HR: 1340h
AN: A53A-0152    [Abstracts]
TI: Marine Particle Nucleation: Observations at Bodega Bay, California
AU: * Wen, J
EM: janwen@ucdavis.edu
AF: University of California, Davis, One Shields Ave, Davis, CA 95616 United States
AU: Zhao, Y
EM: yjzhao@ucdavis.edu
AF: University of California, Davis, One Shields Ave, Davis, CA 95616 United States
AU: Wexler, A S
EM: aswexler@ucdavis.edu
AF: University of California, Davis, One Shields Ave, Davis, CA 95616 United States
AB: Homogeneous nucleation has drawn more attention recently due to the potential for these small particles to grow into cloud condensation nuclei, thus affecting cloud formation as well as the global radiation budget. Nucleation has been observed at different locations around the world; however, the key questions of the chemical composition of the nuclei as well as the exact nucleation pathways remain unresolved. The aim of our study is to identify and characterize nucleation events at Bodega Bay, California. A TSI nano-SMPS was installed in a lab at Bodega Bay, about 50m from the coastline and 5m above sea level. Based on measurements conducted from June to December 2001 and from January to June 2003, we have observed two kinds of nucleation events, i.e. long-term (a few hours) and short-term (a few minutes) particle bursts. The long-term events mostly occur during daytime in the summer lasting from 0.5 hour to 8 hours. Narrow spikes (short-term events) that occur year-round, both day and night, last only a few minutes to a half hour, but contain particle number concentrations comparable to some of the long-term events. Wind direction and speed affect the occurrence and intensity of the particle burst. Nucleation mostly takes place during northwesterly onshore wind for both long- and short-term events. The theoretical estimations of condensational sink for precursor gases and the sea-to-air flux of precursor gas indicate that nucleation is more favourable at higher wind speed, which agrees with our observation at Bodega Bay. The seasonal and inter-annual variations of ultrafine particle number concentration N3-10nm appear to correlate with ocean upwelling, a characteristic of currents along the west coast of US that brings up nutrients from subsurface waters promoting plant productivity and sea-to-air gas transfer. Simultaneous measurements of nucleation at the coast and 1.6 km out suggest that nucleation is a coastal phenomenon supporting the contention that it is related to direct or biogenic emission of precursor gases from the coastal area during the sea upwelling periods.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 4504 Air/sea interactions (0312, 3339)
DE: 4801 Aerosols (0305, 4906)
DE: 4906 Aerosols (0305, 4801)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005