HR: 1340h
AN: A33A-0832    [Abstracts]
TI: Scavenging processes of marine aerosols by sea fog over the northern North Pacific
AU: * Narita, Y
EM: narita@ori.u-tokyo.ac.jp
AF: Center for International Cooperation, Ocean Research Institute, The University of Tokyo, 1- 15-1 Minamidai, Nakano-ku, Tokyo, 164-8639, Japan
AU: Iwamoto, Y
EM: yoko-iwamoto@ori.u-tokyo.ac.jp
AF: Center for International Cooperation, Ocean Research Institute, The University of Tokyo, 1- 15-1 Minamidai, Nakano-ku, Tokyo, 164-8639, Japan
AU: Yoshida, K
AF: Center for International Cooperation, Ocean Research Institute, The University of Tokyo, 1- 15-1 Minamidai, Nakano-ku, Tokyo, 164-8639, Japan
AU: Kondo, M
AF: Center for International Cooperation, Ocean Research Institute, The University of Tokyo, 1- 15-1 Minamidai, Nakano-ku, Tokyo, 164-8639, Japan
AU: Uematsu, M
EM: uematsu@ori.u-tokyo.ac.jp
AF: Center for International Cooperation, Ocean Research Institute, The University of Tokyo, 1- 15-1 Minamidai, Nakano-ku, Tokyo, 164-8639, Japan
AB: Sea fog appears frequently over the subarctic North Pacific in summertime. Typical advection fog over this region may affect the distribution of natural and anthropogenic substances from lands as well as marine biogenic substances. To clarify the variation of chemical composition in fog water, size distribution of fog droplets and fog scavenging processes, investigation was conducted over the northern North Pacific, where sea fog appears frequently in summer, during the KH-04-3 cruise of R/V Hakuho-maru in 2004. The sea salt composition is governed 65% of total concentration of inorganic ions and the non-sea-salt (nss-) sulfate occupied 10 % in the 90 sea fog water samples. The average size distribution of liquid water content (LWC) of sea fog showed a bimodal pattern with peaks of 7.0 and 27.5 μm in diameter, while its distribution on land fog commonly showed a monomodal pattern. LWC, number concentrations of fog droplets and concentrations of sea salt composition were high at the edge of the fog area, and decreased toward the center of the fog area. The peak of LWC size distribution was shifted from 17.0 μm at the edge to 36.5 μm in the center area. Based on the relationship of chemical compositions between aerosols and fog droplets, nss-SO₄^2- and NH ₄ ⁺ in sea fog water consisted of 85 % of the coarse mode aerosol and 15 % of the fine mode by ion basis. The fog droplets are expected to deposit with growing of its droplet size with coagulation and adsorbing reactive gases as a function of the distance from the edge of the sea fog area. These results suggest that sea fog over the subarctic North Pacific is an important as a scavenger of natural and anthropogenic substances transported from the Asian continent and its nitrogen flux to the marine environment may stimulate phytoplankton growth.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0335 Ion chemistry of the atmosphere (2419, 2427)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 4548 Ocean fog
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting