|Paper title||One year of greenhouse gas column concentrations from the London Carbon Emissions Experiment|
|Form of presentation||Poster|
Carbon emissions related to fossil fuel tend to come from localised sources, with urban areas in particular contributing more than 70% of global emissions. In the future, the proportion of the world's population living in cities is expected to continue to rise, resulting in a shift towards an even greater contribution towards fossil fuel related emissions originating from urban areas. Cities are also the focal point of many political decisions on mitigation and stabilisation of carbon emissions, often setting more ambitious targets than national governments (e.g. through the C40 group of cities around the world). For example, the Mayor of London has set the ambitious target for London to be a zero carbon city by 2050. If we want to devise robust, well informed climate change mitigation policies, we need a much better understanding of the carbon budget for cities and the nature of the diverse emission sources within them, underpinned by new approaches that allow verification and optimisation of city carbon emissions and their trends. New satellite observations of CO2 from missions such as OCO-3, MicroCarb and CO2M, especially when used in conjunction with ground-based sensor networks, provide a powerful and novel capability for evaluating and eventually improving existing CO2 emission inventories.
In April 2021 we set up a ground-based measurement network comprising three sites, located upwind, downwind and in the centre of London, using portable greenhouse gas (CO2, CH4, CO) column sensors (Bruker EM27/SUN spectrometers) together with UV/VIS MAX-DOAS spectrometers (NO2). The instruments have so far operated continuously over the course of one year, which we have achieved by automating the sensors and housing them inside weatherproof enclosures. The data we have acquired from the network will not only allow us to critically assess the quality of satellite observations over urban environments, but also to derive data-driven emission estimates using a measurement-modelling framework. Here we will show and discuss findings from our first year of greenhouse gas column observations over London.