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Research on aerosols to improve the prediction of climate change models

Foto: Chris Lunder

From NILU’s annual report 2014: Aerosols are one of the factors influencing climate change. Thus, NILU scientists wanted to find out more about aerosols, in order to make more precise predictions about climate change.

Sonja Grossberndt, Scientist, NILU

Markus Fiebig
Senior scientist Markus Fiebig, NILU.

Aerosols consist of either fine solid particles or liquid droplets, suspended in air or gas. The higher the particle number within a cloud, the more condensing water vapour is distributed over more particles. This makes the cloud turn whiter and persist longer than usual. This process cools the temperature on the earth’s surface, by reflecting more sunlight before it can reach the ground.

Creating clouds

In order to find out more about this effect, NILU scientists use special instruments to create their own clouds at the Birkenes Observatory. Observing them, the scientists expect to find out more about the particles themselves and the effects they can have on the climate. By counting the number of particles that are able to form cloud droplets, climate models can be tested and improved in order to obtain more accurate climate predictions.

– The highest uncertainty for the prediction of climate is the fact that we don’t have any climate data from before the industrialisation phase, explains senior scientist Markus Fiebig at NILU’s Atmosphere and Climate Department.

– In order to find out to what extent climate change processes have been accelerated by human activities, we have to look at areas that are still relatively clean. One of these regions is Central Antarctica.

The cleanest place on Earth

The air in Antarctica is cleaner than in any other place on earth, due to the lack of pollution from local sources. This is why NILU scientists carry out a variety of tests, to find out more about size distribution and optical properties of aerosols in the air.

These characteristics are important, since they describe the direct effect of the aerosol on climate. The results showed that the natural aerosol here undergoes an annual cycle, which can be a reference process for climate models to better represent natural processes in the atmosphere.

Measuring nanoparticles in the air

While doing their research on aerosols, Fiebig and his colleagues also discovered that gasses from the mid-latitudes and the tropics reach the central Antarctic regions in high altitudes. On their way, sunlight oxidises the gasses, resulting in the formation of new particles. Although these particles are very tiny, with a size between 30 and 100 nanometer (one billionth of a meter), they can still be measured in air samples.

Fiebig and his colleagues used data obtained from the Troll Observatory at Queen Maud Land in the FLEXPART model to find out about the origin of particles observed at Troll Station, but whose origin could not be localised before. Further modifications of the model are now envisaged to allow prognoses of future distribution of emissions.