Design and development of a compact Earth observation instrument for high resolution monitoring of atmospheric methane

Abstract

Methane is a potent greenhouse gas, with recent growth in atmospheric concentration potentially linked to human-driven emissions. Reducing these anthropogenic emissions is an effective and rapid mitigation strategy for rising surface temperature due to methane's atmospheric lifetime of around nine years. Point source emissions from the oil and gas industry constitute a large proportion of human methane emissions, representing a significant cost to the economy and the global environment.

Most existing satellite data lack the high spatial resolution required to identify these localised emissions, and ground based measurement approaches can be costly and ineffective. Improving the resolution of methane sensing from space will enable better detection, quantification, and ultimately repair of methane leaks.

This thesis describes the development of a new methane sensing instrument aimed at addressing this challenge. The first chapter provides an introduction to methane in Earth's atmosphere, including a review of the sources and sinks, both natural and anthropogenic. Methane's impact as a greenhouse gas is considered, as well as the key role played by fugitive emissions. The second chapter is a technology review: a range of instrument technologies and deployment platforms are considered in the context of the measurement needs, and a down-selection of three instrument technologies and one platform is made. The third chapter details computer modelling work comparing the various technology options. A radiative transfer model is used to simulate instrument observations, before selection of a single technology is made. Further modelling, including development of a full observation simulation, is employed to assess the expected performance of the chosen instrument technology basis. The fourth chapter describes laboratory activities performed to evaluate the core multispectral imaging concept selected. Varying methane levels were observed and the system performance measured. Some limitations of the current concept are highlighted and now form an area for further work. The fifth chapter looks ahead to future development activities, including a description of a proposed satellite mission, and a summary of activities already in progress geared towards this goal.