Towards two decades of ocean mass and heat transports at 26.5N: Extension of the RAPID-MOCHA Array

迈向二十年 26.5N 海洋质量和热量传输：RAPID-MOCHA 阵列的扩展

• 批准号: 2148723
• 负责人: William Johns
• 金额: $ 308.46万
• 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: 2022
• 资助国家: 美国
• 起止时间: 2022-03-15 至 2027-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2148723&HistoricalAwards=false
• 关键词: Towards; two; decades; ocean; mass

Climate models suggest that variability of the Atlantic meridional overturning circulation (AMOC) is linked to sea surface temperature changes on interannual to multi-decadal time scales that can have far reaching societal impacts. Additionally, climate models continue to project a substantial weakening of the AMOC over the next century that could feed back on the climate system through reduced northward heat transport as well as reduced CO2 uptake in the North Atlantic. The specific role of the AMOC in the climate system has been difficult to determine due to a lack of long term measurements of its variability. At the end of its current phase, the RAPID-MOCHA observing system along 26.5°N will have provided continuous estimates of the AMOC for just under 19 years, the longest full-depth, basinwide measurements of oceanic transport currently available. These observations have provided a critical benchmark for the evaluation of forced, data-assimilative, and coupled climate models, and have formed a fundamental building block around which international programs are being developed to monitor the AMOC throughout the Atlantic basin. This project will continue the U. S. contribution to RAPID-MOCHA for an additional 42 months, from January 2023 to June 2026, extending the time series of oceanic mass, heat, and freshwater transports to 22.3 years. The results from this program will continue to provide oceanic observations crucial for the assessment and improvement of forced, data-assimilative, and coupled climate models. The proposed program continues a successful collaborative effort between the P.I.'s and investigators from the U.K. National Oceanography Centre, who are submitting a companion proposal to maintain their part of the observing system for the same time period through U.K. funding sources. The program also collaborates with NOAA AOML in their Western Boundary Time Series program, and provides training for graduate students and postdoctoral researchersThe U.S. contribution to the in-situ observation system includes: (1) Florida Current monitoring using a submarine cable, calibrated by regular cruises with hydrographic and velocity measurements, and (2) continuous moored time series measurements within the Deep Western Boundary Current and Antilles Current region east of the Bahamas, including hydrographic and velocity sections at approximately 11-month intervals. The maintenance of the repeat hydrographic sections will be conducted in collaboration with NOAA which also supports independently the Florida Current monitoring. U.K. collaborators will provide support for the eastern basin moorings that complete the 26.5°N trans-basin time series observing system. Limited new instrumentations on moorings will also be included to derive ocean bottom pressure gradient on the boundary east of the Bahamas. The RAPID-MOCHA observations will allow the team to document and understand the causes and impacts of the AMOC interannual to decadal variability, to investigate the control of western boundary pressure on transports, and to link changes observed at 26.5°N to other AMOC indices and results from on-going AMOC measurement programs around the Atlantic basin. By quantifying the interannual to decadal variability of the meridional circulations of mass, heat, and freshwater in the North Atlantic Ocean at 26.5°N, this project will further contribute to the understanding of the processes leading to changes of sea surface temperature, air-sea fluxes, and ocean heat and freshwater storage that are integral components of the North Atlantic regional climate and global climate. The time series so far have shown a longer-term decline with respect to the early years of the program, the origin of which---natural variability or response to anthropogenic climate change---is yet to be determined from longer observations. The AMOC constitutes a relative rapid conduit between the atmosphere and the deep ocean that is crucial to continuously observe on climate-relevant temporal scales to understand the ramifications of anthropogenically-forced climate change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

气候模型表明，大西洋经向翻转环流的变化与海表面温度在年际到数十年的时间尺度上的变化有关，这可能会产生深远的社会影响。此外，气候模型继续预测，在下个世纪，AMOC将大幅减弱，这可能会通过减少向北的热量输送以及减少北大西洋的二氧化碳吸收来反馈气候系统。由于缺乏对其可变性的长期测量，很难确定AMOC在气候系统中的具体作用。在本阶段结束时，26.5°N沿线的快速MOCHA观测系统将提供近19年的AMOC的连续估计，这是目前可获得的对海洋运输的最长全深度、全盆地范围的测量。这些观测为强迫、数据同化和耦合气候模式的评估提供了一个关键基准，并形成了一个基本的基石，围绕着它正在制定国际计划，以监测整个大西洋盆地的AMOC。从2023年1月到2026年6月，该项目将继续美国对快速莫卡的贡献42个月，将海洋质量、热量和淡水传输的时间序列延长到22.3年。该计划的结果将继续提供对评估和改进强迫的、数据同化的和耦合的气候模型至关重要的海洋观测。拟议中的项目延续了私家侦探S和英国国家海洋学中心的研究人员之间的成功合作努力，后者正在提交一份配套提案，通过英国的资金来源在同一时间段内维护他们所在的观测系统。该项目还与NOAA AOML合作开展西部边界时间序列项目，并为研究生和博士后研究人员提供培训。美国对现场观测系统的贡献包括：(1)使用海底电缆进行佛罗里达海流监测，通过定期巡航进行水文和流速测量校准；(2)在巴哈马以东的西部深层边界洋流和安的列斯洋流区域内进行连续系泊时间序列测量，包括大约每隔11个月进行一次的水文和速度剖面测量。重复水文区段的维护将与NOAA合作进行，NOAA也独立支持佛罗里达州的海流监测。英国的合作者将为东部盆地的系泊设施提供支持，以完成26.5°N跨盆地时间序列观测系统。还将包括有限的系泊新仪器，以求取巴哈马以东边界的海底压力梯度。快速MOCHA观测将使团队能够记录和了解AMOC年际至年代际变化的原因和影响，调查西部边界压力对运输的控制，并将在26.5°N观察到的变化与其他AMOC指数和大西洋盆地周围正在进行的AMOC测量项目的结果联系起来。通过量化北大西洋26.5°N质量、热量和淡水经向环流的年际至年代际变化，该项目将进一步有助于理解导致北大西洋区域气候和全球气候组成部分的海表面温度、海气通量、海洋热量和淡水储存变化的过程。到目前为止，时间序列显示出相对于该计划最初几年的较长期下降，其来源-自然变异性或对人为气候变化的反应-尚未通过更长时间的观察来确定。AMOC构成了大气和深海之间相对快速的管道，对于在与气候相关的时间尺度上持续观察以了解人类强迫气候变化的后果至关重要。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Atlantic Meridional Overturning Circulation (AMOC) Heat Transport Time Series between April 2004 and December 2020 at 26.5°N

2004 年 4 月至 2020 年 12 月 26.5°N 的大西洋经向翻转环流 (AMOC) 热传输时间序列

• DOI: 10.17604/3nfq-va20
• 发表时间: 2023
• 期刊: University of Miami Libraries
• 作者: Johns, William;Elipot, Shane;Smeed, David;Moat, Ben;KING, Brian;Volkov, Denis;Smith, Ryan
• 通讯作者: Smith, Ryan