Field measurements of particle covariance (eddy flux) have been made at a nearshore marine location by using an active scattering aerosol spectrometer interfaced with analog signal processing. A classic interpretation of results identifies a predominant particle upflux in the diameter size range 0.2<D<0.5 μm. Chemical characteristics of the aerosol at the site confirm the presence of sea salt in the size range sampled, indicating that recorded upflux events are linked to sea salt particle production at the surface. However, the aerosol at the site is about half (or more) continental in origin. An evaluation of aerosol transformation processes shows that particle growth and decay mediated by the relative humidity gradients present over the sea may have significantly altered the particle covariance results and hampers the quantitative interpretation of the data.