Winter-to-summer variations of atmospheric turbidity over Mysore (12 degree N, 76 degree E)

A multiwavelength radiometer (MWR) is being operated since 1988 in Mysore (12 degree N, 76 degree E). Solar radiation is collected through ten spectral channels (in the visible and near infrared) for clear sky conditions. From these measurements and using Langley technique, data base on aerosol optical depth, tau sub(p lambda ), for the period 1988-98 has been established. The number density and size distribution of aerosols are related to aerosol optical depth (or extinction) through the Angstrom's equation tau sub(p lambda )= beta lambda super(- alpha ), where alpha is size related, beta represents the amount of aerosols, and lambda is the wavelength in mu m. The Angstrom parameters alpha and beta are obtained from the mass plots of optical depth versus wavelength on a log-log scale. The values of alpha and beta for the winter (December and January) and summer (March and April) months and their inter-annual variations have been examined to assess the influence of meteorological factors and atmospheric pollutants on atmospheric turbidity