Diurnal Variations of NSS and MSA Aerosol at Cape Grim During ACE-1

J Heath, B J Huebert, S Howell, L Zhuang, and J Kreidler (All at: Department of Oceanography, University of Hawaii, Honolulu, HI 96822; 808-956-6896; email: huebert@soest.hawaii.edu)

We measured nonseasalt sulfate (NSS) and methanesulfonate (MSA) on filters exposed for three hours each from a tower at Cape Grim during the ACE-1 experiment. Filters simultaneously exposed for 6 hours were used as a quality control check. We sorted the data to isolate periods of "baseline" air, meaning that it was not influenced by continental emissions and was clean remote marine boundary layer air. This data was then examined to identify diurnal variations from which to derive the formation and removal rates of sulfur containing particles. Simultaneous Moudi impactor samples were used to characterize the distribution of each species over the 0.1 to 10 um aerodynamic diameter size range.

We will discuss formation and removal mechanisms and infer oxidation rates from the observed concentration changes.