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NASA goes on SAFARI

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NASA goes on SAFARI

Scientists using an armada of spacecraft and NASA satellites to study the unique environment of southern Africa.

Terra satellite view of AfricaAugust 16, 2000 -- Anticipation hung in the air Saturday morning as thousands of people -- including world leaders, distinguished scientists and journalists -- gathered on the tarmac of Pietersburg International Airport in the Republic of South Africa. The occasion wasn't the arrival of a head of state or a victorious World Cup football team. It was a ceremony marking the start of an important aerial campaign for SAFARI 2000, an ambitious science project involving a global team of scientists and an armada of airplanes and NASA spacecraft.

SAFARI 2000, which began in August 1999, is a three-year project to study the environment of southern Africa. Targets include smoke and gases released into the atmosphere by industry, biological sources and the burning of African forests and savannas. Using sensors on the ground, on planes, and on NASA satellites, scientists hope to paint a clearer picture of how these emissions affect phenomena ranging from regional crop productivity to global climate change.

Above: An important goal of the SAFARI 2000 project is to verify data from NASA's new Terra satellite by comparing ground- and airplane-based measurements with those transmitted from space. This image is one frame from a 3 MB Quicktime animation showing cloud cover over Africa registered by Terra's MODIS sensor. Terra has many capabilities that will be tested during the SAFARI campaign. [more information about the animation]

"There's a tremendous amount of interest here (in southern Africa) in the media and the general public," said Dr. Michael King, senior project scientist for NASA's Earth Observation System (EOS) program, the primary U.S. sponsor of SAFARI 2000. King was in South Africa for the launch of the campaign.

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"Actually, South African Cabinet Minister Ben Ngubane asked my colleagues, Drs. Robert Scholes and Harold Annegarn, and myself to come brief the South African Parliament when the experiment's preliminary science findings are obtained," King said.

Information gathered during the study is expected to help NASA verify data from several of its satellites and to provide a useful body of knowledge for universities and governments in southern Africa.

The study region for SAFARI 2000 includes Botswana, Lesotho, Malawi, Mozambique, Namibia, South Africa, Swaziland, Zambia, and Zimbabwe.

Southern Africa's natural environment fits the needs of the project for several reasons. For roughly two-thirds of the year, the atmosphere over the region becomes fairly isolated by a high-pressure system that creates a huge "merry-go-round" of air and pollutants over the lower half of the continent. This relatively isolated system is easier for scientists to study than a completely uncontained system.

see captionThe high-pressure area also leads to very little cloud cover during this time of year. Several of the instruments used in the project cannot "see" through clouds. They perform best in clear conditions. The increased sunlight also causes higher levels of photochemical transformation of atmospheric pollutants, which is one of the processes the scientists plan to study.

Left: A map of southern Africa showing 13 test sites for SAFARI 2000. [more information]

Scientific considerations such as these contributed to the choice of southern Africa for a 1992 research project called the Southern African Fire Atmosphere Research Initiative (SAFARI-92).

"SAFARI-92 was a preliminary study with a large impetus from outside Africa to study biomass burning in Africa and its effects on tropospheric ozone levels," said Dr. Chris Justice, a research professor with the Global Environmental Change Program at the University of Virginia, who was involved with spearheading SAFARI 2000.

After SAFARI-92, the scientists involved were left with a lot of unanswered questions and many fruitful collaborative relationships between scientists in the United States and Africa. As the possibility of a follow-up project gained momentum, the idea took on a broad international character.

"During the initial phases when we were conceiving this project, it was in fact a team effort between U.S. academic and NASA scientists and South African academic scientists," said Dr. Harold Annegarn, one of the SAFARI 2000 coordinators for South Africa and leader of the Atmospheric and Energy Research Group at the University of the Witwatersrand, near Johannesburg.

see captionScientists from most of the southern African countries in the study area as well as the United States, the United Kingdom, Canada, Germany, Sweden, France and Belgium are now involved with the project.

