The results of spectral aerosol optical depth measurements in the Pacific Ocean, Baltic Sea, and North Atlantic are considered with regard to air mass types. It is found that the optical properties of continental and maritime air mass types differ significantly for the data employed in this study. A synoptical air mass context was also employed in demonstrating the correlation between near infrared aerosol optical depth &tgr;a (1640 nm) and wind speed as well as for investigations into the relationship between deck level relative humidity and the aerosol optical depth at 550 nm. Simulations, employing well-known aerosol parameterization models, of the aerosol optical depth spectra for various air mass types show good agreement with the experimental results in the visible and near infrared range. ¿ American Geophysical Union 1995