Aerosols originating from volcanic emissions have an impact on the climate: sulfate particles from volcanic emissions reflect solar radiation, act as cloud condensation nuclei, and modify the radiative properties and lifetime of clouds, and therefore influence the precipitation cycle. These volcanic particles can also have an impact on environmental conditions and could be very dangerous for aircraft in flight.

Lidar (light detection and ranging) techniques represent a very powerful instrument to obtain information on the aerosol vertical distribution in the atmosphere and to provide data about the presence, altitude, layering and optical properties of a cloud of volcanic origin.

EARLINET, the European Aerosol Research Lidar NETwork, established in 2000 is the first coordinated lidar network for tropospheric aerosol study on continental scale. The network activity is based on scheduled measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a standardised data exchange format. At present, the network includes 27 advanced lidar stations distributed over Europe.

Coordinated EARLINET lidar observations have been carried out after several volcanic eruptions. These lidar observations have been used for studying long-term trends in the stratospheric aerosol load. EARLINET has also monitored more recent events of volcanic eruptions in the North Pacific region (2008-2010) that emitted sulfuric acid droplets into the upper troposphere - lower stratosphere (UTLS) height region of the northern hemisphere. Moreover, EARLINET was used to study volcanic aerosols in the troposphere from two different volcanoes in Europe Mt. Etna (2001 and 2002 eruptions), and the Eyjafjallajökull volcano in Iceland (April - May 2010 eruption).

These EARLINET observations represent an unique dataset for satellite data validation and integration, and for transport model evaluation.