UI Researchers Study Impact Of Asian Dust On Weather, Climate

Wednesday, May 30, 2007

How do manmade pollution and mineral dust from Asian deserts travel across the Pacific? How do these dust and pollution plumes affect clouds, precipitation and, ultimately, our climate?

Those are some of the questions that an international team of researchers, including a University of Iowa engineering professor, hope to illuminate following their recent completion of a study called the Pacific Dust Experiment, or PACDEX.

Gregory R. Carmichael, professor of chemical and biochemical engineering and associate dean for graduate programs and research in the University of Iowa College of Engineering, says that PACDEX will greatly expand scientists' knowledge of the impact of Asian dust and pollution on the resulting phenomenon called "global dimming," as well as cloud formation, weather and climate change. He, his doctoral students Bhupesh Adhikary, Marcelo Mena, Sarika Kulkarni and Chao Wei and UI Center for Global and Regional Environmental Research (CGRER) researchers Dr. Courtney Hatch and Jeremie Moen were involved in the two-month-long experiment. They provided air pollution forecasts in support of airborne measurement planning and general understanding of the ongoing physical phenomena.

To study changes in the plumes as they move through the atmosphere from Japan to the western United States, the PACDEX team used the NSF/NCAR Gulfstream-V aircraft. The newly configured jet has a range of about 6,000 miles and can cruise at altitudes from a few hundred feet above the ocean's surface to over 50,000 feet, enabling scientists to study the plumes across thousands of miles and at many different altitudes. The Gulfstream-V carries an array of instruments that enable scientists to collect data on clouds, as well as bring dust, pollutants, and cloud particles into the aircraft for study.

Led by scientists at the National Center for Atmospheric Research (NCAR) and Scripps Institution of Oceanography, the study is being funded largely by NCAR's main sponsor, the National Science Foundation. In addition to the UI, NCAR and Scripps, the international research team includes scientists from NASA; the National Oceanic and Atmospheric Administration; the Naval Research Laboratory; the universities of Alaska and Colorado; Arizona State, Colorado State and Oregon State universities; and the National Autonomous University of Mexico. Asian participants include the Japanese National Institute for Environmental Studies, Lanzhou University and Peking University in China, and Seoul National University in South Korea.

Carmichael, who also co-directs the UI Center for Global and Regional Environmental Research, has extensive experience as a researcher of Asian pollution. His three-dimensional atmospheric chemistry model is currently used to track man-made chemicals released into the atmosphere. The UIowa-STEM model, as it is famously known, was one of the principal scientific tools used in PACDEX to design aircraft flight paths to and from the United States. The model provided the airborne scientists with forecasts indicating the time, altitude and direction the plane should fly in order to have the best chance of encountering pollution and dust clouds that would allow them to meet their scientific and measurement objectives.

In October 2005, Carmichael was part of the U.S. delegation attending an environmental conference, "Strategic Approaches to Regional Air Quality Management," in Beijing. In 2004, he received $770,000 in NASA and NOAA grants for air pollution studies in addition to a 2002 five-year, $2.3 million grant from the NSF to use information technology to develop pollution "weather forecasts." He and his UI College of Engineering colleagues were honored with the NASA Group Achievement Award for their contribution to one of the most comprehensive environmental studies of its kind -- the 2004 Intercontinental Chemical Transport Experiment -- North America (INTEX-NA).

Recently, Carmichael, together with CGRER post-doctoral researcher Youhua Tang and members of Scripps Institution of Oceanography, collaborated on a study of "Trans-Pacific transport of black carbon and fine aerosols into North America." Their findings, published in the March 14 online journal of the American Geophysical Union, showed that most of the atmosphere-warming soot transported at high altitudes over the West Coast in the spring comes from Asia.