Ultraviolet aureole around a source at a finite distance

We calculate the direct and scattered spectral irradiance expected at a detector from an uv source at a finite range and different altitude in a realistic stmosphere. We first present numerical calculations which allow accurately for attenuation by tropospheric ozone for single scattering by air molecules and aerosols and approximately for multiple scattering by air molecules. Such an approximation is reasonably accurate for short ranges and low aerosol concentrations. To include arbitrarily high orders of multiple scattering by both air molecules and aerosols, we assume a uniform atmosphere and use Monte Carlo techniques. Our method is quite general and should work for multiple scattering in any medium at various wavelengths and with arbitrary absorption and scattering functions. Our results should be of interest for remote sensing of the tropospheric ozone layer, measurement of aerosol concentrations, and other trace atmospheric species.