The performance assessment of electro-optical (EO) systems with propagation prediction codes requires accurate atmospheric models. The model that is most frequently used for the prediction of aerosols and their effect on extinction in the marine atmosphere is the U.S. Navy aerosol model (NAM) (Gathman, 1983). The nAm was developed for open ocean applications, where it works well. In coastal areas, however, the performance of the NAM may be reduced (Tanguy et al., 1991; De Leeuw, 1993). Based on an extensive series of measurements on the Irish Atlantic coast, an extension of the NAM for the coastal zone is proposed. As in the NAM, the dependence of the aerosol concentration on meteorological parameters is parameterized using empirical coefficients. The effect of the coastal zone is modeled as a function of fetch. A reasonable agreement is found between the model and the aerosol size distributions as measured on the island Inisheer, west of Galway Bay, Ireland.