HR: 1330h
AN: A12B-0093    [PDF]
TI: Aerosol size distributions observed around the tropopause over the Northwestern Pacific Ocean
AU: * Zaizen, Y
EM: yzaizen@mri-jma.go.jp
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Okada, K
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Sawa, Y
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Ikegami, M
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Makino, Y
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Tanaka, T
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Takahashi, H
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Shibata, K
AF: Meteorological Research Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AB: Number-size distributions of aerosol particles in the radius range of 0.008 - 5 $\mu$m were observed at 8 - 11 km altitudes over the Northwestern Pacific Ocean (Nagoya- Petero Pavlovsk - Anchrage; 35 - 61 $\deg$N latitude) during the PACE (Pacific Atmospheric Chemistry Experiment) -7 campaign in February 2000. The vertical profiles indicated that the number concentrations of fine particles ( r $<$ 0.1 $\mu$m radius) were highest at altitude around the tropopause, whereas the number concentrations of larger particles ( r $>$ 0.1 $\mu$m radius) did not change significantly above and below the tropopause. At 8 km altitude (around tropopause), the ultra-fine mode was sometimes found in the size distributions observed in ozone-rich air. However, the mode was not found in the air with low ozone mixing ratios. At 11 km altitude (the lower stratosphere), the mode radius was generally at 0.05 $mu$m and the shape of size distributions suggested that these aerosols were highly aged. This might be typical size distribution of the aerosols in the Junge layer. However, relatively young aerosol-size distributions with the mode radius at 0.03 $\mu$m were also measured. According to the backward trajectories of air parcels, these aerosols were assumed to be transported from the lower altitudes. These results suggested that new particle formation has occurred at altitudes around tropopause. In a part of the region at 8 km altitude, high concentrations of aerosols were found. Soot particles were collected in the air with high mixing ratios of CO in the region. These results gave evidences that anthropogenic pollution has spread to the tropopause region over the Northwestern Pacific Ocean. Results of analysis using numerical model will be shown.
DE: 0305 Aerosols and particles (0345, 4801)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting