Understanding Formaldehyde and Glyoxal for New Satellite Measurements

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Man-made emissions of organic compounds such as toluene and ethene contribute to poor air quality and climate change. Currently there is a lot of interest in air quality issues focusing on the significant health and economic impacts of air pollution. In order to formulate, monitor and evaluate control measures it is vital that we are able to monitor the amount, composition and spatial distribution of anthropogenic emissions.Satellite measurements have already provided important data relevant for air quality issues, for example pictures of the distribution of NO2 emissions relevant for air quality. Satellites provide large scale pictures of emissions and the movement and development of airmasses, for example an airmass from an emissions source (e.g. an industrial area, or biogenic sources) being advected over rural areas. However, satellites cannot see the primary organic emissions discussed above, but they can see two of their oxidation products: glyoxal and formaldehyde. The ratio of glyoxal to formaldehyde (RGF) varies with different types of hydrocarbons e.g. biogenic vs anthropogenic emissions and also different types of anthropogenic emissions (e.g. toluene and ethene are predicted to have different RGF) although there is a lack of direct measurements of RGF for important anthropogenic emissions. Satellite measurements of RGF can therefore provide information on the nature of the emissions and can be used to verify emission inventories.The driver for this proposal comes from recent and planned launches of satellites that will significantly improve measurements of glyoxal, formaldehyde and NO2. In 2017 the Sentinel 5P satellite was launched which will provide a step change in spatial resolution (allowing identifications of pollution hot-spots within large conurbations). This will be followed in 2021 by Sentinel 4 which will be launched into a geostationary orbit observing Europe and providing both high spatial and temporal measurements of RGF. These data can only be fully utilized if the yield of formaldehyde and glyoxal from important anthropogenic emissions such as ethene and aromatic compounds is known accurately.UNFOGS will develop and characterise spectroscopic measurement techniques of formaldehyde and glyoxal and develop a new UK capability for detection of methylglyoxal, a closely related compound to glyoxal which may be monitored in future satellite campaigns. An atmospheric simulation chamber will be used to study the oxidation of key anthropogenic glyoxal and methylglyoxal forming compounds such as toluene, benzene, ethene and glycolaldehyde. The chamber measurements measure overall processes which are a combination of several elementary reactions. The chamber measurements will be supported, where appropriate, by complementary direct studies of key elementary reactions.An important component of UNFOGS is to work with our partners, who are working on satellite measurements, to develop appropriate models to interpret satellite measurements so that the full potential of these new instruments and measurements can be utilized to benefit air quality studies, an understanding of emissions, and links to health.