South American Carbon Monoxide Blows to Australia

South American Carbon Monoxide Blows to Australia



 
May 2007 -   Much of the carbon monoxide 
hovering over Australia during wildfire season originated from South 
American wildfires some 13,000 kilometers (8,000 miles) away, scientists 
have determined, using satellite data. Knowledge about the global 
distribution of carbon monoxide is important because it affects air 
quality and climate. 
Using data from an instrument aboard the European Space Agency’s 
environmental satellite Envisat, Dutch scientists witnessed large 
quantities of released carbon monoxide above the southern continents. They 
saw increased concentrations of carbon monoxide above Central Australia, a 
desert region that is not prone to forest fires. 

A computer simulation of the trans-continental movement of carbon monoxide 
released from South American wild fires. (Image courtesy SRON)
Plumes of carbon monoxide signal biomass, such as trees or grass, on fire. 
In the southern hemisphere, incineration of biomass is the biggest source 
of carbon monoxide in the lower layers of the atmosphere. 
And apart from carbon monoxide, numerous other compounds are emitted that 
have consequences for air quality and climate. 
"Initially we assumed that the wildfires in North Australia were 
responsible for this," said Annemieke Gloudemans from SRON Netherlands 
Institute for Space Research. "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," Gloudemans said. 
From 30 to 50 percent of the carbon monoxide above the fires in North 
Australia originated from South America, according to Gloudemans and her 
colleagues at Utrecht University, the Vrije Universiteit Amsterdam, and 
the Netherlands Meteorological Institute. 
Depending on the aridity, much of Australia is prone to wildfires 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 and contributes up to 
50 percent of the enhanced carbon monoxide levels in the atmosphere over 
Australia. 
Fire devours a tract of Brazilian rainforest. Some of the carbon monoxide 
emitted blows across the planet to Australia. 
The scientists were able to observe the distribution of carbon monoxide 
using SCIAMACHY, 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's surface where 
the carbon monoxide sources are located. 
The Dutch-German satellite instrument SCanning Imaging Absorption 
SpectroMeter for Atmospheric CHartographY, SCIAMACHY, is an instrument 
whose primary mission objective is to perform global measurements of trace 
gases in the troposphere and in the stratosphere. 
The troposphere is the first layer of atmosphere above the Earth's surface 
and contains half of the planet's atmosphere. Weather occurs in this 
layer. The stratosphere is the next higher level, where many jet aircraft 
fly. 
"SCIAMACHY allows us to map the sources of carbon monoxide and see where 
they are blown to," Gloudemans said. "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 percent of the enhanced carbon monoxide levels from 
forest fires originate in South America." 
Forest fires in South America produced much more carbon monoxide in 2004 
than in 2003, Gloudemans said. "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." 
The SCIAMACHY instrument is carried by the European satellite Envisat, 
launched in 2002. 
"The only way to accurately follow the emission and transport of carbon 
monoxide is to use satellites with sensors that are sensitive enough for 
short-wave infrared radiation," explains Ilse Aben, head of atmospheric 
research at SRON. "That also applies for methane, after carbon dioxide the 
most important anthropogenic greenhouse gas." 
The SCIAMACHY instrument can do the job, but can only provide a picture of 
the situation once a month. In addition, Aben said, Envisat will be 
decommissioned in about 2010. 
"Unless we work quickly on a successor, we will no longer be able to track 
the emission and spread of these substances," said Aben. "Moreover in the 
future, we want to measure carbon monoxide and methane on a daily basis 
and with a greater degree of sensitivity. Consequently at SRON, we are 
busy developing sensors for a new Dutch space instrument that will be able 
to provide a very detailed picture of the composition of the atmosphere." 
Part of the Netherlands Organisation for Scientific Research, SRON is the 
national center of expertise for the development and exploitation of 
satellite instruments for astrophysical and Earth-oriented research. The 
institute acts as the Dutch national agency for space research.  
  

       
      

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