Free tropospheric aerosol in the North Atlantic was studied at the Pico Mountain Observatory located on the Pico volcano in the Azores, Portugal (2225 m asl; 38.47°N, 28.40°W). Overall the aerosol chemical, morphological and physical properties indicate a predominance of biomass burning emissions during polluted North American outflows. Black carbon (BC) equivalent mass concentrations have been measured at the station since 2001 with a 7-wavelength aethalometer and were analysed to study seasonal and diurnal variations. There was a large day-to-day variability in the BC values due to varied meteorological conditions that resulted in different diurnal patterns for different months. The daily mean BC at this location ranged between 0 and ~430 ngm-3, with the most frequent values occurring in the range 0-100 ngm-3. The BC values exhibited a consistent annual trend being lower in winter months and higher in summer months, barring year to year variations. Recently, additional aerosol properties were studied using a set of four high-volume samplers for the chemical analysis of aerosol, a 3-wavelength nephelometer to measure aerosol light scattering and backscattering fraction, a two channel optical particle counter and a sequential sampler to collect aerosol for electron microscopy analysis. Summertime daily concentrations of free tropospheric organic carbon, elemental carbon, water-soluble organic carbon (WSOC), anions and cations were measured from the high-volume filter samples. Selected WSOC samples from September 2012 were further analysed using ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). In this analysis, an increase in aerosol loading was linked to biomass burning emissions using detailed molecular properties and markers associated with the aerosol despite the long-range transport from North America consistent with previous observations.