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Dryden assists in African environmental studies
Aerospace Projects Writer and Ames Public Affairs NASA and international scientists are studying African smog and its role in global change and tracking the movement of air pollution in the southern part of the 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. NASA researchers are among more than 100 scientists who are now conducting 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, and ending this month. Flights and science activities are based in Pietersburg, Republic of South Africa. Dryden Mission Manager Walter Klein recently returned from South Africa and explained some of Dryden's role. "Most of the controlled burns or fires are intentionally lit by SAFARI 2000 scientists in the field, while a Dryden pilot is flying above measuring the effects of the burning in coordination with overflights of NASA's Terra satellite. The results are immediate and downloaded from our eight instruments on board ER-2 No. 809," Klein said. "The pollution is significant. The sub-Saharan countries have little or no control on burnings and at times they are literally burning 1 million acres daily. This time of year they are at the end of the dry season and heading into summer. The fires put numerous particles and harmful gases in the air. The weather patterns during spring are associated with high-pressure systems and not much wind, allowing the smoke and pollution to react with clouds and circulate over the continent in a huge cyclonic direction. The smoke does not readily blow off the southern African continent," he said. The uncontrolled burns are set by farmers and ranchers, mostly conducted to clear African savannas to better grow grass to feed cattle. Burning the tall grasses has been a way of life for centuries here, he said. "This was NASA's first involvement with African countries on this scale. We helped build the effort with the scientific communities to study the phenomenon caused by the fires," he said. Dryden's Airborne Science ER-2 high-altitude aircraft is making regular research flights from Pietersburg. The aircraft is carrying instruments that will, in part, validate instruments on NASA's Terra satellite. The ER-2 carries simulators for three of Terra's five instruments. The first simulator, Measurements of Pollution in the Troposphere Airborne Simulator (MOPITT-A), measures carbon monoxide and methane in the atmosphere. A second, the Airborne Multi-angle Imaging Spectro-Radiometer (AirMISR), can distinguish different types of clouds, aerosol particles and surfaces. The third is the Moderate-resolution Imaging Spectroradiometer (MODIS) Airborne Simulator. The simulator's spectral bands are sensitive to fires and can provide estimates of the amounts of aerosols and gases released into the atmosphere through measurements of reflected light and energy. The ER-2 is also flying a solar flux radiometer instrument. Scientists will use data from this instrument to find out how much solar energy is absorbed by particles of smoke, dust and other aerosols and how much energy clouds reflect. Additional instruments on the ER-2 are the Cloud LIDAR (Light Detection and Ranging) device which provides data on the true height of cloud boundaries and clouds' density structure; Scanning High Resolution Interferometer Sounder which forms a photographic record of light interference patterns from upwelling atmospheric and surface radiation; and the Leonardo Airborne Simulator, an airborne micro-satellite sensor which scans the atmosphere and ground in the hyperspectral range for fires, aerosols and vegetation. The ER-2 is capable of carrying a payload of instruments in a nose bay, the main equipment bay behind the cockpit, two wing-mounted superpods, and small underbody and trailing edge pods. The aircraft typically flies at 65,000 feet. Most missions last about six hours with ranges of about 2,200 nautical miles. The SAFARI effort includes 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 as well as 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 are collaborating to conduct the science initiative. NASA's Earth Observing System project is the primary sponsor of U.S. participation in SAFARI 2000. |
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Responsible NASA Official: John Childress For questions, contact: Dryden Web Group Page Curator:WD-Team Modified: September 26, 2000 |
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