Abstract

Theoretical and observational works have shown that the simultaneous solar extinction-forward scattering measurement scheme can offer more information about column aerosol size distribution than that obtained from a single extinction measurement owing to the fact that extinction is sensitive to small particles while forward scattering is sensitive to large particles. Based on the above consideration we have carried out a joint lidar-radiometer experiment since early 1982 in the north suburb of Beijing, from which the extinction coefficient profiles and column aerosol size distributions are reversed. The primary results show that:

1) The vertical distributions of extinction coefficient (or aerosol concentration profiles) are strongly influenced by the near ground inversion. From morning till afternoon with the disappearing of inversion the upward transport of aerosol particles results in the decrease of extinction coefficient over 1 Km.

2) The column aerosol size distributions are noticeably changing when the vertical mixing takes place. The number of larger particles tends to increase and that of the smaller particles tends to decrease. The former is an effect of vertical transport and the latter is probably due to the horizontal dispersion by the wind or the decrease of humidity.