|
 |
|
|
|
A Health Check for the Atmosphere—
|
|||||||
How do factories and offices, homes, and vehicles affect the air we breathe and the climate that shapes our lives? Scientists and technicians from NCAR and elsewhere travel to both pristine and urban areas around the globe to analyze pollutants, including trace gases (those that exist in tiny amounts but can have major impacts, such as ozone) as well as aerosols (tiny airborne particles or droplets such as sulfate, dust, or soot). These expeditions study how pollutants mingle with water vapor, affect cloud formation, and alter the balance of radiation, or energy from the Sun, flowing to and from Earth.
Acid rain was one of the first air-chemistry problems studied by NCAR. In the 1970s and 1980s, scientists from NCAR and their colleagues took aircraft above power plants across the U.S. Midwest and forests across the Northeast to see how industrial emissions of sulfate aerosols were related to the acidity of rainfall many miles downwind. As a result of this and other research, new limits were put in place on industrial emissions of sulfates and nitrogen oxides. Some waterways across the Northeast have since become less acidic, but other locations and the wildlife dependent on their health are still threatened.
In recent years, major field programs have studied the air in some of the world's biggest cities. Atmospheric chemists are seeking the factors behind urban pollution and following plumes "downstream" to see how they affect the air of surrounding rural areas. The Texas Air Quality Study (TEXAQS) examined Houston's multiday spells of health-harming ozone, which forms as sunlight acts on a mix of naturally occurring chemicals and pollutants. During the NCAR-led MIRAGE expedition (Megacity Impacts on Regional and Global Environments), scientists analyzed the chemical and physical transformations in the polluted air flowing outward from Mexico City. Besides offering clues about the impact of the world’s fast-growing megacities on regional air quality, such research will also help scientists assess the impact of sulfates and other pollutants on climate. Planning for MIRAGE also led to a major collaborative effort that became known as MILAGRO (Megacity Initiative: Local and Global Research Observations).
On a larger scale, atmospheric researchers study the spread of pollution across remote oceans and the ways in which pollution can affect global climate. During the Indian Ocean Experiment, over 200 scientists tracked and sampled aerosol pollutants over the densely populated Indian subcontinent and the adjacent Indian Ocean. INDOEX found that soot and other aerosols were playing a much bigger role than previously thought in suppressing clouds and rainfall during the region's dry winter. The study also helped lead to recognition of the atmospheric brown cloud, a vast belt of aerosols now believed to shape climate from Indonesia to India to Mexico.
On the other side of the globe, another big team effort called INTEX-NA (the Intercontinental Chemical Transport Experiment–North America), analyzed pollutants in 2004 as they left North America and moved over the Atlantic Ocean. Aircraft, satellites, and ships from North America to Europe contributed to this field campaign. In spring 2007, PACDEX (Pacific Dust Experiment) is slated to diagnose the quality of air entering North America from Asia. The NSF/NCAR Gulfstream-V, a specially equipped research jet, will fly long-range missions to capture data on the mixture of dust and pollution. Real-time data and samples brought back to the lab will be analyzed to understand global effects on climate.
Home |
Organization |
Research |
News |
Education |
Tools |
Libraries |
Search | 
RSS Feeds | Top
UCAR | NCAR | UOP | ©2008, UCAR |
Sponsored by
This document can be found at
Subscribe to NCAR & UCAR RSS feeds at http://www.ucar.edu/news/rss
