The Big Interview
Dr Ben Veihelmann, European Space Agency Air Quality News talks to Ben Veihelmann, atmospheric scientist at the European Space Agency (ESA).
Ben Veilhelmann is a lead scientist at ESA supporting the development of the Copernicus satellite missions Sentinel-4 and Sentinel-5. Copernicus is the European’s Earth Observation programme, which looks at our planet in order to provide information services on a range of themes, including ocean, land, climate and atmosphere. The Sentinel-5 Precursor is the first Copernicus satellite dedicated to providing atmospheric composition observations and is a collaborative project between the ESA and the Netherlands Space Office, costing around €220m from design to launch. ‘Such satellite missions are usually set up in a multinational context,’ says Ben, ‘it is much more efficient to join forces.’ On board the Sentinel-5 Precursor satellite is the Tropospheric Monitoring Instrument known as TROPOMI. This instrument looks specifically at the troposphere, the part of the atmosphere that is directly relevant to the air we breathe. The TROPOMI instrument launched in 2017 and has since orbited the Earth 20,000 times, travelling at a speed of 7.5 kilometres per second, and observing the composition of our atmosphere with daily global coverage. ‘My role is to overlook the development process of such satellites and run the necessary scientific developments,’ says Ben. The TROPOMI instrument measures, amongst others, nitrogen dioxide, ozone, methane, and carbon monoxide. This data allows scientists to assess trends and spatial patterns in air pollution on a local and global scale. ‘While the emissions of air pollution can be local, the 26
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pollutants can travel quite far, this means that air pollution is by no means a local problem. ‘Air pollution crosses borders at will. If you look at pollution levels on a country scale, the question that immediately pops up is, which part of the pollution is our responsibility and which part is the responsibility of someone else? ‘The satellites cover entire continents and give us a synoptic view; they can capture events that are simply not captured by local monitoring stations.’ Using satellite data to look at global air pollution patterns has never been more important. Over the past two years, international lockdowns and massive wildfires globally have caused significant volatility in air quality.
"If you look at pollution levels on a country scale, the question that immediately pops up is, which part of the pollution is our responsibility and which part is the responsibility of someone else?" ‘The Covid-19 pandemic was inadvertently an Earth system experiment,’ says Ben. ‘If I asked the entire global industry to switch off their engines for a month for the sake of studying the Earth system, they would never agree. But this is exactly what happened. ‘This data is helping us to improve our quantitative understanding of the link between emissions and pollution levels. ‘The European Union recognises that air pollution is a
