Studying the extinction coefficient due to aerosol particles at different spectral bands in some regions at great Cairo

摘要

Extinction coefficient due to aerosol has been estimated by Pyrheliometric and Gorgie type Actinometric measruements in the industrial, urban areas and compared with agricultural areas. The measurements distributed over one year form June 1992 to May hot wet and spring months and minimum in winter months, but there is a flucturation in urban area. Diurnal variations show maximum at noon especially in the industrial area. Level of extinction coefficient in the industrial and urban area is greater than that of the agricultural area, except for hot wet months is due to the increase of water vapor content in agricultural area. Spectral distribution of the extinction coefficient decreases monotonically with wavelength. Size of particles in industrial area is greater than in urban and agricultural areas. The temperature and water vapor content have important rules in increasing the extinction coefficient of aerosols.