Ambient aerosol particles play an important role in the overall energy balance of the atmosphere by scattering and absorbing incoming and outgoing solar and terrestrial radiation (the “direct effect”) and by modifying microphysical properties of clouds (the “indirect effects”) through their role as cloud condensation nuclei.

The determination of the direct effects of aerosols on the earth radiation balance requires quantitative information on the optical properties of atmospheric aerosols.

Through scattering and absorption of solar radiation, aerosols can cool or warm the Earth’s atmosphere and alter the climate. Measuring the scattering variability is a try to understand how the aerosol optical properties vary with time, season and long range transport of pollutants.

Moreover, information on the extinction coefficient, which is related to visibility in the atmosphere, is also an important parameter in global climate models.

In general, the interaction of a scattering and absorbing aerosol with the radiative flux at various levels in the atmosphere could change the albedo of the earth and the temperature profile of the atmosphere: pure scattering will increase the albedo of the earth and reduce the amount of solar radiation incident on the earth, causing a net cooling of the earth-atmosphere system, while absorption of solar and terrestrial radiation by particles could cause a greenhouse effect near the earth's surface. Uncertainty on the aerosol effect on global radiative forcing is still very high, as also reported by the Intergovernmental Panel on Climate Change.

The objective of this measurement program is to determine the variability of aerosol scattering coefficient at ICO-OV in relation to air mass origins, and to derive information to describe the most common conditions observed at ICO-OV. In addition, observed values of the scattering coefficient, combined with absorption, can be used to estimate the direct aerosol radiative forcing for the region.

The station is equipped to perform continuous measurements of optical

(absorption and scattering coefficients) properties of aerosol.