Biogenic coastal aerosol production and its influence on aerosol radiative properties

Coastal zones have been shown to provide a massive source of new, tidal-related. aerosol particles in the atmospheric boundary layer with concentrations exceeding 1,000,000 cm^-3 during nucleation bursts sustained over many hours [O Dowd, 2000]. While coastal regions are very strong sources of natural aerosol particles, hithertofore, it has not been demonstrated that these particles contribute to aerosol-related radiative flux. In this brief report, evidence is presented for growth of these new particles, following tidal-related particle formation, into radiatively active particle sizes (i.e. radius>50 nm) where an increase in concentration of more than 300% can be seen. This increase of radiatively active particles concomitantly results in more than a threefold enhancement in both aerosol scattering ability (thereby influencing direct radiative flux) and cloud condensation nuclei (CCN) availability (thereby influencing indirect radiative flux). These results provide direct evidence for coastal biogenic emissions significantly enhancing the radiative flux potential of atmospheric aerosols.