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.
August
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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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.
The
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.
Scientists
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. 
Tuesday,
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.
Right:
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.
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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