NUMBER CONCENTRATION, SIZE DISTRIBUTION AND FINE PARTICLE FRACTION OF TROPOSPHERIC AND STRATOSPHERIC AEROSOLS
Li Xu1,*, Guangyu Shi2, Li Zhang1, Jun Zhou3 and Yasunobu Iwasaka4 1National Climate Center, China Meteorological Administration, Beijing 100081, P. R. China 2Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, P. R. China 3Anhui Institute of Optical and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, P. R. China 4Solar and Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601, Japan *Author to whom correspondence should be addressed. Tel: 0086-10-68408578, E-mail: firstname.lastname@example.org
Aerosol observations were carried out at Xianghe Scientific Balloon Base (39.45N, 117E) using a strato-spheric balloon. The particle number concentrations of the tropospheric and stratospheric aerosols were directly explored. The vertical distributions of the number concentration, number-size (that is, particle number versus particle size) distribution, and the fraction of fine particles (0.5 mmr0.15 mm/ r0.15 mm) are reported in this paper. The profiles of particle concentration present multi-peak phenomenon. The pattern of size distribution for atmospheric aerosol indicates a tri-modal (r=~0.2 mm, ~0.88 mm and ~7.0 mm) and a bi-modal (r=~0.13 mm and 2.0 mm). The number-size distribution almost fits the Junge distribution for particles with r0.5 mm in the stratosphere of 1993 and the troposphere of 1994. But the distributions of coarse particles (r0.5 mm) are not uniform. The number-size distribution exhibits also a wide size range in the troposphere of 1993. The results demonstrate that fine particles represent the major portion in the tropo-sphere during the measurement period, reaching as high as 95% in 1994. Certain coarse particle peaks in the tropo-sphere were attributed to clouds and other causes, and in the stratosphere to volcanic eruption. The stratospheric aerosol layer consists of unique fractions of fine or coarse particles depending on their sources. In summary, the process of gas-to-particles conversion was active and the coarse particles were rich over the Xianghe area. The measurements also demonstrate that the spatial and temporal atmospheric aerosol distributions are nonuniform and changeful.