RESUMEN
The solar blind ultraviolet (SBUV) spectral region covers the interval between 230 and 290 nm. The lower limit of this interval is given by the edge of the Schumann-Runge band and the upper limit is determined by solar radiation penetrating the stratospheric ozone shield. The SBUV region is interesting from the experimental point of view, since the lack of solar background is favorable in such applications as lidar, atmospheric communications, and remote sensing. The present models (LOWTRAN-6) include as atmospheric attenuators in this region ozone absorption and aerosol and molecular scattering. New theoretical calculations of the Herzberg I oxygen band predict significant absorption by O(2). This prediction is confirmed experimentally in this study. Field measurements at 252, 255, and 264 nm are reported over optical paths of up to 2750 m. Results show that LOWTRAN-6 is inadequate in the SBUV region, as indicated by the present extinction measurements.
RESUMEN
Several scaling laws have been developed relating hypothetical measurements of the scattering or extinction of the atmospheric aerosols to the scattering or extinction properties of the aerosols at other wavelengths. These scaling laws were tested in a series of numerical simulations using a number of representatives models of the atmospheric aerosols and calculations of their expected scattering and extinction properties. These simulations showed that forward scattering at fixed angles for an ultraviolet wavelength could provide useful predictions of near-IR extinction. A good correlation is also presented between forward scattering for a wavelength of 0.25 microm and backscattering at a wavelength of 1.06 microm. A comparison of 10.6microm extinction with backscattering at 10.6 microm and extinction at a wavelength of 1.06 microm showed too much scatter to develop useful scaling laws in those case.
RESUMEN
The Twomey-Chahine inversion algorithm is applied to experimental atmospheric transmittance data in the 0.4-2.4-microm wavelength range and atmospheric aerosol size distributions deduced. The conditions for successful inversion of transmittance data are investigated in numerical experiments, and it is shown that too small a wavelength range results in a Junge-type distribution in all cases and that noise in the measurements in excess of 4-5% results in inversion artifacts.