Newswise — Moisture-laden clouds frequently gather over the heavy industrial regions of southeastern China, yet little rainfall is recorded there. A University of Maryland scientist, working with climate experts from NASA, the U.S. Department of Energy (DoE) and the Chinese Academy of Sciences, discovered one reason may be in a component of those clouds: aerosols.
A heavy concentration of aerosols -- tiny airborne particles of soot, dust, sulfuric acid and organic matter -- can affect rainfall, air quality and the amount of solar radiation reaching the Earth's surface, according to the researchers. Their initial findings from a seven-month study are featured in an article published this week (Sept. 24) in Nature magazine.
"To better understand the impact of aerosols in China is to better understand climate change worldwide," says Zhanqing Li, a professor of atmospheric and oceanic science (CMPS) at Maryland and lead investigator of the project.
Li, who has conducted aerosol research in his native China for more than a decade, says this latest effort represents the largest-ever field experiment on climate research between the United States and China.
Previous studies have shown that different types of aerosols can exhibit quite different effects on climate, says Hongbin Chen, a professor in the Institute of Atmospheric Physics, Chinese Academy of Sciences. "We wanted to gather a large amount of [new] data to improve on the numerical models already in place regarding aerosol-cloud-radiation interaction," he says.
China Monitoring Site. Click to see a larger graphic.The study, which began in May 2008, started with placing remote-sensing instruments in four locations in China (see illustration - left). The state-of-the-art instruments were deployed under the umbrella of the DoE's Atmospheric Radiation Measurements (ARM) program.
The researchers used lidar -- which sends pulsed laser signals skyward -- to measure the concentrations of aerosols and how far these often-industrial byproducts might drift in the atmosphere. Radar was used to determine the height and density of clouds in the region, while other sophisticated equipment measured solar and infrared radiation levels.
"The four locations gave us a good sampling of aerosol impact, including from human activity and from natural matter [dust] from the desert regions," says Warren Wiscombe, a NASA researcher who is chief scientist for the ARM program.
By coordinating these ground measurements with tracking data from NASA satellites, scientists also determined that aerosols could affect weather and climate across East Asia. Li says aerosols born in China can travel over the Pacific to the U.S. and are even suspected of having an impact on the Asian monsoon system.
Li and the ARM researchers used solar radiation measuring equipment to study the impact of aerosols in China.
The Nature article also details challenges the multinational group of scientists faced with Chinese government oversight. Part of the research occurred during the 2008 Summer Olympics in Beijing, and the arrival of much of the scientific equipment was delayed by months, until it cleared Chinese customs.
But the Olympics added an interesting element to the project, says Wiscombe. "We were able to sample aerosols downwind of Beijing both before and during the event, when much of the industrial activity was curtailed in order to decrease air pollution," he says.
Ultimately, Li says, aerosol research should give scientists a baseline to establish more exact definitions on the relationship between weather and climate patterns and large-scale industrializing. "China is fast becoming the world's leading manufacturer, so the region is a perfect test bed for understanding how human activity can affect climate," he says.WHO: Zhanqing Li, professor of atmospheric and oceanic science at the University of Maryland with a joint appointment in the university's Earth System Science Interdisciplinary Center (ESSIC).
WHAT: Li's research on the impact of regional aerosols in China is featured in the Sept. 24 issue of Nature magazine.
WHERE: The article is available in print (Vol. 461 pp 466-468), on Nature's website, or via PDF download at http://www.newsdesk.umd.edu/pdf/2009/ChinaAerosols.pdf