要性，在附近的南斯科舍脊的深南极绕极流（ACC）相对于间接通风，通过向上混合的底部被困外流密集威德尔海深水。（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，但以前的区域研究（如国际鸽尾，1997-2000年和英国信天翁，1999年）的水文证据表明直接过程的可能性。此外，从声学和水文测量的逆建模和估计暗示非常高（2-3个数量级）的diapycnal混合率在这一地区。风应力或深海海流与地形或潮汐与地形的相互作用可能导致混合加剧。确定哪些通风机制占上风是重要的，了解全球气候变化，因为假设的直接通风机制应迅速响应不断变化的大陆架条件，如壮观的损失3200平方公里的部分拉森B冰架在2002年超过一个月。该项目将需要直接的小尺度湍流测量，从其中可以确定的diapycnal混合和驱动因素，混合可以在30天的巡航阿根廷RV波多黎各Deseado在2009年初进行评估。为该区域建立的潮汐模型将有助于指导取样，这反过来又有助于解决模型之间震级不一致的原因。一个单独的补充项目（Alejandro Orsi NSF-0818061）涵盖了水文和低声学多普勒海流测量以及西班牙资助的系泊设施加固，以量化南极斜坡流对直接通风的贡献。更广泛的影响：这个SGER项目将利用一个非凡的实地机会，利用国际和平年期间正在进行的一系列广泛的国际陆架-斜坡海洋环流研究。阿根廷合作社（ACROSS）、西班牙合作社（E-SASSI）和巴西合作社（SOS）的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，包括一个示踪剂计划，将有助于量化AABW的净通风率以及生物研究。 ACROSS还得到了美国IPY在更广泛地区的几项投资的进一步补充，包括与英国联合进行的美国Diapycnal Isopycnal Mixing Experiments（DIMES），对德雷克海峡南极绕极流的动力学和运输进行的深入研究，以及在南极半岛西部的帕尔默长期生态系统研究（LTER）站点进行的SASSI研究。还有许多其他国际努力正在进行中，作为SASSI伞的一部分。这些努力正在由国际南极区（iAnZone）小组协调，该小组是海洋研究科学委员会/南极研究科学委员会的附属方案。该提议将支助一名女技术员在海上操作剖面仪和处理数据。ACROSS微结构数据将经过处理，并通过国际SASSI和WOCE南大洋图集网站提供给国家和国际合作者。

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.