UAS-Methane: An unmanned aerial system for the remote sensing of methane flux

这个概念验证项目的目标是开发和测试一个集成的新型无人机系统（UAS）遥感平台，用于测量三维甲烷浓度场和排放通量。我们的技术方法是将旋转悬停无人机与扫描开路可调谐二极管激光吸收光谱仪（TDLAS）集成在一起，并使用它快速检索局部尺度（1米至1公里）上随时间变化的甲烷羽流浓度场。三维羽流平流的实时测量和可视化将有助于热点排放通量的计算，并为气体泄漏应用提供服务——这是一个与NERC温室气体源分配科学相关的应用，具有广泛的可转移性，适用于一系列行业。我们迫切需要技术来应对这一科学和影响挑战。目前，国家人为甲烷清单和工业生命周期分析是对各种成分源类型外推的逸散排放的最佳猜测。甲烷的自然（生物源）来源也很难通过测量来描述。正如2015年在巴黎举行的第21届缔约方大会（cop21）上达成的协议，目前估计的人为甲烷库存现在必须包括测量验证，以实现和监测2050年雄心勃勃的排放目标。基于无人机的测量为实现这一目的提供了成熟的适当技术。UAS的垂直轮廓、机动性和观察几何形状为局部尺度遥感应用和现场监测提供了独特的采样。该提案旨在开发这种从概念到原型的能力，并建立在团队为其他环境科学应用开发无人机的经验基础上。英国在使用UAS技术进行环境科学方面的专业知识和基础设施落后于新兴的国际社会，后者承诺在几个NERC主题中彻底改变对当地规模过程的理解（见图1）。我们在开发和飞行现场UAS测量系统方面的经验，开发了一种新的遥感UAS TDLAS扫描技术。该项目开发了一个新的通量概念，并解决了传感器平台集成中的实际挑战。TDLAS与UAS的集成与TRL 3/4（非集成组件）相当，而我们试图使用的数据遥测和层析反演算法来从浓度测量中获得通量都是概念性的（与TRL 2相当）。我们将根据TRL 5/6标准（台架测试和验证）开发和测试这种集成技术，以便在项目结束时准备好一个工作原型平台进行现场试验。综上所述，我们的概念是在无人机平台上通过遥感检索甲烷通量。解决这一概念的技术是开发一个集成的带有扫描框架的UAS-TDLAS平台。验证这一概念所需的证据将是一个经过验证的数据集，该数据集使用定制的层析成像算法来反演甲烷通量的浓度测量值。

The goal of this proof of concept project is to develop and test an integrated new unmanned aerial system (UAS) remote sensing platform for the measurement of 3-dimensional methane concentration fields and emission flux. Our technology approach is to integrate a rotary-hovering UAS with a scanning open-path tuneable-diode-laser absorption spectrometer (TDLAS) and use it to rapidly retrieve time-evolving methane plume concentration fields over local scales (1m to 1 km). A real-time measurement and visualisation of 3D plume advection would facilitate the calculation of hotspot emission flux and serve gas-leak applications - an application relevant to NERC greenhouse-gas source apportionment science with transferability for a range of industries. There is an urgent technological need to meet this science and impact challenge. National anthropogenic methane inventories and industrial life cycle analyses are at present a best guess of fugitive emissions extrapolated for various component source-types. Natural (biogenic) sources of methane are also poorly characterised by measurement. As agreed at the 21st Conference of the Parties (COP-21) in Paris in 2015, currently estimated anthropogenic methane inventories must now include validation by measurement to meet and monitor ambitious 2050 emissions targets. UAS-based measurement offers an appropriate technology ripe for development for this purpose. The vertical profiling, manoeuvrability, and viewing geometry of UAS offers unique sampling for local-scale remote sensing applications and site-wide monitoring. This proposal seeks to develop such a capability from concept to prototype and builds on the team's experience in development of UAS for other environmental science applications.UK expertise and infrastructure in the use of UAS technology for environmental science lags behind an emerging international community that promises to revolutionize understanding of local scale processes across several NERC themes (see Figure 1). We build on our experience in developing and flying in situ UAS measurement systems to develop a new remote sensing UAS TDLAS scanning technology. The project develops a new flux concept and addresses practical challenges in sensor-platform integration. The integration of TDLAS with UAS is commensurate with TRL 3/4 (non-integrated components), while data telemetry and the tomographic inversion algorithms we seek to use to derive flux from concentration measurements are all conceptual (commensurate with TRL 2). We will develop and test this integrated technology to TRL 5/6 criteria (bench test and validation) such that a working prototype platform may be ready for field trial at the conclusion of the project. To summarise, our concept is to retrieve methane flux by remote sensing on a UAS platform. The technology to address this concept is the development an integrated UAS-TDLAS platform with a scanning gimbal. And the proof required to validate the concept will be a validated dataset, which uses tailored tomographic algorithms to invert concentration measurements for methane flux.