Calibrated pCO2 in air and surface ocean Sensor for ASVs (CaPASOS)

用于 ASV (CaPASOS) 的空气和海洋表面校准 pCO2 传感器

• 批准号: NE/P020755/1
• 负责人: Andrew Watson
• 金额: $ 54.22万
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FP020755%2F1
• 关键词: Calibrated; pCO2; air; surface; ocean

The human emission of carbon dioxide, largely from fossil fuel burning, will continue for the foreseeable future to be the most important cause of climate change. Only about half of our emissions are remaining in the atmosphere however. The other half is being absorbed, it is believed, in approximately equal amounts by vegetation on land and uptake by the ocean. These "natural sinks" of CO2 are consequently of huge value to us, since they slow the progress of climate change, so their present operation, and possible changes future uptake of CO2, are a focus of intense research. The sink of CO2 into the ocean is today being observed by measurements of atmospheric and sea surface pCO2, the partial pressure of CO2 at the surface of the ocean. This controls the rate at which CO2 exchanges between the ocean and atmosphere, and which for this reason has been designated an "essential ocean variable" by the Global Ocean Observing System. These observations are usually made from commercial vessels, and where there are busy shipping routes, for example in much of the Atlantic and North Pacific Oceans, there are sufficient observations to describe the air-sea flux. However, there are other very large regions (the Indian, South Pacific and Southern Oceans for example) where we have woefully insufficient data. In the future, this need could be met by autonomous surface vehicles (ASVs) making pCO2 measurements, and our proposal is to develop a pCO2 sensor specifically designed for ASVs. It will follow protocols that have been established by international bodies for the highest quality measurements suited to calculating the air-sea flux of carbon dioxide in the open ocean. The technical challenge is to adapt the successful principles of the instruments mounted in ships or on large buoys, where space and power are not limiting factors, to achieve the same high accuracy with small space and power footprint, resistance to violent motion, and long endurance, necessary on an ASV. We will achieve this by bringing together the extensive experience that the Exeter University group has in operating ship-based CO2 systems over 20 years, with improvements in engineering, utilising the experience and expertise of the NOC Technology and Engineering groups. We will use the basic measurement technique that has been well tested on the large instruments (equiibration of water with gas, and measurement of CO2 in gas by non-dispersive infra-red detection). However, we will use miniaturised components having small volumes and low flow rates of gas, enabling even a small instrument to carry on-board calibration gases. The specifications of the final instrument will include: endurance of up to a year and with frequency of measurements (both surface water and atmosphere) sufficient to define daily cycles, regular calibration using on-board calibration gases stored in miniature compressed gas cylinders, and measurement of CO2 in dried air which has equilibrated with surface water by direct contact. The instrument will also conform to data standards and integration protocols to enable the ready integration and exchange of sensors into autonomous platforms.A laboratory prototype exists, built by U. Exeter. To achieve our main objective, our sub-objectives are: 1) Development of second generation and deployment alongside a shipboard instrument and testing at coastal sites (2) modification and deployment on a mooring at the Western Channel Observatory for an extended period (3) Construction of third generation with attention to each component of the system to optimise performance and robustness, (4) integration into an ASV, (5) extensive sea testing (e.g. on the "MASSMO" exercises, experimental missions of autonomous marine vehicles conducted regularly around UK waters, and on research cruises.

人类排放的二氧化碳（主要来自化石燃料燃烧）在可预见的未来将继续成为气候变化的最重要原因。然而，我们的排放量中只有大约一半留在大气中。据信，另一半被陆地植被吸收和海洋吸收，数量大致相等。因此，这些二氧化碳的“自然汇”对我们具有巨大的价值，因为它们减缓了气候变化的进程，因此它们目前的运作以及未来对二氧化碳的吸收可能发生的变化是深入研究的焦点。如今，通过测量大气和海面 pCO2（海洋表面二氧化碳分压）来观察二氧化碳沉入海洋的情况。它控制着海洋和大气之间二氧化碳交换的速率，因此被全球海洋观测系统指定为“基本海洋变量”。这些观测通常是由商船进行的，在航线繁忙的地方，例如在大西洋和北太平洋的大部分地区，有足够的观测来描述海气通量。然而，在其他非常大的区域（例如印度、南太平洋和南大洋），我们的数据严重不足。未来，这种需求可以通过进行 pCO2 测量的自动地面车辆 (ASV) 来满足，我们的建议是开发专门为 ASV 设计的 pCO2 传感器。它将遵循国际机构制定的最高质量测量协议，这些协议适用于计算公海二氧化碳的海气通量。技术挑战是适应安装在船舶或大型浮标上的仪器的成功原理（空间和功率不是限制因素），以小空间和功率占用、抗剧烈运动和长续航时间实现相同的高精度，对于 ASV 来说是必需的。我们将通过汇集埃克塞特大学集团 20 多年来在操作船基二氧化碳系统方面的丰富经验，并利用 NOC 技术和工程团队的经验和专业知识，改进工程，来实现这一目标。我们将使用已在大型仪器上经过充分测试的基本测量技术（水与气体的平衡，以及通过非色散红外检测测量气体中的二氧化碳）。然而，我们将使用具有小体积和低气体流速的小型化组件，使得即使是小型仪器也能够携带机载校准气体。最终仪器的规格将包括：长达一年的耐用性和足以定义每日周期的测量频率（地表水和大气）、使用存储在微型压缩气瓶中的机载校准气体进行定期校准以及测量通过直接接触与地表水达到平衡的干燥空气中的二氧化碳。该仪器还将符合数据标准和集成协议，以便能够将传感器随时集成和交换到自主平台中。现有一个由 U. Exeter 建造的实验室原型。为了实现我们的主要目标，我们的子目标是： 1) 开发第二代并与船载仪器一起部署并在沿海站点进行测试 (2) 长期修改和部署在西部海峡天文台的系泊装置上 (3)构建第三代系统，注重系统的每个组件，以优化性能和稳健性，(4) 集成到 ASV 中，(5) 广泛的海上测试（例如，在“MASSMO”演习中，定期进行自主海洋车辆的实验任务英国水域和研究巡航。

项目成果

Tidal mixing of estuarine and coastal waters in the Western English Channel controls spatial and temporal variability in seawater CO2

西英吉利海峡河口和沿海水域的潮汐混合控制海水二氧化碳的时空变化

• DOI: 10.5194/bg-2021-166
• 发表时间: 2021-07-01
• 期刊: Biogeosciences Discussions
• 作者: R. Sims;M. Bedington;U. Schuster;A. Watson;V. Kitidis;R. Torres;H. Findlay;J. Fishwick;I. Brown;T. Bell
• 通讯作者: T. Bell