LA Carbon Spy Observatory. From space

Most people again forever attracted to sunny skies, nearby oceans, or mountains that embrace the Los Angeles Basin, environmental engineer Annmarie Eldering was drawn to the city’s smog. “It’s the best place,” he says. “You have a lot of pollution!”

Urban areas release more than 70% of the carbon dioxide emissions generated by humans into the atmosphere, and LA is no exception. It has a population of more than 13 million in its larger metropolis, a sophisticated highway network and an international transportation hub. LA produces the fifth CO₂ from all the cities of the world. This makes it a sweet place to study the role of humans in climate change.

Eldering is a scientist in NASA’s Orbiting Carbon Observatory-3 or OCO-3 project, an instrument that measures atmospheric CO.₂ to better understand the impact of human activity on the natural carbon cycle of levels from space, the process by which plants, soils, oceans, and atmospheres exchange carbon with each other. In one paper published this month, Eldering and his colleagues have released a map showing the most accurate variations of CO₂ emissions from the LA basin that have never been seen from space. This research has shown that space-based monitors can be used to collect large data sets on hot pollution sites, information that can help inform policies to combat climate change.

“What’s exciting about the OCO-3 result is that this is the first time we get this type of map around a city like LA from space,” says Joshua Laughner, a postdoctoral fellow at Caltech who works all over the world. a monitoring system called Carbon Pillar Observation Network. Although it is useful to see exactly how atmospheric carbon concentrations change over time, tools like TCCON are expensive and require collaborations with trained scientists; therefore, data collection is limited to specific areas. An orbiting observatory, on the other hand, can scan parts of planets that are difficult to study from Earth, such as volcanoes or cities with a large carbon footprint but few control resources.

Launched in 2019, the OCO-3 is mounted on the International Space Station, where it can see almost every city on Earth in an average of three days, according to NASA press release. It is an improvement on the previous one, which was still active, the OCO-2, which can collect a set of data 10 kilometers wide and is locked in an orbital solar synchrony that passes through LA at the same time every day. check only atmospheric CO in the city₂ levels at 1:30 p.m.

“With OCO-3, we have much better spatial coverage, as well as temporary coverage, because we can now look at the city at different times,” says postdoctoral scholar Dien Wu Caltech, who works with the team to study urban emissions. The OCO-3 can perform multiple scans in a single location by mapping an 80-square-mile photograph in just two minutes.

The color of each pixel This map was created by the Eldering team Indicates atmospheric CO₂ concentration in an area about 1.3 kilometers wide on the ground. Because carbon dioxide absorbs some wavelengths of light, scientists can use this information to deduce how much is in the Earth’s atmosphere. OCO-3 saw changes in the intensity of sunlight as it passed through a vertical column of air and generated a reading of how much CO₂ he was in that place.

The OCO-3 team then compared these satellite data to “clean air” using a ground-based TCCON instrument at NASA’s Armstrong Flight Research Center in the desert north of LA, far from local emission sources. About 410 parts per million (or 410 CO.)₂ per million molecules of dry air), OCO-3 was able to identify differences of up to half a million. They saw an overuse of CO₂ more than five parts per million in the LA basin. That may seem small, but it is the same as the number of emissions that are being emitted worldwide in a couple of years.