VARIATIONS OF ATMOSPHERIC AEROSOL CONCENTRATION AND SIZE DISTRIBUTION WITH TIME AND ALTITUDE IN THE BOUNDARY LAYER

The atmospheric aerosol number concentration and size distribution were measured at six levels (50, 100, 150, 200, 250 and 300 m) on the Beijing 325 m meteorological tower by means of an optical particle counter. From the measured value of the concentration Nz and according to the expression Nz = , the value of aerosol scale height Hp was determined by using a least square method. An analysis shows that there are significant variations of aerosol concentration and size distribution in relation to time and altitude. The average size distribution for each level can be described by , where the parameters vary with the altitude.