Climate science boost with tropical aerosols profile

Jul 25, 2013
Fine particles generated by burning of the tropical savanna of Northern Australia are a globally significant aerosol source, with impacts on regional climate and air quality. Credit: Susan Campbell, CSIRO

Australia's biomass burning emissions comprise about eight per cent of the global total, ranking third by continent behind Africa (48 per cent) and South America (27 per cent).

Lead researcher, CSIRO's Dr Ross Mitchell, said fine particles generated by burning of the tropical savanna of Northern Australia are a globally significant aerosol source, with impacts on and air quality.

"Aerosols play a very important role in modulating climate, yet the knowledge of perhaps the most basic piece of information - the seasonal climatology - remains undetermined for many aerosol producing regions.

"Our latest research defines the aerosol climatology of the Australian savanna - by combining observations from CSIRO and the Bureau of Meteorology monitoring stations across northern Australia, spanning 12-14 years.

"This foundation stone of the aerosol cycle allows hard-nosed testing and development of the aerosol modules used within ," Dr Mitchell said.

Burning is widespread during the May to October dry season, with approximately 30 per cent by area of the savanna regions lying within Western Australia and the Northern Territory being burnt each season. Similar seasonal burning also takes place in the savanna regions of Queensland. The majority of burning is carried out deliberately in order to reduce woody undergrowth and promote subsequent grass growth for grazing, although fires also occur naturally through lightning strikes.

The new monthly climatology shows the expected rise in emissions during the late dry season - when most burning takes place – to a peak in October, with clear evidence of dominant fine-particle smoke emission.

The measurements were carried out at three widely-separated stations across northern Australia.

"It was expected that there would be a lot of variation between the stations due to differences in the timing and intensity of fires, combined with separations of up to 800 kilometres.

"You expect to see a relationship between the measurements if you average them over time, say a month, as the day to day variations are smoothed out and the 'seasonal' factors of fuel flammability and meteorology take over. The measurements indeed confirm this.

"Surprisingly, the relationship remains high even for periods as short as five days. This tells us something unexpected about the combustion and transport of the smoke that needs to be captured by fire models. It also tells us that having just one seasonal cycle for the entire Australian savanna might be enough – simplifying the task of properly representing this aerosol in climate models," Dr Mitchell said.

This research connects with the carbon cycle work of Dr Vanessa Haverd and her team, who recently showed that lack of adequate fire modelling in the Australian savanna contributes very large uncertainty to the regional and national carbon budget.

Dr Mitchell anticipates that the results of the paper will be used to guide development of a fire model for this region.

The paper was published in the 3 July print edition of Geophysical Research Letters.

Explore further: Cats threaten native mammal survival in our tropical savannas

add to favorites email to friend print save as pdf

Related Stories

NASA image: Fires in Western Australia

Apr 30, 2013

In Western Australia, the wet season occurs between December and March and the dry season between May and October. The reversals of prevailing winds in the two season drives the shift from wet to dry and ...

Rapid upper ocean warming linked to declining aerosols

Jul 23, 2013

They partly attribute the observed warming, and preceding cooling trends to ocean circulation changes induced by global greenhouse gas emissions and aerosols predominantly generated in the Northern Hemisphere from human activity.

Recommended for you

Atmospheric boundary layer exacerbated mega heat waves

24 minutes ago

The extreme nature of the heat waves of 2003 in Western Europe and of 2010 in Russia and Eastern Europe even surprised scientists at the time. NWO Veni researcher Ryan Teuling from Wageningen University says ...

Magnitude-7.2 earthquake shakes Mexican capital

Apr 18, 2014

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.

User comments : 0

More news stories

Meth mouth menace

Something was up in Idaho. While visiting a friend in Athol, a small town north of Coeur d'Alene, Jennifer Towers, director of research affairs at the Tufts University School of Dental Medicine, noticed ...