Development of a UAV-mounted Imaging FTIR for real-time monitoring of natural and anthropogenic hazards

自然灾害的特点是受影响的面积大，影响的规模和程度迅速变化，受灾地区的交通和通讯严重中断。在自然灾害发生期间和之后，对灾害影响的范围和严重程度进行准确和立即的评估，对于协助部署紧急服务和执行有效的减灾战略至关重要。人为危害评估要求的不同之处在于，设施的位置和空间范围是已知的，通常是相对有限的。因此，监测的要求是对通常高度复杂的基础设施进行长时间的高空间和时间分辨率监测，这些基础设施通常可以升高到离地面几十米的高度。获取具有基本二维和三维空间和时间分辨率和探测灵敏度的采样数据集，以满足应急服务、监管机构和商业用户的要求，是一项重大的监测挑战，也是一项关键的市场需求。各种各样的研究人员、利益团体、商业、应急和监管组织需要在从点源到景观尺度的空间尺度上对地表气体释放进行检测、量化和区分。查明烃类气体逸散性释放的来源和通量是若干应急和商业监测战略的关键组成部分。生物气几乎完全由甲烷组成，而热源（天然）碳氢化合物气则由甲烷、丙烷、丁烷和乙烷的混合物组成。垃圾填埋场的气体排放是地方议会和环境机构面临的一个常见环境问题，而管道的逸散排放对许多商业组织（从国内供应到大型石化设施）来说，是一个非常昂贵和不便的问题。目前应对这些挑战的方法仍然主要是基于地面和手动的。虽然地面方法在当地非常有效，但观测范围的限制往往会导致对危害的性质和程度了解不足，从而导致遏制和应对战略的效果较差，产生更严重和更持久的影响。基于遥感的方法已经使用了一系列传感器和平台，但是它们的操作效用受到严重限制，因为它们不能以必要的超高空间分辨率实时获得危害监测所需的最重要的物理参数（表面温度，特别是气体种类的识别和量化）。目前迫切需要开发一种低成本、坚固耐用、低质量的成像系统，该系统可以安装在无人机上，具有检测和区分逸散气体逸出的能力，并能准确地分辨表面温度。现有的基于成像的气体监测仪器无法以足够的精度分辨碳氢化合物气体。成像傅里叶变换干涉仪（FTIRs）具有检测和量化碳氢化合物排放的潜力，但目前的成像FTIRs设计功耗非常高，重量非常重，对于无人机的操作部署来说价格过高。该项目的目的是开发和验证一种低成本、轻质、紧凑的成像傅里叶变换红外（FTIR）光谱仪，该光谱仪可以安装在具有足够光谱分辨率和辐射灵敏度的无人机上，以检测和量化逸散性气体逸出。提取光谱发射率和表面温度测量的能力将使表面温度能够更准确地解决，发射光谱图像将使人类的存在和基础设施的识别更准确。

Natural hazards are characterised by the large area affected, rapidly changing scale and extent of the effects, and severe disruption to access and communication to the affected areas. During and after the onset of a natural disaster an accurate and immediate assessment of the extent and severity of the effects of the event is critical in order to assist the deployment of emergency services and to implement an effective mitigation strategy. The assessment requirement for anthropogenic hazards differs in that the location and spatial extent of the facility is known and is usually relatively restricted. The requirement for monitoring is therefore for high spatial and temporal resolution monitoring over extended periods over often highly complex infrastructure which can often be elevated 10s of metres off the ground. Acquisition of sampling datasets with the essential 2 and 3D spatial and temporal resolution and detection sensitivity to address the requirements of the emergency services, regulatory agencies and commercial users is a significant monitoring challenge and poses a critical market need. A diverse range of researchers, interest groups, commercial and emergency and regulatory organisations require the detection, quantification and differentiation of surface gas releases at spatial scales ranging from point source to landscape scale. Identification of the sources and fluxes of fugitive releases of hydrocarbon gas is a critical component of a number of emergency and commercial monitoring strategies. Biogenic gas is composed almost entirely of methane whereas thermogenic (natural) hydrocarbon gas is composed of a mixture of methane, propane, butane and ethane. Gas emissions from landfill sites are a common environmental issue faced by councils and the environment agency while fugitive emissions from pipelines are a very expensive and inconvenient problem for many commercial organisations ranging from domestic supply to large-scale petro-chemical facilities.Current methods to meet these challenges are still largely ground-based and manual. While ground-based methods are locally highly effective the limitation in the coverage of observations can often result in a poor understanding of the nature and extent of the hazard resulting in less effective containment and response strategies producing more severe and longer lasting effects. Remote-sensed based approaches have been implemented using a range of sensors and platforms however their operational utility has been severely limited as they cannot derive the most important physical parameters required for hazard monitoring (surface temperature and especially gas species identification and quantification) at the necessary ultra-high spatial resolution in real-time.There is an urgent need for the development of a low-cost, rugged, low mass, imaging system that can be mounted on a UAV that has the capability to detect and differentiate fugitive gas escapes and resolve surface temperature accurately. Currently available imaging based gas monitoring instruments are not capable of resolving the hydrocarbon gases with sufficient accuracy. Imaging Fourier Transform Interferometers (FTIRs) have the potential to detect and quantify hydrocarbon emissions but the current design of imaging FTIRs have a very high power consumption, are very heavy and are prohibitively expensive for operational deployment on a UAV. The aim of this project is to develop, and validate a low cost, lightweight, compact imaging Fourier Transform InfraRed (FTIR) spectrometer that can be operational mounted on a UAV that has sufficient spectral resolution and radiometric sensitivity to detect and quantify fugitive gas escapes. The ability to extract the spectral emissivity and surface temperature measurements will enable the surface temperature to be resolved much more accurately and emission spectra images will enable the presence of humans and identification of infrastructure more accurately .