Airborne Mapping Of The 3-Dimensional Structure Of Urban Boundary Layers

The burden of poor air quality is a major public health issue, reducing life expectancy by contributing to the development of a number of diseases, and as such results in costs to the economy, healthcare and reduces quality of life. There remains vast uncertainties in Earth systems models, partly because of insufficient observation data. Ground-based observation networks are sparse, and satellite data has insufficient spatial resolution to represent intra-urban variability. Insufficient measurement of a problem inevitably leads to improper management. Nitrogen dioxide (NO2) is an air pollutant dominantly sourced from fuel combustion (e.g. road transport) and often reaches deleterious concentrations in cities across the world. This thesis represents the scientific progress and status of the Compact Air Quality Spectrometer (CompAQS) concept. The CompAQS concept seeks to produce tropospheric NO2 column densities at 1x1 km ground resolution for urban areas from a low-Earth orbit satellite platform. Successful airborne demonstrations with a breadboard level model (Airborne Nitrogen Dioxide Imager) allowed the concept to be further progressed with a new instrument build CompAQS Space Technology (CompAQS-ST). CompAQS-ST was the culmination of lessons learnt and foresight of the potential future opportunities the CompAQS concept could bring. CompAQS-ST was built and optically aligned at the University of Leicester, providing the opportunity for the performance to be thoroughly tested to ensure the scientific objectives would be met. Flight plans were developed for an aerial survey to best demonstrate the surge in performance gained by the CompAQS-ST spectrometer. The CompAQS-ST airborne demonstration took place in February 2018, successfully retrieving tropospheric NO2 over cities and rural areas. The unique dataset achieved a ground resolution of 70x70 m2, provided insight in to the high levels of variability in NO2 concentrations down to street level, and highlighted the effects of meteorology on the distribution of NO2 for a snapshot in time.