Lateral variations of aerosols and meteorological properties in offshore winds

Abstract

Aerosol particle size distributions and meteorological parameters were measured during the MAPTIP experiment in the fall of 1993 in the vicinity of MeetPost Noordwijk (MPN), a platform at 9 km from the Dutch coast. One data set was collected at MPN, the other on board of a ship that sailed down and cross wind trajectories. from MPN to a distance of 200 km. Both the aerosol concentration and extinction respond to variations in the meteorological conditions. For down wind trajectories, the responses at ship and platform are observed with a delay in accordance with the time it takes for an air mass to travel from one to the other. For cross wind trajectories, the responses are observed simultaneously at ship and platform. The comparison of ship and platform also shows that the meteorological conditions change as a function of fetch in off-shore winds. This fetch effect does not show up clearly in the aerosol concentrations, which suggests that in off-shore winds the influence of the land (natural, industrial and urban aerosol) extends up to more than 200 km from the coast.