For the first time, a space mission will be responsible for accurately determine the composition of the minerals that are present in the haze and that, from the Saharan desert, spreads with the wind over great distances. In this way, it will be possible to better understand the scope of the threat posed by these particles, as well as the effects that this phenomenon has on the climate and ecosystems.
Windblown across continents and oceans, this dust does more than just cloud skies, congest lungs, and leave an unsightly dirty film on windshields. It can also influence the weather, speed up melting, and fertilize plants on land and in the ocean. Particles from North Africa can travel thousands of kilometers around the globe, causing phytoplankton blooms, seeding Amazon rainforests with nutrients and covering many cities in a veil of sand as they absorb and scatter sunlight.
NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) mission, due to launch in Juneaims to deepen researchers’ understanding of these fine soil, silt, and clay particles from Earth’s deserts, and ultimately how they affect climate.
The darker, iron-rich dust absorbs heat from the Sun and warms the surrounding air, while the lighter-colored, clay-rich particles do the opposite. “Different types of dust have different properties (they can be acidic, basic, light-colored, dark…) and determine how the particles interact with the Earth’s atmosphere, as well as with soil, water and organisms” , noted Robert O. Green, principal investigator at EMIT.
It is not known if it cools or warms the weather
Using the EMIT data, he added, “we will be able to map the regions of origin of dust in the world and understand how the planet warms and cools, and how that might change in future climate scenarios.”
Researchers at NASA and other institutions have long focused on the movement of dust through the air, which can take hours or weeks, depending on the size of the particles. Its atmospheric impacts are included in climate models, but it’s not clear if that dust has a net warming or cooling effect on the planetand how this is changing over time.
The uncertainty stems from a lack of data on the composition of the dust, explains Natalie Mahowald, an EMIT deputy principal investigator and an Earth system scientist at Cornell University in Ithaca, New York. The researchers’ knowledge comes from fewer than 5,000 sampling locations that are mostly in agricultural areas, where detailed soil information can be used for agricultural or commercial purposes.
“Normally in climate models we model dust as yellow, the average color of all types of dust, but if you’ve ever been to a desert region, you’ll know that sand isn’t the same color,” Mahowald said. “So this assumption that it’s uniform around the world doesn’t reflect what’s happening in reality.”
Mapping the origins of dust
The EMIT mission should clarify that scenario. Installed aboard the International Space Station, state-of-the-art imaging spectrometer will map the world’s mineral dust sourcescollecting information about the color and composition of the particles as the instrument orbits over dry, sparsely vegetated regions.
EMIT will focus on 10 major powder varieties, including those containing iron oxides, whose dark red tones can cause strong heating of the atmosphere. Knowing which types of dust are prevalent on the surface of each region will provide new information about the composition of the particles lifted and carried by the air. With these insights, climate scientists can refine their understanding of the regional and global climate effects of mineral dust.
“Before, scientists worked with individual spectrometers,” Green said. “Now we are actually going to use 1,280 spectrometers on the surface of the Eartheach of which will collect hundreds of measurements per second,” he added.
EMIT will deliver more than a billion new measurements during its mission. Because each type of dust has a unique light-reflecting signature, researchers will be able to determine the mineral and chemical composition of substances on the surface.
The precision of those observations will make EMIT’s instrument one of the most sophisticated Earth-oriented imaging spectrometers ever installed in space.
Reference article: https://www.nasa.gov/feature/jpl/nasa-s-emit-will-map-tiny-dust-particles-to-study-big-climate-impacts