UMBC Physics Professor Co-Authors Science Paper on How Aerosols Impact Cloud Formation, Climate

Researchers at UMBC, NASA-Goddard Space Flight Center and the Weizmann Institute in Rehovot, Israel studying the connection between the burning of vegetation and cloud cover in the Amazon region have found a clearer picture of how aerosols – the tiny particles that make up dust, soot, smoke and ocean spray – may impact cloud formation and climate change on a global scale. The study was published in the Aug. 15 issue of the journal Science.

Scientists have long known that aerosols play a role in cloud formation, but were puzzled by the fact that aerosols’ impact was inconsistent, causing more cloud cover over the Atlantic Ocean while causing less in South America’s Amazon basin.

Aerosol particles are carried by the wind into the atmosphere, where they become encased by water to form rain droplets that cluster into clouds. Aerosol-rich clouds are more spread out by wind, last longer and produce less rain. Aerosol-rich clouds also trap heat in the atmosphere, making cloud growth and rain less likely.

The research team focused on the Amazon region as a test area, using NASA’s Terra satellite to study cloud and aerosol data. “During the (2005) dry season in the Amazon, the only aerosols of any magnitude are from smoke emerging from human-initiated fires,” said study co-author Lorraine Remer, a physical scientist at NASA’s Goddard Space Flight Center, in a NASA press release.

The end result of the research was an analytical model that should work across the globe.

“As we’d expected in applying our model, increased smoke from the fires created clouds rife with a more pronounced radiative effect -- rich with human-caused aerosols that absorbed sunlight, warmed the local atmosphere, and blocked evaporation. This led to reduced cloud cover over the Amazon,” study co-author Vanderlei Martins, associate professor of physics at UMBC, said in the NASA press release. “And it’s encouraging to know the science behind our model should stand no matter the region.”

The paper, “Smoke Invigoration Versus Inhibition of Clouds over the Amazon,” can be found in the Aug. 15 issue of Science.

A Science podcast featuring the Amazon aerosol research is available at:

http://www.sciencemag.org/cgi/content/full/321/5891/981b

UMBC's long-standing partnership with NASA-Goddard Space Flight Center to monitor global air quality is in the media spotlight today, as the world's attention focuses on the start of the 2008 Summer Olympic Games in Beijing, China and the effects of the city's air pollution on athletes and spectators.

Simon Carn, an assistant research scientist at UMBC's Joint Center for Earth Systems Technology (JCET), was quoted in an Aug. 6 New York Times "Dot Earth" blog post. "Dot Earth" is a blog about the earth, the environment and sustainability by noted science writer Andrew Revkin.

Revkin's post looked at comparisons of sulfur dioxide (SO2) levels in the U.S., Europe and China. SO2, the pollutant that contributes to acid rain, has been banned for years in the U.S. and Europe.

Carn and colleagues in the SO2 Monitoring Group of UMBC JCET/Goddard Space Flight Center studied how satellite images and analysis of the SO2 levels in the air over the three continents showed how China's emphasis on economic growth and lack of expensive, Euro/U.S.-style "smokestack scrubbing" technology for coal-burning power plants and anti-SO2 regulations have left China with backwards-in-time air quality compared to the West.

UMBC/NASA also partner on the "Smog Blog," a daily look at U.S. and global air quality using NASA satellite data. The Smog Blog has also been keeping a close eye on Beijing's air.