ANALYSIS OF PARTICULATE MASS CONCENTRATION, AEROSOL NUMBER CONCENTRATION AND VISIBILITY IN BEIJING

摘要

Paniculate mass concentration (PM_(10), PM_(2.5)), aerosol number concentration (A_(OPC)), aerosol size distribution and atmospheric visibility were simultaneously measured in Beijing in the summer and winter of 2001. From the profuse data collected, the following conclusions can be drown: (1) there are two peaks for the average diurnal variations of P/W_(10) and N_(OPC) in the summer, an obvious valley can be seen between 12:30 and 15:00 for their average diurnal variation in the winter; (2) there is one single peak for the average diurnal variation of atmospheric visibility in the summer, while there are two peaks in the winter; (3) PM_(10) and N_(OPC) are usually smaller in the summer than those in the winter; (4) the average visibility is much lower during 00:00-09:00 in the summer than that in the winter, because of the very high relative humidity and higher concentration of the large particles (r > 1.25 μm) in the summer during the period; (5) aerosol size distributions usually depend closely on season and relative humidity at the same place.