Scientists use latest technology to examine aerosol particles that influence clouds

Washington, July 26 : Scientists are using instruments like an aerosol mass spectrometer to examine the life cycles of atmospheric aerosols that can absorb and scatter light and influence the lifetime of clouds.

Chemists from Aerodyne Research Inc. and Boston College (BC) have designed the instrument.

According to Chemistry Professor Paul Davidovits and Aerodyne Principal Scientist Timothy B. Onasch from BC, the novel spectrometer allows researchers to better understand what happens to the sub-microscopic particles.

"For scientists looking at climate change, the biggest uncertainty has to do with the effect of aerosol particles in the air," said Davidovits. "The issue is made that much more complex because aerosols can have different effects on climate. That means the target is constantly shifting," he added.

The historic role of carbon-laden soot in climate change has been identified by researchers, particularly through ice samples taken from glaciers.

Now, scientists are focusing on tiny airborne particles of black carbon released into the atmosphere today in order to better understand the lifecycle of these aerosols in the atmosphere.

In the race to determine the scope and speed of climate change and the influence of human activities on it, huge scientific efforts have focused on carbon dioxide gasses emitted largely from the burning of fossil fuels.

Scientists believe particulates like black carbon may also contribute significantly to global warming.

For more than 15 years, Davidovits and his Aerodyne colleagues have pioneered the study of soot particles and gas-particle interactions, strengthening an understanding of the role of cloud and aerosol chemistry in acid rain, ozone depletion and climate change.

Aerosols raise temperatures, such as when black particles of soot rise in the sky, absorb sunlight and turn it into heat.

Aerosols also can cool by reflecting light away from the earth. Clouds overstuffed with aerosols can inhibit rainfall.

While soot emitted from sources like diesel engines and electric power plants is a focus of study, not all aerosols are man-made. The deserts and arid landscapes of the world produce an estimated 10 to 20 billion tons of mineral aerosols a year.

The air is full of biological aerosols as well - microbes, cells, and particles containing organic compounds.

Aerosols are somewhat fleeting. Unlike carbon dioxide, which can remain in the atmosphere for years, aerosols have an atmospheric life of about 10 to 20 days. In that time, they can absorb other molecules that alter their original state.

"Measuring the many forms of atmospheric aerosols has led researchers to invent new devices, known as research-grade aerosol particle characterizing instruments," said Davidovits.

"The challenge now is to fine-tune those instruments in concert with each other in order to set reliable scientific benchmarks for future study," he added.

ANI