A scanning backscatter lidar was used to measure the depth and structure of the coastal atmospheric boundary layer and the evolution of primary aerosol (sea spray) plumes produced by breaking waves during the New Particle Formation and Fate in the Coastal Environment (PARFORCE) campaign at the Mace Head Atmospheric Research Station (Ireland) in September 1998 and in June 1999. The PBL structure was observed to vary from a single-layer well-mixed structure to multilayered structures. Comparison with in situ aircraft measurements of temperature and humidity exhibited good agreement. Using the lidar in the scanning mode allowed two-dimensional profiling over a spatial scale of 10 km, revealing significant primary aerosol plumes produced by breaking waves, particularly in the surf zone and at high wind speeds on the open sea. The initial plume heights were some tens of meters and evolved to hundreds of meters while transported over only a few kilometers from the source. The plumes were traceable to distances of more than 10 km down wind from the source.