Right: SAFARI 2000 scientists collaborating in the field. Photo courtesy of Dr. Chris Justice.

"We had a substantial knowledge base on this side with some very committed scientists," Annegarn said. "So it wasn't just a matter of inviting NASA here to learn, but really a participatory experiment where our regional expertise would greatly aid meeting the American objectives for validation of NASA's Terra satellite, and in turn having NASA scientists in the region would obviously give a very large boost to the local scientific capability."

The current aerial data-gathering campaign -- which is scheduled to last six weeks -- relies on aircraft supplied by NASA, the University of Washington, the South African Weather Bureau and the United Kingdom's Meteorological Office. The first mission flew Tuesday, using a myriad of instruments to survey particulates and trace gases in the atmosphere, such as ozone, carbon monoxide, carbon dioxide, nitrogen oxides and sulfur oxides.

"The aircraft (campaign) provides a profile of the atmosphere, which enables us to characterize the emissions from both wildfires and industry and the (chemical) transformations that are taking place in the atmosphere," explained Justice.

The combination of the ground-based, aircraft-based and satellite-based instruments will allow NASA to verify the data produced by satellites from the EOS program. The newest of the EOS satellites -- Terra -- was launched in December 1999, and verifying its data is a high priority for the space agency.

see captionTuesday, for example, NASA's ER-2 aircraft flew over one of the project's two instrument towers -- located in Kruger National Park, South Africa -- at the same time that Terra passed 705 kilometers (438 miles) overhead. The airplane carried instruments that simulate some of Terra's sensors, including MODIS, MOPITT and MISR. Comparing the data from the airplane and the satellite should allow NASA to confirm the satellite's results.

The many types of data produced by this three-tiered approach (ground, air and space) will help scientists as they piece together the results and try to tackle cutting-edge problems identified at the outset of the project.

Above: A collage showing the NASA ER-2 aircraft, some landscapes in southern Africa and a typical SAFARI 2000 instrument tower. Photo courtesy of Dr. Peter Frost, a research associate with the Institute of Environmental Studies at the University of Zimbabwe. [more information]

For example, one of the questions posed in the SAFARI 2000 science plan reads: "How might changes in atmospheric aerosols and trace gas concentrations affect the regional climate, biogeochemistry and land use of southern Africa?"

Finding the answer calls for research that cuts across many disciplines.

"[We're] trying to address [such] questions in a holistic way, rather than studying isolated parts which fall under traditional disciplines," Justice said. "SAFARI 2000 was integrative in its design. We're looking at land surface processes, fires and other emission sources, atmospheric chemistry, and meteorology, and their complex feedbacks."

The variety of data should also be useful to regional scientists studying global climate change and natural resource management, and also to the governments of the countries of southern Africa as they make policies to manage natural resources.

African factories spew smoke into the airRight: Factories in southern Africa discharge smoky pollutants into the atmosphere. SAFARI 2000 will aid African scientists and political leaders as they evaluate the impact of such industrial activity on the continent's environment.

To ensure that the project data are available to all people of southern African countries, a data repository will be created at the University of the Witwatersrand. NASA will be providing the data collected during the project by its instruments free of charge, Annegarn said. This data center will be for all scientists in southern Africa, providing them with new tools and training to study our environment.

"NASA's explicit wish to make Earth science information available as an international asset still requires commitment and willingness on the part of other countries to exploit that opportunity, and we've embraced that whole-heartedly," Annegarn said.

On February 24, 2000, Terra began collecting what will ultimately become a new, 15-year global data set on which to base scientific investigations about our complex home planet. There are three other Earth Observing System (EOS) satellites currently in orbit and fifteen more will follow over the next four years. Together, these spacecraft will help scientists unravel the mysteries of climate and environmental change. To learn more about these missions, visit the EOS Missions Page.

Web Links

SAFARI 2000 -- The SAFARI 2000 home page.

University of the Witwatersrand -- The University of the Witwatersrand home page.

Terra -- NASA's flagship Earth Observing System satellite.


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