Subantarctic Mode Water and Antarctic Intermediate Water mass formation and distribution: an observational-model synthesis using a Southern Ocean state estimate

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。南极中层水域(AAIW)是最稠密的环极亚南极模式水域(SAMW)。AAIW填满了800米至1000米深的南半球和世界热带海洋。这些水域在全球淡水收支中很重要，并可能通过影响北大西洋深水(NADW)的形成来影响长期气候变异性。太平洋AAIW年代际变化可能与人为气候变化有关。AAIW影响热带海洋的层结，因此AAIW的变化可能影响厄尔尼诺/南方涛动的变化。智力上的优点。该项目的中心目标是在涡旋分辨南大洋状态估计(SOSE)中表征和量化亚南极模式水和南极中间水的形成，描述它们在涡旋到全球横向尺度上在SOSE海洋内部的路径，将结果与观测结果进行比较，并确定SAMW和AAIW形成的关键过程和位置，以支持组织未来的实地工作。这项工作还将包括评估估计的大气强迫场的保真度，特别是在较小的(中)尺度上。调查人员将综合以前和正在进行的项目的结果，重点是南大洋模式和中间水域观测和模式结果。有两年(2005年和2006年)的涡旋允许(1/6°水平分辨率)南大洋状态估计(SOSE)同化观测，包括来自东南太平洋模式水形成区最近两次游轮的观测。SOSE允许将南大洋水团在海洋内部形成和扩散的观测图片与数值(同化)海洋中的图片进行比较，该数值(同化)海洋具有前所未有的横向分辨率和海气强迫的真实性。SOSE同化地表通量，但将其调整为与海场动态一致，均具有1/6°的水平分辨率。研究人员已将SOSE海气通量的大尺度模式与文献中的结果进行了详细的比较，发现它们比以往的通量产品有了显著的改进，并开始了对SOSE水团的研究，结果表明，与标准的NWP通量产品相比，SOSE通量更真实地捕捉到了形成SAMW/AAIW的密度范围。在不同的南大洋环流数值模式中对平均流和涡动动力学进行相关研究，将有机会将南大洋环流的水团性质和分布与分辨率相当的独立海洋模式中的水团性质和分布进行比较。联合PI，Tley教授将领导合成SAMW和AAIW的观测和模型结果。作为由另一个项目资助的斯克里普斯海洋研究所的新博士后，马兹洛夫博士将继续进行SOSE同化，在时间和数据覆盖范围上扩展它。布罗德影响：这项分析将详细记录南大洋环流的SOSE数值表示及其对应的海洋表面迫力场的水文特性，并与现有的观测和文献进行比较。这些结果将成为(1)规划和评价新的观测性研究，以及(2)规划和评价新的海洋和(或)海洋-大气模式研究的基础，特别是旨在评价南大洋过程和/或变化对气候的影响的研究。所有SOSE字段都是公开可用的。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Antarctic Intermediate Water (AAIW) is the densest of circumpolar Subantarctic Mode Waters (SAMW). AAIW fills the southern hemisphere and world tropical oceans at depths of 800 m to 1000 m. These waters are important in the global freshwater budget and may impact long-term climate variability through their influence on North Atlantic Deep Water (NADW) formation. Decadal freshening of Pacific AAIW may be associated with anthropogenic climate change. AAIW affects the stratification of the tropical ocean, and variability in AAIW may thus influence variations in the El Niño/Southern Oscillation. INTELLECTUAL MERIT. The central goal of this project is to characterize and quantify the formation of Subantarctic Mode Water and Antarctic Intermediate Water in an eddy resolving Southern Ocean State Estimate (SOSE), to describe their pathways in the SOSE ocean interior at eddy to global lateral scales, to compare the results with the observations, and to identify key processes and locations for SAMW and AAIW formation in support of organizing future fieldwork. The work will also include assessing the fidelity of estimated atmospheric forcing fields, especially at smaller (meso) scales. The investigators will synthesize the results of previous and ongoing projects, focusing on Southern Ocean mode and intermediate water observations and model results. Two years (2005 and 2006) of an eddy permitting (1/6° horizontal resolution) Southern Ocean State Estimate (SOSE) that assimilates observations, including those from two recently cruises in the southeastern Pacific mode water formation region, are available. SOSE permits comparison of the observational (cruise-based) picture of Southern Ocean water mass formation and spreading in the ocean interior with that in a numerical (assimilating) ocean of unprecedented lateral resolution and realism of air-sea forcing. SOSE assimilates surface fluxes, but adjusts them to be dynamically consistent with the oceanic fields, all with horizontal resolution of 1/6°. The investigators have completed a detailed comparison of large scale pattern of SOSE air-sea fluxes with those in the literature, finding them to be a notable improvement over previous flux products, and has also begun a study of water masses in SOSE, which shows that the SOSE fluxes more faithfully capture the density ranges within which SAMW/AAIW is formed than do the standard NWP flux products. A related study of mean flow and eddy dynamics in a different numerical model of Southern Ocean circulation will provides the opportunity to compare water mass properties and distributions in SOSE with those in a stand-alone ocean model of comparable resolution. The co-PI, Professor Talley will provide leadership in synthesizing SAMW and AAIW observations and model results. As a new post-doc at Scripps Institution of Oceanography funded through another project, Dr. Mazloff will continue the SOSE assimilation, extending it in time and data coverage.BROADER IMPACTS: This analysis will document in detail the hydrographic properties of the SOSE numerical representations of Southern Ocean circulation and of their corresponding ocean surface forcing fields in comparison with existing observations and literature. The results will be a foundation upon which to (i) plan and evaluate new observational studies, and to (ii) plan and evaluate new ocean and or ocean-atmosphere model studies, particularly studies intended to evaluate the effects of processes and/or changes in the Southern Ocean on climate. All SOSE fields are publicly available.