Results are presented from measurements on the variation of sea spray concentrations and relative humidity (RH) in the lower 15 m of the marine atmospheric surface layer. Particle total area concentrations were determined from measurements of near-forward scattering intensities with an optical device. Both time dependent variations and mean values were recorded as a function of height from 0.5 to 15 m. The profiles of particle total area concentrations and relative humidity show trends similar to previously published particle concentration profiles measured with a rotorod impaction sampler. Hence our previously results are confirmed by using a completeley different technique, based on different physical principles. The time dependent measurements show that fluctuations in the particle total are concentrations are correlated with the motions of the waves under the sampler. Spectral analyses reveal a height dependent frequency, which may be due to the wind profile, to the wave-induced turbulence structure, and to changes in the particle size distribution. Simultaneous time-resolved measurements of RH do not reveal a distinct wave influence. This analysis indicates that water vapor is transported by turbulent diffusion on a time scale much faster than 1 s. The time scale for the response of the largest sea spray particles to the surface displacements is estimated to be longer than 5 s. Theoretical implications are indicated. The results have implications for humidity transport and the constant flux assumption in the surface layer and may be applied to study interaction between wind and waves in the open ocean. ¿ American Geophysical Union 1989