Agulhas System Climate Array (ASCA)

厄加勒斯系统气候阵列 (ASCA)

• 批准号: 1459543
• 负责人: Lisa Beal
• 金额: $ 206.44万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2022-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1459543&HistoricalAwards=false
• 关键词: Agulhas; System; Climate; Array; ASCA

The Agulhas Current is the western boundary current of the South Indian Ocean subtropical gyre and, as such, it dominates the heat budget of the Indian Ocean basin. Variability in sea surface temperature and heat content is central to many aspects of climate over the Indian Ocean basin, such as East African rainfall, tropical cyclone activity, and sea level rise. More than 50% of decadal Sea Surface Temperature variability over the Indian Ocean is explained by uniform, basinwide warming or cooling and it is hypothesized that this could be linked to changes in the meridional overturning circulation. Understanding the links between Indian Ocean overturning, meridional heat transport and sea surface temperature is currently hampered by lack of observations. Estimates of the Indian Ocean meridional overturning circulation have been made less than a handful of times over the past 50 years. Yet, one can expect its short-term variability to exceed the span of these few estimates, just as it does in the Atlantic. The poleward heat transport that exits the Indian Ocean via the Agulhas Current feeds both northward into the Atlantic, where it is believed to influence meridional overturning and hence climate in that basin, and southward into the Southern Ocean. Measuring Agulhas variability and investigating its relationship to wind forcing and Agulhas leakage proxies will lead to a better understanding of how these phenomena are linked in the real ocean. An integral component of this project is to provide skills-transfer to South African scientists and technicians so that they can lead and sustain an Agulhas array in the longer term. Resource sharing, capacity building, an open data policy, and collaborative analyses will promote greater productivity and better quality research from the western Indian Ocean oceanographic community in general. The principal investigator will be a visiting Professor at the University of Cape Town in 2015 and 2018 and teach a 2-week Honors module on large-scale dynamical oceanography, as part of this project. A U.S. graduate student, a postdoctoral researcher and an early career scientist will be trained. The Agulhas System Climate Array (ASCA) project is a collaboration between South African, Dutch, and US scientists to implement sustained observations of the Agulhas Current, as part of the Global Ocean Observing System. This five-year phase for ASCA will establish measurements of velocity, temperature, and salinity variability in the Current, including its influence on coastal waters. These measurements will be synthesized with satellite and Argo data to achieve the following major scientific objectives:(1) Characterize the relationship between volume and temperature transport in the Agulhas Current.(2) Quantify the seasonal variability in basin-wide overturning and heat transports of the Indian Ocean, by synthesizing ASCA measurements with Argo and satellite data over the ocean interior.(3) Investigate the annual and interannual variability of the Agulhas Current in the context of wind forcing and changes in retroflection and leakage.Three ASCA research cruises (2016, 2018 and 2019) will take place aboard South African research vessels, during which the international team will deploy and maintain a linear array of seven full-depth current meter moorings with additional temperature and salinity sensors interspersed with four bottom-mounted Current and Pressure-sensing Inverted Echo Sounders. Finally, three coastal moorings will be added to the array at the shelf break and inshore, all in less than 200 m of water. These are led by the South African partners, whose motivation is to study the regional impact of Agulhas Current variability on coastal currents, upwelling, and the annual sardine run. During deployment and recovery of the mooring, hydrographic sections across the Agulhas Current near 34◦S will be collected. The sampling plan is based on moored velocity observations that have been successfully collected before in this location under the Agulhas Current Time-series experiment funded by NSF. This project is a contribution to the U.S. CLIVAR (CLImate VARiability and predictability) program.

阿古拉斯流是南印度洋副热带环流的西边界流，因此它支配着印度洋盆地的热收支。海面温度和热含量的变化对印度洋盆地气候的许多方面都至关重要，例如东非降雨、热带气旋活动和海平面上升。印度洋上超过50%的年代际海表温度变化可以用均匀的全盆地变暖或变冷来解释，据推测，这可能与经向翻转环流的变化有关。了解印度洋翻转、经向热输运和海面温度之间的联系目前由于缺乏观测而受到阻碍。在过去的50年里，对印度洋经向翻转环流的估计只有寥寥几次。然而，我们可以预期它的短期变化会超过这几个估计的跨度，就像在大西洋一样。经由阿古拉斯海流离开印度洋的极向热输送向北进入大西洋，据信它会影响经向翻转，从而影响大西洋盆地的气候，并向南进入南大洋。测量Agulhas变率并研究其与风强迫和Agulhas泄漏代理的关系将使人们更好地了解这些现象在真实海洋中的联系。这个项目的一个组成部分是向南非科学家和技术人员提供技能转让，以便他们能够长期领导和维持Agulhas阵列。资源共享、能力建设、开放数据政策和协作分析将促进整个西印度洋海洋学界提高生产力和提高研究质量。作为该项目的一部分，首席研究员将于2015年和2018年在开普敦大学担任客座教授，并教授为期两周的大规模动态海洋学荣誉模块。将培养一名美国研究生、一名博士后研究员和一名早期职业科学家。阿古拉斯系统气候阵列（ASCA）项目是南非、荷兰和美国科学家之间的一个合作项目，旨在实施对阿古拉斯洋流的持续观测，作为全球海洋观测系统的一部分。ASCA的这个五年阶段将建立洋流速度、温度和盐度变化的测量，包括其对沿海水域的影响。这些测量结果将与卫星和Argo数据合成，以实现以下主要科学目标：(1)表征阿古拉斯海流体积和温度传输之间的关系。(2)通过Argo和海洋内部卫星数据综合ASCA测量数据，量化印度洋全流域翻转和热输送的季节变化。(3)在风强迫、反射和渗漏变化的背景下，研究阿古拉斯海流的年际变化。三次ASCA研究巡航（2016年、2018年和2019年）将在南非的研究船上进行，在此期间，国际团队将部署和维护一个由七个全深度流计系泊组成的线性阵列，其中有额外的温度和盐度传感器，以及四个底部安装的电流和压力传感反向回声测深仪。最后，三个海岸系泊将被添加到陆架断裂和近岸的阵列中，所有系泊都在不到200米的水中。这些项目由南非合作伙伴牵头，其动机是研究阿古拉斯海流变化对沿海洋流、上升流和每年沙丁鱼洄游的区域影响。在部署和恢复系泊期间，Agulhas海流附近34&amp；#9702的水文剖面；S将被收取。采样计划是基于之前在美国国家科学基金会资助的Agulhas Current Time-series实验下在该地点成功收集的系泊速度观测数据。该项目是对美国CLIVAR（气候变率和可预测性）计划的贡献。