Volume 8, Number 5     September/October 2000

NASA Scientists on “SAFARI”

African smog and its role in global change are under study by NASA and international scientists who are now tracking the movement of air pollution in the southern part of the African continent.

The southern African atmosphere is particularly vulnerable to air pollution due to a persistent high-pressure system there. African smog is a “soup” of smokes from industry, mining, agricultural burning and other sources.

According to Philip Russell, who works at the Atmospheric Chemistry and Dynamics Branch, part of NASA Ames Research Center at Moffett Field, California, satellite measurements of airborne particles, including smoke and haze, as well as water vapor and ozone, were taken. Plans call for the results to be used for improving the measurement accuracy. “We want to better understand the effects that smoke, haze and trace gases have on the African and global climate. We also want to help improve remote measurements of the Earth’s surface, for example, measurements of vegetation and ocean color,” said Russell.

NASA researchers were among more than 100 scientists who conducted extensive and varied field studies as part of the Southern African Regional Science Initiative (SAFARI 2000) that has been underway for more than a year. Flights and science activities were based in Pietersburg, Republic of South Africa.

Russell's team measured and analyzed sunlight with an airborne sunphotometer carried on the University of Washington CV-580 aircraft. The sunphotometer measures the amount of sunlight that penetrates smoke and other aerosols in the atmosphere at different wavelengths, including ultraviolet, visible and infrared light.

Russell’s researchers matched airplane flights with satellite overpasses, and sampled smokes from burning vegetation as well as industrial emissions. Other investigators on the CV-580 aircraft and on the ground simultaneously measured a variety of aerosol properties during data consistency tests.

In addition to Russell, Ames scientists on his team included Beat Schmid and Jens Redemann. A second Ames team, led by Peter Pilewskie, conducted other African field studies. His “radiation group” flew a solar spectral flux radiometer instrument on a NASA ER-2 airplane and on the University of Washington’s CV-580 aircraft. Scientists used data from the instrument to find out how much solar energy is absorbed by particles of smoke and dust and other aerosols, and how much energy clouds reflect. In addition, the researchers tested the ability of satellites to make the same measurements from space.

	Participants prepare a radiometer array in support of SAFARI 2000 studies of solar radiation and climate. (NASA photo.)

The NASA Ames studies were part of the larger SAFARI effort. It included analysis of terrestrial ecology and land processes, land cover and land use change, atmospheric aerosols and trace gases, clouds and radiation, hydrology and computer modeling. Researchers are studying these elements by using ground and airborne measurements complemented by remote sensing observations from older satellites, in addition to a new generation of Earth observation satellites. They include sensors on NASA’s Terra, Landsat 7 and SEAWIFS satellites as well as the European ENVISAT and POLDER II spacecraft.

The study region for SAFARI 2000 includes Botswana, Lesotho, Malawi, Mozambique, Namibia, South Africa, Swaziland, Zambia and Zimbabwe. Scientists from the United States, Canada, the United Kingdom and Germany collaborated to conduct the science initiative. NASA’s Earth Observing System project was the primary sponsor of U.S. participation in SAFARI 2000.

More SAFARI 2000 information, including listings of additional experiments and organizations, is on the Internet at: http://safari.gecp.virginia.edu and http://eos.nasa.gov

.

Credits