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: 2048509
• 负责人: Brendan Carter
• 金额: $ 10.97万
• 依托单位: University of Washington
• 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 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048509&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可居住性至关重要。海洋碳汇的规模仍然很大，主要是因为船只对地表水二氧化碳（pCO 2）的测量很少。配置浮标配备用于生物化学（BGC）测量的传感器，如pH值-可用于估计pCO 2-有可能大大提高世界海洋表面二氧化碳观测量，特别是在船上测量很少的地区和时间。全球部署的BGC浮标数量预计将在未来几年通过全球海洋生物地球化学阵列（GO-BGC）和南大洋碳和气候观测与建模计划（SOCCOM 2）等计划迅速增加。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善我们对海洋每年吸收多少人为碳的估计之前，仍然有一些根本性的问题需要解决。该项目的首要目标是提高从分析浮子数据得出的pCO 2估计值的准确性和精度。该项目将支持一名博士后研究员和三名本科生暑期实习生。该项目旨在通过解决可能导致这些计算中的系统性偏差的突出问题和问题，提高与基于浮动的pCO 2估计相关的准确性和不确定性。具体来说，研究人员的目标是回答以下问题：1）是什么原因导致瓶和浮子pH值之间的压力依赖性差异？2)热力学海洋无机碳模型的内部不一致性的来源是什么，它影响了pH测量计算pCO 2的准确性？3)全球1500米处酸化率的时空模式是什么？我们如何准确地模拟这些模式？该团队将进行一系列实验室研究，以量化关键热力学常数，测试有机化合物是内部不一致性的重要贡献者的假设，并确定一个强大的协议来根据pH值准确计算pCO 2。此外，一个开源的全球算法将可用于准确预测特定区域的人为碳估计，这对于全局地精确校正浮子pH传感器漂移是必要的。最后，为了评估基于这些努力的基于浮子的pCO 2估计的准确性的提高，该团队将使用Spray水下滑翔机和Wave Glider进行一系列现场验证实验，Spray水下滑翔机配备了与剖面浮子相同的pH传感器，Wave Glider是一种自主水面车辆，配备了用气体标准校准的pCO 2分析仪，精度为正负两个微气压。 在整个项目过程中，该团队将测试16种不同的pH传感器，以更好地限制基于pCO 2估计值的潜在系统偏差。这里概述的活动将导致更准确的估计pCO 2从浮标，以及更好的约束不确定性，并最终导致更好的估计气-海CO2通量从全球网络的BGC profiling floats.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

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
• 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