What blows through The Sahara is not in the Sahara. The vast African desert often has dust clouds fly to Europe, turning the snow-capped mountains orange. They sailed across the Atlantic, Fertilizing the Amazon Rainforest with phosphorus. Things that are possible even reach the US.
But for all their obscurity, emissions from the dust of the Sahara – and dirt from any other desert region – are not taken into account in climate models. While satellites can track the beams as they move around the atmosphere, scientists don’t have enough data to clearly show how the dust could cool or warm the planet, accelerating or man-made retardation. climate change.
“Our dataset is based on 5,000 soil samples, and that’s not nearly enough,” said Natalie Mahowald, an Earth system scientist at Cornell University. “No one wants to go to the middle of the desert to find out what the soil is.” So Mahowald has been collaborating with NASA on the Earth’s Surface Mineral Dust Sources investigation mission, or EMIT, which will launch to the International Space Station next month. Their instrument will use a powerful technique called spectroscopy, which astronomers have used for decades to determine the composition of Far away objects, but let’s turn it to earth to analyze our land. That will ultimately give scientists a global portrait of where dust is made, where it’s made, and how those dust particles might affect climate. “It makes more sense to feel from a distance,” says Mahowald.
Any molecule of a material absorbs and then emits electromagnetic radiation in its own way. So astronomers can use a spectrometer to analyze the light emitted by a distant, isolated planet. individual elements such as hydrogen or carbon based on their distinct signatures. That planet may be billions of billions of miles away, but the composition of its atmosphere is betrayed by the light shining from it. It’s like being able to fingerprint someone, even if you can never touch them.
The EMIT spectrometer, which will be attached to the underside of the ISS, will image the Earth in regions 50 miles wide, looking for unique signatures of specific minerals. For example, iron oxide will look different to the spectrometer than clay, although to the human eye the surface of one desert region may look similar to another. “We need to measure the fingerprints of minerals in arid regions,” said Robert O. Green, EMIT principal investigator and researcher at NASA’s Jet Propulsion Laboratory. “We will have enough mineral maps within a year to then start providing new initialization information for climate models.”
Plugging that new data into existing models will help climate scientists better understand the role dust plays in our planet’s temperature. Traditionally, researchers represent dust as a simple medium, a yellow cloud. “But if you look at the soil, they can be all different colors: black, red, white – a very reflective color,” said Mahowald, EMIT’s deputy principal investigator. “Anything darker will absorb more radiation and warm us, and anything lighter will reflect radiation and stay cooler.”
