Sentinel tracks ships' dirty emissions from orbit

[Nergal]

 

The new EU satellite tasked with tracking dirty air has demonstrated how it will become a powerful tool to monitor emissions from shipping.

Sentinel-5P was launched in October last year and this week completed its in-orbit commissioning phase.

But already it is clear the satellite's data will be transformative.

This latest image reveals the trail of nitrogen dioxide left in the air as ships move in and out of the Mediterranean Sea.

The "highway" that the vessels use to navigate the Strait of Gibraltar is easily discerned by S5P's Tropomi instrument.

"You really see a straight line because all these ships follow approximately the same route," explained Pepijn Veefkind, Tropomi's principal investigator from the Dutch met office (KNMI).

"In this case, we also looked into how many big ships there are in the region [at the time], and there's really not that many - around 20 or so, we estimate - but each one is putting out a lot of NO₂."

Nitrogen dioxide is a product of the combustion of fuels, in this instance from the burning of marine diesel. But it is also possible to see in the picture the emissions hanging over major urban areas on land that come from cars, trucks and a number of industrial activities. NO₂ will be a major contributor to the poorer air quality people living in those areas experience.

Sentinel-5P is the next big step because of its greater sensitivity and sharper view of the atmosphere.

"Shipping lanes are something we've seen on previous missions but only after we've averaged a lot of data; so, over a month or a year. But with Tropomi we see these shipping lanes with a single image," Dr Veefkind told BBC News.

"The resolution we got from our previous instruments was about 20km by 20km. Now, we've gone down to 7km by 3.5km, and we are thinking of going to even smaller pixels."