Home – Home – Jornals – Atmospheric and Oceanic Optics 2015 number 12

The absence of explicit information on the “in situ” vertical distribution of optical characteristics of atmospheric aerosol is a common situation because of the complexity and high cost of environmental monitoring from aircraft. The paper presents estimates of effects of stratification of the atmospheric optical characteristics on the downward scattered radiation measured by a sun photometer at the surface of the Earth in two basic configurations - in the solar almucantar and the solar principal plane. The assessments were made on the basis of numerical experiments using the parameters which describe both background (areas with low anthropogenic loading) and extreme atmospheric situations (urban smog, dusty haze over the land, dust cloud above the water surface). It is shown that in the visible region of the spectrum beyond radiation absorption by the oxygen, ozone, water vapor, and nitrogen dioxide the stratification of the atmospheric optical characteristics has no significant effect on the sky radiance in solar almucantar, but in the solar principal plane it plays a significant role. The vertical variation of the aerosol extinction coefficient is the main factor. Using the simplified vertical profiles, in particular, the exponential distribution of the extinction coefficient, the error in the radiance calculation can be significantly reduced.