Scientists Launch Asian Dust Study

WASHINGTON (AP) - Scientists know the effect of aerosols on climate is large, ``but the uncertainties are huge,' researcher Barry Huebert of the University of Hawaii said Tuesday at a briefing on the experiment.

Huebert was heading for Colorado to hop a National Science Foundation C-130 research plane bound for Japan to join in the ACE-Asia Project.

The National Oceanic and Atmospheric Administration's research vessel Ronald H. Brown is already en route with 33 scientists aboard. Ships and planes from Japan, Korea and Australia are also taking part in the effort through mid-May.

In recent years many scientists have grown concerned about the possibility of global warming and much of their focus has been on the increasing amounts of gases, such as carbon dioxide, in the atmosphere. The theory is that these gases can trap heat from the sun, causing the planet to warm.

But aerosols - tiny particles of dust, smoke, minerals and materials - also have a significant impact. Studies have shown some of these can add to the warming and others can cause cooling.

``Aerosols play a very significant role in the world's climate system,' said David Evans, NOAA assistant administrator. ``It's clearly a place where we need to make advances in our understanding.'

Indeed, Huebert said their impact may be as large as that of the so-called greenhouse gases.

But scientists don't know in detail which aerosols cause warming and which cool and how much they affect the atmosphere. That's what they want to learn.

ACE-Asia stands for Aerosol Characterization Experiments-Asia. Other studies have been done in Australia, Europe and, on a smaller scale, on the East Coast of the United States.

Huebert said this large effort is being undertaken because Asia is developing, and it will give researchers a chance to look at the aerosols produced now and compare them with how things change in a few years.

Asia produces large amounts of dust from deserts and poor farming practices, smoke from factories, increasing amounts of chemicals, minerals and other particles.

The timing is important. Dust storms occur in winter over the high deserts sending dense plumes over the big cities of China, Japan, and Korea in spring. By summer, thunderstorms change the circulation, disrupting the large dust plumes and raining out much of the pollution.

The ship- and land-based researchers will be able to measure the sun's radiation arriving at the ground, satellites will measure the Earth's radiation upward and the reflected solar radiation and the airplanes will fly through the middle measuring the amount and types of aerosols, he said.

Anne-Marie Schmoltner of the National Science Foundation said instruments on the C-130 will measure aerosol particle size, the number of particles, their chemistry and how the aerosols affect light.

The particles can travel long distances. For example, Asian dust has been measured in Hawaii and even on the west coast of the United States and particles from Africa's Sahara desert have been known to drift as far as Florida and the Caribbean.

The daily activities of the 130 scientists taking part are being directed by Richard Dirks of the University Corporation for Atmospheric Research. UCAR, based in Colorado, is a consortium of university-based atmospheric researchers.

``The science is essential to understanding how human activities are affecting the global climate. The experiment is also groundbreaking in its collaboration among countries that have not worked together in the past and historically have been cautious about sharing data,' Dirks said in a statement.

Besides NOAA and NSF, the project is supported by the Office of Naval Research, NASA and research organizations in Australia, China, France, Japan, Korea, Taiwan and the United Kingdom.

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