Solar glint from oriented crystals in cirrus clouds.

Solar scattering on oriented cirrus crystals near the specular reflection direction is modeled using a mix method combining geometric optics and diffraction effects at three wavelengths in the visible and infrared domains. Different potential sources of phase function broadening around the specular direction, such as multiple scattering, solar disk, or tilt effects, are studied by means of a Monte Carlo method. The radiance detected by an airborne sensor located a few kilometers above the cirrus cloud and pointing in the specular scattering direction is calculated at four solar zenith angles showing a dramatic increase of the signal in relation to the usual assumption of random crystal orientation.

Experimental and theoretical studies of the aureole about a point source that is due to atmospheric scattering in the middle ultraviolet.

In the atmosphere, pointlike sources are surrounded by aureoles because of molecular and aerosol scattering. In various meteorological conditions, this variance field can be a nonnegligible part of the signal detected by a large-field-of-view sensor. A model based on a Monte Carlo technique has been developed to simulate the propagation of radiation coming from a UV point source.

Effects of aerosol scattering phase function formulation on point-spread-function calculations.

The quality of the image produced by an outdoor optical system is affected by the presence of atmospheric aerosols between object and receiver. The properties of the point-spread function that result from aerosol particles were calculated by a new Monte Carlo code called MEDIA (an acronym for Modélisation des Effets de Diffusion Inhérents à l'Atmosphère). The influence of the scattering phase function's angular dependence on the irradiance of the focal plane of a detector was studied.