Aerosol Physicochemistry at Christmas Island: Links to the Oceanic Sulfur Cycle

摘要

The origin of new particles that can replace those scavenged by precipitationprocesses etc. in the marine boundary layer has been a focus of research for many years. We have demonstrated for the first time that diurnal processes in the marine boundary layer related to both aerosol formation and transformation can be observed in the dynamic response of the aerosol size distribution. We were able to show that new particle production was negligible in this region and that heterogeneous conversion information of sulfate took place on existing aerosol. We also demonstrated that subsidence (as evidence by ozone variability) contributed new nuclei into the boundary layer from aloft and that cloud processing and heterogeneous chemistry 'grew' them to larger sizes. This process was shown to be modulated by diurnal photochemistry. We have also developed a thermal DMA system that demonstrated that sea-salt particles from breaking waves extend down to sizes as small as 10 nm and that these particles can be distinguished from other aerosol (eg. sulfate) based upon their volatility.