J. Acmsol Sci. Vol. 29. Suppl. I, pp. S 185-S 186. 1998 0 1998 Published by Else&r Science Ltd. All tights reserved Printed in Great Britain 0021-8502/98 $19.00 + 0.00 MARINE AEROSOL CONCENTRATIONS AT DIFFERENT LOCATIONS OF THE NORTHERN HEMISPHERE J. PIAZZOLA, A.M.J. VAN EIJK, G. DE LEEUW and M. MOERMAN TN0 Physics and Electronics Laboratory, The Hague, The Netherlands zyxwvutsrqponmlkjihg KEYWORDS Aerosol; Marine; Atmospheric; Air-sea interface The concentrations and fluxes of marine aerosol particles over the oceans are important for, e.g., climatological studies and electro-optical propagation. In this work, a comparison between marine aerosol concentrations at various geographical locations in the northern hemisphere is presented. The data from the North Atlantic (De Leeuw, 1986) are compared with data recorded in different coastal areas, in particular at Inisheer, off the west coast of Ireland (Piazzola and Van Eijk, 1998), at the Outer Hebrides (Smith et al., 1989), in the North Sea during the Maptip experiments (De Leeuw et al., 1994) and in the Mediterranean (Piazzola, 1996). The concentrations of aerosols in the marine atmosphere vary with wind speed. Often, a simple logarithmic relation can be obtained: zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK LogN=aU+b (1) where N is the particle concentration, U the wind speed, a and b are constants. In coastal areas, the variation with wind speed depends on the balance between production of fresh marine aerosols and the removal of continental particles (Van Eijk and De Leeuw, 1992). The dependences on wind speed of the concentrations of particles with a diameter of 5 pm are shown in Fig. 1. The slopes and the intercepts are reported in Table 1. The coastal data concern aerosol concentrations recorded during winds of marine origin, i.e long fetches. The maximum slope for the concentration/wind speed dependence, observed in the North Atlantic, is probably due to the higher waves over the ocean. The aerosol concentration is of the same order of magnitude for three of the four coastal sites. The Mediterranean curve shows a slightly smaller intercept, and a slightly larger slope compared to the Hebrides and Ireland. In contrast, the coastal North Sea zone shows substantially larger concentrations. The differences in the aerosol concentrations and their wind speed dependence are interpreted in terms of effects of the secondary paramaters, such as the initial background aerosol, wave field characteristics, sea temperature, water depth and anthropogenic contributions.