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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D23, 8667, doi:10.1029/2003JD003544, 2003

Seasonal variation of free tropospheric aerosol particles at Mt. Tateyama, central Japan

K. Osada

Graduate School of Environmental Sciences, Nagoya University, Nagoya, Japan


M. Kido

Niikawa Water Museum, Uozu, Japan


H. Iida

Tateyama Caldera SABO Museum, Ashikuraji, Japan


K. Matsunaga

Graduate School of Environmental Sciences, Nagoya University, Nagoya, Japan


Y. Iwasaka

Graduate School of Environmental Sciences, Nagoya University, Nagoya, Japan


M. Nagatani

Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Japan


H. Nakada

Solar-Terrestrial Environment Laboratory, Nagoya University, Toyokawa, Japan


Abstract

Number-size distribution of atmospheric aerosol particles and O3 concentration were measured at Murododaira (36.6N, 137.6E, 2450 m above sea level (asl)) on the western flank of Mt. Tateyama in central Japan from January 1999 to November 2002. This study used nighttime data from 2400 to 0500 hours (local time) on the basis of analysis of their diurnal variation to characterize free tropospheric aerosols and O3 over Japan. The O3 concentration shows small variability (standard deviation of 4 ppbv) with the mean value of 40 ppbv in winter (October to February), large variability (8 ppbv) with the higher mean value of 51 ppbv in spring (March to May), and large variability (14 ppbv) with the lower mean value of 32 ppbv in summer (June to September). Highest monthly mean volume concentration (2.7 μm3/cm3) of accumulation particles (0.3 μm < D < 1.0 μm) was observed in June, while the mean value in winter (October to February) was 0.7 μm3/cm3. On the basis statistics of backward air trajectory analyses, a stagnant airflow in summer over the coastal areas of the Yellow Sea and near Japan is inferred to be a suitable meteorological condition to form enhanced volume concentration of accumulation particles during transport. Associating with the seasonal changes in the dominant air trajectories, SO2 emission from Miyakejima volcano since August 2000 is also an important source of the summer enhancement of accumulation particles. Highest monthly mean volume concentration (11.2 μm3/cm3) of coarse particles (D > 1.0 μm) was found in April, which was about 10 times higher than the mean value of 1.2 μm3/cm3 from summer to winter. Variability of daily nighttime volume concentrations of the coarse particles was high (standard deviation of 13.6 μm3/cm3) in spring and low (about 2 μm3/cm3) in the rest of the year. High volume concentration with large variability of the coarse particles in spring is caused by frequent arrival of Kosa (yellow dust) particles from the Asian continent. Rapid enhancement of coarse volume concentration was often observed to increase as much as 30 times within 3 hours during Kosa phenomena. The year 2001 had particularly strong Kosa activity with a prolonged season starting early January and ending early July.

Received 28 February 2003; accepted 7 July 2003; published 23 August 2003.

Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0320 Atmospheric Composition and Structure: Cloud physics and chemistry; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry.

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Citation: Osada, K., M. Kido, H. Iida, K. Matsunaga, Y. Iwasaka, M. Nagatani, and H. Nakada (2003), Seasonal variation of free tropospheric aerosol particles at Mt. Tateyama, central Japan, J. Geophys. Res., 108(D23), 8667, doi:10.1029/2003JD003544.