| | Transcontinental wildfire emissions monitored from space
8 May 2007
Using
data from the SCIAMACHY instrument aboard ESA’s environmental satellite
Envisat, scientists have determined that the carbon monoxide hovering
over Australia during the wildfire season largely originated from South
American wildfires some 13 000 kilometres away.
Using
SCIAMACHY, Annemieke Gloudemans from SRON Netherlands Institute for
Space Research and her colleagues at Utrecht University, the Vrije
Universiteit Amsterdam and the Netherlands Meteorological Institute
(KNMI) witnessed large quantities of released carbon monoxide (CO)
above the southern continents. They also saw increased concentrations
of carbon monoxide above Central Australia, a desert region that is not
prone to forest fires.
"Initially we assumed that the wildfires in North Australia were
responsible for this. Yet when we took a closer look at the transport
of carbon monoxide, we had to conclude that the majority originated
from fires in South America. Even one-third of the carbon monoxide
enhancements above the fires in North Australia originated from South
America," Gloudemans said.
 | | | Envisat view of CO emissions from South America |
Knowledge about the global distribution of carbon monoxide is important because it affects air quality and climate.
SCIAMACHY is the first satellite instrument that can measure the global
distribution of carbon monoxide with nearly equal sensitivity from the
uppermost layer of the atmosphere down to the Earth surface where the
carbon monoxide sources are located.
"SCIAMACHY allows us to map the sources of carbon monoxide and see
where they are blown to," Gloudemans added. "We did this for all of the
continents in the southern hemisphere – South America, Australia and
Southern Africa – for the years 2003 and 2004 and found surprising
results.
"It has been known for many years now that carbon monoxide from
forest fires can be transported over long distances, but one would
expect that the plume would rapidly become more diffuse the longer it
travels. So, it was very surprising to find that even over Australian
biomass-burning areas still up to 30% of the enhanced carbon monoxide
levels from forest fires originate in South America."
| | Smoke from fires over Australia | |
Forest
fires in South America produced much more carbon monoxide in 2004 than
in 2003, Gloudemans explained. "These levels correlated to the amounts
found over Australia for the same periods, confirming that the carbon
monoxide levels over Australia are severely influenced by South
American forest fires."
Plumes of carbon monoxide signal strong biomass burning. Apart
from the carbon monoxide detected by SCIAMACHY, numerous other
compounds are emitted that have severe consequences for air quality and
climate.
Depending on the aridity, much of Australia is prone to fires between
October and March, and the direct consequences for humans and the
environment are disastrous. The fire season in South America, often
concentrated in Brazil, Argentina, Bolivia and Venezuela, lasts from
July to December roughly and contributes up to 50% of the enhanced
carbon monoxide levels in the atmosphere over Australia.
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