INSUBCONTINENT EXCLUSIVE:
Image caption
Shipping lane: The Tropomi instrument detects a suite of gases including nitrogen dioxide
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 NO?." Media captionPepijn Veefkind: Tropomi data will be important for future
emissions regulationNitrogen 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
NO? 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." Analysis by David Shukman, BBC Science EditorFar
beyond the horizon, steaming through the remote High Seas, the great fleets of global shipping have for years been too distant to be
Only in port can anyone catch sight of the plumes of dark smoke rising from the vessels' engines
But added together, the greenhouse gases from the world's 50,000 ships make this industry the world's sixth largest emitter, and most of it
This has long fuelled suspicions among environmental campaigners
Exempt from the Kyoto Protocol and then the Paris Agreement, shipping acquired a reputation as a sector that dodged its responsibilities on
That's why the landmark deal earlier this month for a cut in emissions of 50% by 2050 received so much attention
But it also raised a host of questions about policing: who would keep watch, and how Europe's Sentinel programme is part of the answer
Suddenly, at just the right time, the world's shipping lanes are in full view.Image copyrightGetty ImagesImage caption
The shipping sector has made a commitment to reduce emissions
S5P's availability is timely
The shipping sector has just signalled its intention to make big reductions in its emissions over the next 30 years, in particular of the
greenhouse gas carbon dioxide
At the moment, those emissions are calculated in a "bottom-up" fashion
By knowing the size of the global fleet, where it moves, the ships' specifications and how much fuel they are likely consuming - it is
possible to estimate how much CO?, or indeed NO?, is being pumped into the atmosphere from exhausts.But this all involves quite a few
assumptions, and so the models need to be audited by some top-down analysis as well - which is where satellites come in.S5P-Tropomi does not
see CO?, although its NO? observations can act as a tracer in the sense that wherever nitrogen dioxide turns up on shipping lanes, there
But the best solution would be a dedicated carbon-monitoring satellite
This is why the EU has asked its technical agent on space matters, the European Space Agency, to design a Sentinel specific to the task
Dubbed Sentinel 7 by many people, because that is the next available number in the series, this future mission should fly in the 2020s
The aim is to be able track CO? down through the atmosphere on a scale of around 3km by 3km, but over a wide area
That would make Sentinel 7 a forceful partner for Sentinel 5.Image copyrightECMWF/CAMSImage caption
"Bottom up"
accounting: Estimate of CO2 emissions from ships in 2016
Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos
