Australia under the smoke of South American wildfires

Australia's wildfire season is notorious. Dependent on the aridity, much of the continent is prone to such fires between October and March. The direct consequences for humans and the environment are disastrous, partly due to the toxic carbon monoxide released during the fires. Gloudemans: ‘In the southern hemisphere, incineration of biomass is the biggest source of carbon monoxide in the lower layers of the atmosphere.’

The SCIAMACHY sensors, developed by SRON some ten years ago, are unique because they can detect carbon monoxide throughout the entire atmosphere, from the uppermost layer to the ground. ‘This therefore allows us to map the sources of carbon monoxide and look where they are blown to’, says Gloudemans. ‘We have done that for all of the continents in the southern hemisphere: South America, Australia, and Southern Africa, with surprising results.’

Blown over

With SCIAMACHY, Annemieke Gloudemans and her colleagues at Utrecht University, the Vrije Universiteit Amsterdam and the Netherlands Meteorological Institute (KNMI) saw large quantities of released carbon monoxide above the southern continents. These quantities clearly matched the intensity of wildfires observed by the American satellites EOS-TERRA and EOS-AQUA. ‘Yet we also saw increased concentrations of carbon monoxide above Central Australia, where there is desert’, says Gloudemans. ‘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 the carbon monoxide above the fires in North Australia originated for one-third from South America.’

New Dutch instrument

‘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. That also applies for methane, after carbon dioxide the most important anthropogenic greenhouse gas’, explains Ilse Aben, head of atmospheric research at SRON. ‘SCIAMACHY is currently unique in that area but can only provide a picture of the situation once every month. Moreover 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. 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.’

The instrument, TROPOMI, must gain a place on the earth observation mission TRAQ that is being studied by the European Space Agency (ESA) as a so-called Earth Explorer Mission. TRAQ is devoted to research on air quality and climate change. The most important parties from the Dutch space sector are involved in the preparations for TROPOMI: SRON, Dutch Space, TNO, KNMI and the Netherlands Agency for Aerospace Programmes (NIVR). KNMI will provide the principal investigator for the instrument.

Immersed gratings

Especially for the sensors of TROPOMI, SRON, together with TNO, has developed a smart innovative manner to unravel the short-wave infrared radiation in detail whilst still ensuring the compact size of the instrument. The institutes recently made a joint investment to refine the production process of the 'in silicon immersed gratings’ needed for this. Avri Selig, head Earth-Oriented Science at SRON: ‘The prototype of the TROPOMI infrared module is currently being built with TNO and MECON, under the leadership of SRON. I expect a lot from this development aimed at continuing and strongly improving the measurements of carbon monoxide and methane.’

For the time being Annemieke Gloudemans is delighted with the data from SCIAMACHY. ‘A wealth of information. In the near future, we will gain a lot of new important insights into the emission and spread of carbon monoxide and methane in particular’. Even on holiday, the enthusiastic researcher is busy with her subject. ‘When I took a helicopter trip in New Zealand recently, I saw with my own eyes that smoke particles from the yearly Australian wildfires form annual rings as it were in the permanent snow on the mountain tops.’

The Envisat conference was held from 23 to 27 April in the Swiss town of Montreux to mark the fifth anniversary of Envisat being operational in space.

SRON

SRON Netherlands Institute for Space Research is an expertise institute of the Netherlands Organisation for Scientific Research (NWO). The institute develops and uses innovative instruments for groundbreaking research from space.