Countries that have closed their doors to slow the spread Coronavirus pandemic, satellites orbiting Earth notice changes in our home world.
Specifically, the orbiting instruments observe reductions in emissions and nighttime lighting when people follow orders to stay at home and reduce contact with others. Such approaches are essential to slow the person-to-person passage of the new coronavirus that causes COVID-19 disease. However, these measures also reduce the visibility of humanity on Earth.
Because the new coronavirus has spread so quickly, satellites are monitoring its impact on several continents at once. Take, for example, Wuhan, China, where the pandemic started with the new year. The first reported death from the disease occurred in mid-January; the quarantine was decreed on the city later this month.
Satellite images of the region taken at night in mid-January and early February show the effects of this quarantine. In particular, these images show reduced night lighting on the roads because the transport of people and goods has decreased considerably with quarantine. (To better see the differences between the two images, make sure your screen is set to a high brightness level.)
“The lights offer a different perspective on human settlements”, Miguel Román, principal investigator of the “Black Marble” research team which directs this work, said in a NASA statement. “We are not just looking at where the roads are; these images tell us when and if the roads are being used. We are looking at human activities.”
China’s quarantine measures have also led to changes in the atmosphere’s skies, according to satellite observations. Carbon monoxide levels in the troposphere above Wuhan and Beijing have dropped by about 10% since the implementation of the quarantine measures, according to a recent set of measures.
And, after all, the roads are the same; it is human activities that evolve thanks to these public health measures. Similarly, in Europe and the United States, satellites monitor emissions change, in particular nitrogen dioxide emissions.
A satellite particularly well suited to these observations is a mission of the European Space Agency called Copernicus Sentinel-5P, which collects data on emissions of nitrogen dioxide and other key compounds that affect climate and human health. Although the levels of this gas in the atmosphere change over time, average measurements over a week or two remove these effects, giving scientists an accurate picture of how emissions are changing.
Nitrogen dioxide emissions in France compared to a 10-day period this month and the monthly average for March 2019.
Nitrogen dioxide emissions in Italy compared to a 10-day period this month and the monthly average for March 2019.
“The special characteristics of the Copernicus Sentinel-5P satellite, with its high spatial resolution and its precise ability to observe traces of gas compared to other atmospheric satellite missions, allow the generation of these unique measurements of nitrogen dioxide concentration from space “, Claus Zehner, ESA’s Copernicus Sentinel-5P chief of mission, said in a statement.
Although ESA focuses on the data that this spacecraft has collected from its European member countries, the satellite is also studying the United States and the rest of the world, and that data is publicly available.