Investigation of the stratospheric aerosol by infrared and lidar techniques

Analysis of downward directed infrared irradiances measured in the tropical stratosphere indicated that reasonable limits on the gaseous composition of the atmosphere could not account for the irradiances observed between 14 and 24 km. Additional emitters were therefore assumed to exist at these altitudes. The altitude dependence of the additional emitter compared reasonably well with aerosol profiles derived from lidar backscatter measurements conducted simultaneously in the same region. Mie theory is applied to model aerosol size distributions; the results of such analysis are compared with data obtained at λ = 0.694 μ and 3 μ ≲ λ ≲ λ 100 μ to provide estimates of the size distributions and mass density of the stratospheric aerosol at altitudes of ≃ 18 km.