NASA and the Environmental Protection Agency (EPA) completed a short but intense field campaign to study air quality in the San Joaquin Valley in central California in mid-March 2007.

Using instruments on aircraft, satellites, and at ground sites, scientists are working to improve observations and understanding of air quality in this region, an area that is plagued with air pollution. Jim Szykman, an EPA research scientist working at NASA Langley Research Center in Hampton, VA and Rebecca Rosen, also from the EPA, are the co-principal investigators for the San Joaquin Valley Advanced Monitoring Initiative. Together the EPA and NASA are using a suite of instruments to study atmospheric particles, called aerosols, which come from many sources: burning wood; vehicles; construction and agricultural activities; and stationary sources such as refineries.

During the campaign, researchers flew HSRL on NASA 529, a King Air B200 aircraft, based at NASA Langley.

Right now, researchers use aerosol measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS), an instrument on the NASA Terra and Aqua satellites. But, the terrain in the San Joaquin Valley makes it more difficult for MODIS to make accurate measurements of aerosols in this region. Another challenge with MODIS is that researchers cannot see where the particles are located vertically. They can only obtain measurements for the total column of the atmosphere, from the ground all the way to the upper atmosphere. Together, the lidar and MODIS instruments can determine whether this column has a high concentration of pollution and whether that pollution is further up in the sky or at the ground level, where the majority of the population lives and breathes.

Through this field campaign and other efforts during the "Advanced Monitoring Initiative," the EPA is improving its understanding of how environmental factors affect human health and ecological well being. Projects from this initiative will enable a better understanding of how to improve data to support and enhance environmental policy, management, and decision making.

Also, for more information about the San Joaquin Valley campaign, visit:
https://www.nasa.gov/vision/earth/environment/SanJoaquin.html.