Collaborative Research: Improving the accuracy and uncertainty associated with estimated pCO2 from pH sensors on autonomous profiling platforms

协作研究：提高自主分析平台上 pH 传感器估计 pCO2 的准确性和不确定性

• 批准号: 2049117
• 负责人: Yuichiro Takeshita
• 金额: $ 79.39万
• 依托单位: Monterey Bay Aquarium Research Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2049117&HistoricalAwards=false
• 关键词: Collaborative; Research; Improving; accuracy; uncertainty

Understanding how much anthropogenic carbon dioxide the ocean is taking up from the atmosphere - and how this uptake changes over time - is critical for understanding the habitability of our planet. Uncertainties in the size of the ocean carbon sink remain large, mainly because of sparse measurements of surface water carbon dioxide (pCO2) measurements from ships. Profiling floats equipped with sensors for biogeochemical (BGC) measurements such as pH – which can be used to estimate pCO2 – have the potential to greatly improve the amount of surface carbon dioxide observations across the world’s ocean, particularly in regions and times of year where shipboard measurements are scarce. The number of BGC floats deployed worldwide is expected to rapidly increase in the coming years through programs like the Global Ocean Biogeochemistry Array (GO-BGC) and the Southern Ocean Carbon and Climate Observations and Modeling program (SOCCOM2). However, there are still fundamental issues that need to be resolved before we can take full advantage of this emerging, powerful global observational network to improve our estimates of how much anthropogenic carbon the ocean absorbs every year. The overarching aim of this project is to improve the accuracy and precision of pCO2 estimates that are derived from profiling float data. The project will support a postdoctoral researcher and three undergraduate summer interns.This project seeks to improve the accuracy and uncertainty associated with float-based estimates of pCO2 by addressing the outstanding questions and issues that could lead to systematic biases in these calculations. Specifically, the investigators aim to answer the following questions: 1) What causes the pressure-dependent discrepancy between bottle and float pH? 2) What is the source of the internal inconsistency of the thermodynamic marine inorganic carbon model, which affects the accuracy of pCO2 computed from pH measurements? 3) What are the global spatiotemporal patterns of acidification rate at 1500 m, and how do we model the patterns accurately? The team will conduct a series of laboratory studies to quantify key thermodynamic constants, test the hypothesis that organic compounds are a substantial contributor for the internal inconsistency, and determine a robust protocol to accurately calculate pCO2 from pH. Furthermore, an open-source, global algorithm will be made available that accurately predicts region-specific anthropogenic carbon estimates, which is necessary to accurately correct float pH sensor drift globally. Finally, to assess the improvement in accuracy of float based pCO2 estimates based on these efforts, the team will conduct a series of field validation experiments using Spray underwater gliders equipped with the same pH sensor as profiling floats, and a Wave Glider, an autonomous surface vehicle that is equipped with a pCO2 analyzer calibrated with gas standards with an accuracy of plus or minus two microatmospheres. Over the course of the project, the team will test 16 different pH sensors to better constrain the potential systematic biases for the float based pCO2 estimates. The activities outlined here will lead to more accurate estimates of pCO2 from floats, as well as better constrained uncertainties, and ultimately lead to better estimates for air-sea CO2 flux from the global network of BGC profiling floats.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.

了解海洋从大气中吸收了多少人为二氧化碳以及这种吸收如何随时间变化对于了解我们星球的宜居性至关重要，这主要是因为测量稀疏。配备用于生物地球化学 (BGC) 测量（例如 pH 值）的传感器的船舶地表水二氧化碳 (pCO2) 测量（可用于估计 pCO2）有可能大大提高整个地表二氧化碳的观测量。通过全球海洋生物地球化学阵列 (GO-BGC) 和南大洋碳等项目，全球部署的 BGC 浮标数量预计将在未来几年迅速增加。然而，在我们能够充分利用这个新兴的、强大的全球观测网络来改进我们对海洋中人为碳含量的估计之前，仍然有一些基本问题需要解决。该项目的总体目标是提高根据浮点数据分析得出的 pCO2 估算值的准确性和精确度。该项目将为一名博士后研究员和三名本科生暑期实习生提供支持。该项目旨在提高与浮点数据相关的准确性和不确定性。具体来说，研究人员旨在回答以下问题：1) 是什么导致了瓶子和浮子之间的压力依赖性差异。 pH 值？ 2) 热力学海洋无机碳模型的内部不一致会影响 pH 测量计算出的 pCO2 的准确性？ 3) 1500 m 处的全球酸化率时空模式是什么？准确地对模式进行建模？该团队将进行一系列实验室研究来量化关键的热力学常数，测试有机化合物是造成内部不一致的重要因素的假设，并确定一个可靠的方案来准确计算此外，还将提供一种开源的全球算法，可以准确预测特定区域的人为碳估算值，这对于在全球范围内准确校正浮子 pH 传感器漂移是必要的。基于这些工作的 pCO2 估计，该团队将使用配备有与剖面浮标相同的 pH 传感器的 Spray 水下滑翔机和 Wave Glider（一种配备有 pCO2 分析仪的自动水面飞行器）进行一系列现场验证实验。准确度为正负两个微大气的气体标准 在项目过程中，团队将测试 16 个不同的 pH 传感器，以更好地限制基于浮子的 pCO2 估算的潜在系统偏差。浮标的 pCO2 估算，以及更好的约束不确定性，最终导致 BGC 剖面浮标全球网络对海气二氧化碳通量的更好估算。该奖项反映了 NSF 的法定使命，并被认为是值得的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来获得支持。

项目成果

New and updated global empirical seawater property estimation routines

新的和更新的全球经验海水特性估计例程

• DOI: 10.1002/lom3.10461
• 发表时间: 2021-12
• 期刊: Limnology and Oceanography: Methods
• 作者: Carter, Brendan R.;Bittig, Henry C.;Fassbender, Andrea J.;Sharp, Jonathan D.;Takeshita, Yuichiro;Xu, Yuan‐Yuan;Álvarez, Marta;Wanninkhof, Rik;Feely, Richard A.;Barbero, Leticia
• 通讯作者: Barbero, Leticia