Monitoring smog together in Beijing

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From space you have a good view of what’s happening on the ground, and satellite monitoring of terrestrial processes using optical technology is on the rise. For instance, the Chinese space institute BISME and TNO are working together to measure and improve air quality in Beijing.

“New applications for optical monitoring from space are appearing all the time,” says Bart Snijders, Business Consultant at TNO. Optical instruments can be used to monitor air quality, but also water quality. “For instance, you can now follow the course of a disaster from space, see where the most damage has been done, and know where help should be sent first.” Another application is the monitoring of agricultural properties, which allows farmers to see – from a height of 700 kilometres, and with an accuracy of five square metres – whether and where their land needs water or fertilizer. Services like Google Earth also use satellites to keep their information up to date.

“You can now follow the course of a disaster from space, see where the most damage has been done, and know where help should be sent first”

Collaboration with China

The number of possible applications is growing, and so is interest in these innovative technologies. Snijders: “Including in China, which is hard at work catching up on space technology.” The Beijing Institute of Space Mechanics and Electricity (BISME) and TNO have entered into a partnership to exchange knowledge and start projects. Snijders is one of the pioneers in this collaboration: “We started by developing instruments to monitor air quality in Beijing. And for good reason: there are still no reliable data, but the city’s smog can shorten its residents’ lives by years.”

Monitoring smog from space

Measures clearly needed to be taken. “To get started on that, you have to know what the sources of air pollution are, and how smog spreads,” explains Snijders. “We measure that from space. Our optical equipment analyses the sunlight reflected from the Earth’s surface, and then determines – by looking at the absorption of different wavelengths – what materials are present and in what concentrations.” That sounds easier than it is. “When you’re doing these measurements from a height of hundreds of kilometres, you’re measuring the concentration of a substance not just on the surface of the Earth but in the entire air column below the satellite. So if you want to know how bad the smog in a given Beijing district is, you have to process the measurement data. Our TNO colleagues and the KNMI scientists are expert at this, and are closely involved in our collaboration with BISME. And in order to also be able to predict changes in this air quality, we developed a model that takes the weather forecast and pollution sources into consideration. We are currently working hard on its improvement.”


The air quality (nitrogen dioxide concentration) in Asia as registered on 10 October 2017. The dark warm colours represent the poor air quality above Seoul and Beijing.

Improving air quality

The Chinese authorities have been taking measures based on this kind of knowledge, and Beijing air quality is gradually improving. In the meantime BISME and TNO have already launched other projects. Snijders: “Monitoring the emission of the greenhouse gas CO2, for instance, which is something the Chinese government wants a clearer picture of. There’s more in the pipeline, but I can’t talk about it yet. It shows, at any rate, that the contacts are good. To strengthen ties still further, from 16 to 18 October 2017 a strong BISME delegation came to Delft for the 4th International Symposium of Space Optical Instrument and Application.”

“Until recently it was only big players like ESA and NASA who had orders; now that building and launching small satellites has become much cheaper and simpler, private companies – and even, ultimately, individuals – can be clients”

Giving Dutch businesses new opportunities

Expertise in the use of optics in space is not only applicable in China, Snijders adds: “We can make use of our Chinese experience elsewhere, too, including the Netherlands. So we’re going to be using our contacts to give Dutch businesses new opportunities. Those opportunities are growing all the time, because the space industry is changing fast. Until recently it was only big players, like ESA and NASA, who had orders. Now that building and launching small satellites – so-called ‘CubeSats’ – has become much cheaper and simpler, private companies – and even, ultimately, individuals – can be clients.” Little of this development has yet been seen in China. “There the government will be our biggest client for the time being, but things are moving fast”, says Snijders. “That’s why we have to stay on top here in the Netherlands. It’s like surfing: you have to stay near the top of the wave to keep moving.”

contact person
Ir. Bart Snijders Locatie Leiden - Sch + Page 1 Location: Location Delft - Stieltjesweg
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