WIND-PRODUCED SUBMICRON PARTICLES IN THE MARINE ATMOSPHERE

The mean relationship between wind speed and the concentrations of con densation nuclei (CN) and cloud condensation nuclei (CCN) has been fou nd from shipboard measurements between latitudes 50-54 degrees S in th e central south Indian Ocean through two winter months. It took the fo rm: log C=a+bU, where C is the particle concentration (cm(-3)), U is t he wind velocity in m s(-1), a was 1.25 for CN (radius r> 1.5 nm) and 0.94 or 0.76 for CCN active at 0.6% or 0.1% supersaturation respective ly, while b was 0.037 for each. This value of b is too low for climati c regulation by wind-produced oceanic CCN to be very important and app ears to be more consistent with earlier data than a recently found val ue of 0.1 for the North Atlantic. Electron microscope photographs of p articles collected in very strong winds showed that sea salt could not account for increases in concentrations of particles with radii less than 50 nm although the CN and CCN measurements suggested a continued increase to smaller sizes, Diffusion battery measurements confirmed th e presence of these small particles but their nature and origin is unk nown.