Autonomous Ocean Carbon Observer Development and Calibration

快速动态的海洋生物碳泵（OBCP）在全球碳循环和大气二氧化碳浓度设定中发挥着重要作用。为OCBP提供燃料的光合生物以周为单位生存和死亡，由此导致的表层有机和无机碳颗粒的下沉（或输出）以及这些颗粒在更深水域的消耗损失也同样是变化的。简单地说，由于依赖于短期、季节性和空间有限的船舶观测，对OCBP的理解很差；因此，模型对其强度和未来轨迹的估计高度不确定。为了解决这一问题，研究人员将设计和海上测试两个机器人拉格朗日海洋碳观察者（OCO）浮标，能够执行8个月到多年的任务，同时能够在海洋的任何地方操作时，以小时到每天的时间尺度解决通量过程，并通过卫星遥测实时中继数据。OCO的发展能够识别颗粒有机碳和无机碳（POC和PIC）从表层海洋到地下水垂直转移的特定途径和控制。从逻辑上说，该项目是在研究人员开发和成功部署机器人拉格朗日碳探测器（CE）和碳通量探测器（CFE）浮子之后进行的，它们可以光学测量POC和PIC浓度以及1000米深度的通量变化。CFE的一个独特能力是它能够测量不同大小和类别的颗粒所携带的碳的沉降通量。该项目将合并CFE和CE能力来创建OCO。该团队将通过让加州大学伯克利分校的本科生和一名研究生参与项目的各个阶段（开发、实验室、航海和解释）和课堂，为STEM劳动力的发展做出贡献。具体来说，CFEs和两个新的海洋碳观测站（oco）将同时测量颗粒通量和浓度分布，并于2023年1月在海上进行测试部署。在这些自主仪器在目标深度上漂移的过程中（被传输到地面进行定位和实时双向遥测所中断），它们将自动量化捕获的下沉物质的固有光学特性和尺寸分布。Bishop等人（2016;Biogeosciences 13, 3019-3129, doi:10.5194/ kg -13-3109）描述了CFE的能力和方法，用于将原始OSR图像渲染为严格定义的粒子负载固有光学测量-衰减和交叉极化光子产率。Bourne等人（2019;Biogeosciences, 16, 1249-1264; doi:10.5194/bg-16-1249-2019）表明，在广泛的颗粒通量和粒径分布范围内，衰减与配备采样器的CFEs“（CFE-Cal浮标）”在150 m处采样的POC和PN密切相关（r^2 0.86）。计划进一步部署CFE-Cal浮标，对至少500米深度的下沉材料进行取样，这将使我们对衰减代理的校准得到验证，并使PIC光通量代理的首次校准成为可能。Bourne等人（2021;Biogeosciences, 18, 3053-3086, doi:10.5194/bg-18-3053-2021）证明了CFEs在解析和量化中层不同粒径类别携带的垂直通量方面的独特能力；此外，他们还描述了将在CFEs上实时分析通量大小分布的原型算法。该项目将使CFE和OCO系统能够在全球海洋中实现完全自主的长期部署。商业浮筒供应商（MRV Systems）和传感器制造商（Seabird Scientific）的参与可能会导致OCO的商业化途径。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The very fast and dynamic ocean biological carbon pump (OBCP) plays a fundamental role in the global carbon cycle and in setting concentrations of atmospheric carbon dioxide. Photosynthetic organisms that that fuel the OCBP live and die on a week to week basis, and the resulting sinking (or export) of organic and inorganic carbon particles from the surface layer and consumption losses of these particles in deeper waters are similarly variable. Simply stated, the OCBP is poorly understood due to dependence on short- term, and seasonally and spatially limited ship observations; thus model estimates of its strength and future trajectory are highly uncertain. To address this gap, the investigators will engineer and sea-test two robotic Lagrangian Ocean Carbon Observer (OCO) floats capable of 8 month to multi-year missions, yet able to resolve flux processes on hourly to daily time scales and relay data in real time via satellite telemetry while operating anywhere in the ocean. The development of the OCO enables the identification of specific pathways and controls on the vertical transfer of particulate organic and inorganic carbon (POC and PIC) from the surface ocean to subsurface waters. The project logically follows on from the investigator’s development and successful deployment of robotic Lagrangian Carbon Explorer (CE) and Carbon Flux Explorer (CFE) floats, which measure optically POC and PIC concentration and flux variability to depths of 1000 m. A unique capability of the CFE is that it is able to measure the sinking flux of carbon carried by different sizes and classes of particles. The project will merge CFE and CE capabilities to create the OCO. The team will contribute to the development of a STEM workforce by engaging UC Berkeley undergraduates and one graduate student in all phases (development, laboratory, seagoing, and interpretive) of the project and in the class room. Specifically, CFEs and two new Ocean Carbon Observers (OCOs) that simultaneously measure both particle flux and concentration profiles will be constructed and test-deployed at sea in January 2023. During the times that these autonomous instruments drift at target depths within the upper kilometer (interrupted by transit to the surface for location and real time bidirectional telemetry), they will autonomously quantify the inherent optical properties and size distributions of sinking material captured. Bishop et al. (2016; Biogeosciences 13, 3019-3129, doi:10.5194/bg-13-3109) describe CFE capabilities and methodology for rendering raw OSR imagery to rigorously defined inherent optical measures of particle loading -- attenuance and cross-polarized photon yield. Bourne et al. (2019; Biogeosciences, 16, 1249-1264; doi:10.5194/bg-16-1249-2019) show that attenuance is strongly correlated (r^2 0.86) with POC and PN sampled at 150 m by sampler-equipped CFEs “(CFE-Cal floats)” over a broad range of particle flux and particle size distributions. Planned further deployment of the CFE-Cal floats to sample sinking material to depths of at least 500 m will enable validation of our calibration of the attenuance proxy and to enable a first calibration of the PIC optical flux proxy. Bourne et al. (2021; Biogeosciences, 18, 3053–3086, doi:10.5194/bg-18-3053-2021) demonstrate the unique capability of CFEs to resolve and quantify the vertical flux carried by different particle size classes in the mesopelagic; furthermore, they describe prototype algorithms that will lead to flux size-distribution analysis in real time on the CFEs. The project will enable fully autonomous long-term deployments of CFE and OCO systems in the global ocean. The involvement a commercial float vendor (MRV Systems) and sensor manufacturer (Seabird Scientific) may lead to a commercialization pathway for the OCO.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.