Satellites placed on Earth’s orbit show not only what is happening on the planet. Also, they tell about pollution in the atmosphere.
Harmful substances from cars and trucks, the burning of fuels in power plants or activities of industry, they are all visible on satellite imagery. Eventually, it turns out that reducing human activity associated with the coronavirus epidemic gives us better air quality. As the virus epidemic progressed, governments took unprecedented measures to restrict the movement of people. First in China and then in Europe. In many places, it stopped industry, freight transport and most of the services. Satellite images show how this affects the atmosphere.
The analysis was based on satellite images from Sentinel-5P, available on the CREODIAS platform. Recent Sentinel-5P satellite pictures document the emission of NO2, among other things. This is possible thanks to the installed Tropomi instrument. The maps show weekly average values of NO2 column density measures between mid-February to mid-March 2020. As far as measurements concerning Europe are concerned, we observe a remarkable reduction of NO2 emissions in northern Italy. This is at a time when Italy normally deals with winter smog, so explains Sybrand van Beijma. He is an earth observation data specialist from CloudFerro, the operator of the CREODIAS platform.
The CREODIAS platform provides satellite images from Earth observation for the European Space ESA). On this cloud platform you can search, view and process huge collections of historical and real-time satellite images. CloudFerro is the provider of these cloud services. They build and operate cloud computing platforms for specialized markets, such as the European space sector. Their experience and expertise include storing and processing big data sets, such as multipetabyte repositories of Earth Observation satellite data.
Closed cities in China
Chinese authorities introduced its restrictions earlier than European countries. We can see the effects on the pictures from Sentinel-5P: – If we compare the pictures from the last few weeks and later, we see significant changes in air quality in China. In a picture taken near New Year’s Eve, we see a normal, standard NO2 level. In early February, when some Chinese cities were actually cut off from the world. Industry stopped. That’s why we can see a sharp decrease in emissions with the clearest air. After that, when part of the industry is slowly coming back to normal, we see an increase in emissions again. But… not to the levels before the virus epidemic – explains CloudFerro expert Van Beijma. In short, both situations show that the preventive measures taken by individual countries, with reduce transport and production, have a significant impact on reducing air pollution.