The aerosol studies during the ARctic EXperiment (AREX) campaigns were carried out onboard the r/v Oceania research ship between 1996 and 2004. During each campaign the r/v Oceania cruised for seven weeks (June-August) in the area of the Arctic between 0 and 14E and 69 and 79N. In 2002 the measurements were also carried out from the station in Ny-Ålesund on Spitsbergen in co-operation with the AWI team. The aerosol studies were conducted using an ensemble of instruments, including the FLS-12 lidar, laser particle counter CSASP-100-HV-SP, sun-photometers and ozonometer (Microtops II). The laser particle counter was placed on a mast of the vessel and moved vertically, which facilitated the determination of the vertical structure of aerosol concentrations and their size distribution at altitudes of up to 20 m a. s. l. Simultaneously lidar FLS-12 provided the vertical profiles of aerosol concentrations at altitudes of up to 500 m a. s. l. Those were further used for the calculation of aerosol optical thickness. During the measurements at the Ny-Ålesund Koldewey-Station of AWI, the Koldewey Aerosol Raman Lidar (KARL) was used to investigate the different aerosol scenarios. KARL is also regularly operated throughout the year, particularly during spring.