Researcher Studies Effects of Dust on Climate Change

Being able to accurately predict how the climate will change in the future is one of the most important quests of our lifetimes. A key to better prediction is the fundamental understanding of how particles in the atmosphere are connected to climate and climate change. One way to do that is to better understand the interactions between desert dust particles and radiation — from the sun and the Earth's surface.

Life and Environmental Sciences Professor Adeyemi Adebiyi is studying those interactions, thanks in part to a new grant from the Department of Energy (DOE), Office of Science. He is the only one from UC Merced, of the 24 researchers across the country, selected to receive part of the DOE’s $15.3 million for Atmospheric System Research projects. He will receive about $500,000 over the next three years for the project.

“There are particles in the air that only cool the climate, but a select few also warm it. Desert dust is one of the particles that can do both. Dust particles are important to our understanding of the Earth's radiative budget— the overall balance between the incoming energy from the sun and the outgoing thermal (longwave) and reflected (shortwave) energy from the Earth. But it remains unclear exactly whether dust’s overall radiative effect is to warm or cool the global climate system,” Adebiyi said. “My project will investigate how largely overlooked pathways of interaction between desert dust, clouds and radiation will influence our understanding of how the Earth's climate system works.”

Other selected projects cover a range of atmospheric science topics, including process-level scientific understanding of how atmospheric particles invigorate storms; processes that govern rain, snow, and snowpack in the Rocky Mountains; processes affecting low-level clouds; and impacts of atmospheric particles, heat and moisture on clouds in the Southeast.

Adebiyi, who is affiliated with the Sierra Nevada Research Institute, is studying the impacts of terrestrial radiation by desert dust on warm low-altitude clouds, a subject that has not been heavily investigated.

Mineral dust accounts for about two-thirds of the masses of all aerosols and absorbs about a third of the solar radiation in the atmosphere. It is important, he said, to have an accurate representation of all the pathways of dust interactions. They include the direct radiative effect, in which dust directly scatters and absorbs solar and terrestrial radiation, and the dust semi-direct radiative effect, in which the interaction with radiation is further enhanced or inhibited by the presence of clouds.

“Unlike other aerosol particles, which are generally very tiny, dust particles are relatively big, allowing them to interact with the whole spectrum of radiation,” Adebiyi said.

Collaborating with researchers at Argonne and Lawrence Livermore national laboratories, Adebiyi and his Aerosol-Climate Group will work with data from two Atmospheric Radiation Measurement (ARM) sites: the Eastern North Atlantic, on Graciosa Island in the Azores, west of Portugal, and the Southern Great Plains, in situ and remote-sensing instrument clusters arrayed across about 9,000 square miles in north-central Oklahoma and south Kansas. The Southern Great Plains observatory is the world’s largest and most extensive climate research facility.

The Southern Great Plains observatory sits in what is known as the Dust Bowl, and the Eastern North Atlantic data will allow him to look at some of the interactions between radiation and dust from the African continent.

“Africa is one of the understudied continents in the world, and yet it has a huge impact on climate,” Adebiyi said. “Africa is a major source of desert dust into the atmosphere, with the Sahara Desert being the largest source of dust in the world by area and by volume.”

He and his research team will “conduct analyses that partition the ARM observations into cases that characterize impacts of dust absorption properties due to large dust particles, dust-cloud vertical configurations and dust vertical distributions,” Adebiyi wrote in his proposal. He will be accounting for the influence of terrestrial radiation on dust-cloud interactions, which has been mostly unaccounted for in previous studies.